ব্যবহারকারী:প্রলয়স্রোত/অনুবাদের কুঁড়েঘর

সমকামিতা ও মনোবিজ্ঞান

Historical background

The view of homosexuality as a psychological disorder has been seen in literature since research on homosexuality first began; however, psychology as a discipline has evolved over the years in its position on homosexuality. Current attitudes have their roots in religious, legal and cultural underpinnings. In the early Middle Ages the Christian Church ignored homosexuality in secular society; however, by the end of the 12th century hostility towards homosexuality began to emerge and spread through Europe’s secular and religious institutions. There were official expressions condemning the "unnatural" nature of homosexual behavior in the works of Thomas Aquinas and others. Until the 19th century, homosexual activity was referred to as "unnatural, crimes against nature", sodomy or buggery and was punishable by law, sometimes by death. As people became more interested in discovering the causes of homosexuality, medicine and psychiatry began competing with the law and religion for jurisdiction. In the beginning of the 19th century, people began studying homosexuality scientifically. At this time, most theories regarded homosexuality as a disease, which had a great influence on how it was viewed culturally. There was a paradigm shift in the mid 20th century in psychiatric science in regards to theories of homosexuality. Psychiatrists began to believe homosexuality could be cured through therapy and freedom of self, and other theories about the genetic and hormonal origin of homosexuality were becoming accepted. There were variations of how homosexuality was viewed as pathological. Some early psychiatrists such as Sigmund Freud and Havelock Ellis adopted more tolerant stances on homosexuality. Freud and Ellis believed that homosexuality was not normal, but was "unavoidable" for some people. Alfred Kinsey's research and publications about homosexuality began the social and cultural shift away from viewing homosexuality as an abnormal condition. These shifting viewpoints in the psychological studies of homosexuality are evident in its placement in the first version of the Diagnostic Statistical Manual (DSM) in 1952, and subsequent change in 1973, in which the diagnosis of ego-dystonic homosexuality replaced the DSM-II category of "sexual orientation disturbance." However, it was not until 1987 in DSM-III-R that it was entirely dropped as a mental disorder.

Freud and psychoanalysis

Sigmund Freud's views on homosexuality were complex. In his attempts to understand the causes and development of homosexuality, he first explained bisexuality as an "original libido endowment," by which he meant that all humans are born bisexual. He believed that the libido has a homosexual portion and a heterosexual portion, and through the course of development one wins out over the other. He also believed in a basic biological explanation for natural bisexuality in which humans are all biologically capable of being aroused by either sex. Because of this he described homosexuality as one of many sexual options available to people. Freud proposed that humans' inherent bisexuality leads individuals to eventually choose which expression of sexuality is more gratifying, but because of cultural taboos homosexuality is repressed in many people. According to Freud, if there were no taboos people would choose whichever was more gratifying to them- and this could remain fluid throughout life- sometimes a person would be homosexual, sometimes heterosexual.

Some other causes of homosexuality for which he advocated included an inverted Oedipus complex where individuals begin to identify with their mother and take themselves as a love object. This love of one's self is defined as narcissism, and Freud thought that people who were high in the trait of narcissism would be more likely to develop homosexuality because loving the same sex is like an extension of loving oneself. The connection between narcissism and Homosexuality was later supported by an empirical study made by Rubinstein (2010). The results of the study indicated that homosexual students score higher in two measures of narcissism and lower on a self-esteem measure, compared to their heterosexual counterparts.

Freud believed treatment of homosexuality was not successful because the individual does not want to give up their homosexual identity because it brings them pleasure. He used analysis and hypnotic suggestion as treatments, but showed little success. It was through this that Freud arrived at the conclusion that homosexuality was "nothing to be ashamed of, no vice, no degradation, it cannot be classified as an illness, but a variation of sexual function." He further stated that psychoanalysts "should not promise to abolish homosexuality and make normal heterosexuality take its place," as he had concluded in his own practice that attempts to change homosexual orientations were likely to be unsuccessful. While Freud himself may have come to a more accepting view of homosexuality, his legacy in the field of psychoanalysis, especially in the United States viewed homosexuality as negative, abnormal and caused by family and developmental issues. It was these views that significantly impacted the rationale for putting homosexuality in the first and second publications of the American Psychiatric Association's DSM, conceptualizing it as a mental disorder and further stigmatizing homosexuality in society.

Havelock Ellis

Havelock Ellis (1859-1939) was working as a teacher in Australia, when he had a revelation that he wanted to dedicate his life to exploring the issue of sexuality. He returned to London in 1879 and enrolled in St. Thomas’s Hospital Medical School. He began to write, and in 1896 he co-authored Sexual Inversion with John Addington Symonds, his then lover of 6 months. The book was first published in German, and a year later it was translated into English. Their book explored homosexual relationships, and in a progressive approach for their time they refused to criminalize or pathologize the acts and emotions that were present in homosexual relationships.

Ellis disagreed with Freud on a few points regarding homosexuality, especially regarding its development. He argued that homosexuals do not have a clear cut Oedipus complex but they do have strong feelings of inadequacy, born of fears of failure and may also be afraid of relations with women. Ellis argued that the restrictions of society contributed to the development of same-sex love. He believed that homosexuality is not something people are born with, but that at some point humans are all sexually indiscriminant, and then narrow down and choose which sex acts to stick with. According to Ellis, some people choose to engage in homosexuality, while others will choose heterosexuality. He proposed that being “exclusively homosexual” is to be deviant because the person is a member of a minority and therefore statistically unusual, but that society should accept that deviations from the "normal" were harmless, and maybe even valuable. Ellis believed that psychological problems arose not from homosexual acts alone, but when someone "psychologically harms himself by fearfully limiting his own sex behavior."

Ellis is often attributed with coining the term homosexuality but in reality he despised the word because it conflated Latin and Greek roots and instead used the term invert in his published works. Soon after Sexual Inversion was published in England it was banned as lewd and scandalous. Ellis argued that homosexuality was a characteristic of a minority, and was not acquired or a vice and was not curable. He advocated changing the laws to leave those who chose to practice homosexuality at peace, because at the time it was a punishable crime. He believed societal reform could occur, but only after the public was educated. His book became a landmark in the understanding of homosexuality.

Alfred Kinsey

Alfred Charles Kinsey (1894-1956) was a sexologist who founded the Institute for Sex Research, which is now known as the Kinsey Institute for Research in Sex, Gender and Reproduction. His explorations into different sexual practices originated from his study of the variations in mating practices among wasps. He developed the Kinsey Scale, which measures sexual orientation in ranges from 0 to 6 with 0 being exclusively heterosexual and 6 being exclusively homosexual. His findings indicated that there was great variability in sexual orientations. Kinsey published books titled Sexual Behavior in the Human Male, and Sexual Behavior in the Human Female, which brought him a lot of fame and controversy. The prevailing approach to homosexuality at the time was to pathologize and attempt to change homosexuals. Kinsey's book demonstrated that homosexuality was more common than was assumed, suggesting that these behaviors are normal and part of a continuum of sexual behaviors.

The Diagnostic and Statistical Manual

The social, medical and legal approach to homosexuality ultimately led for its inclusion in the first and second publications of the American Psychiatric Association’s Diagnostic and Statistical Manual (DSM). This served to conceptualize homosexuality as a mental disorder and further stigmatize homosexuality in society. However, the evolution in scientific study and empirical data from Kinsey, Evelyn Hooker and others confronted these beliefs, and by the 1970s psychiatrists and psychologists were radically altering their views on homosexuality. Tests such as the Rorschach, Thematic Apperception Test (TAT) and the Minnesota Multiphasic Personality Inventory (MMPI) indicated that homosexual men and women were not distinguishable from heterosexual men and women in functioning. These studies failed to support the previous assumptions that family dynamics, trauma and gender identity were factors in the development of sexual orientation. Due to lack of supporting data, as well as exponentially increasing pressure from the advocates of homosexuality, the Board of Directors for the American Psychiatric Association voted to remove homosexuality as a mental disorder from the DSM in 1973. See DSM-III. After considerable delay and controversy, DSM-III-R (1987) dropped homosexuality as a listed mental disorder.

Major areas of psychological research

Causes of homosexuality

আরও দেখুন: Biology and sexual orientation ও Environment and sexual orientation

Numerous different theories have been proposed to explain the development of homosexuality, but there is so far no universally accepted account of the origins of a homosexual sexual orientation.

বৈষম্য

আরও দেখুন: Homophobia ও Societal attitudes toward homosexuality

সমকামি বিরোধী এ মনোভাব এবং আচরণ ( যাকে মাঝে মাঝে 'হোমোফোবিয়া' বা 'হেটোরোসেক্সুয়াল' নামে অভিহিত করা হয়) মনস্তাত্ত্বিক গবেষণাগুলির একটি বিষয় হয়ে দাঁড়িয়েছে। এই ধরনের গবেষণাগুলোতে; সমাজে নারী সমকামির তুলনায় পুরুষ সমকামীদের প্রতি যে বৈরী আচরণ সচরাচর পরিলক্ষিত হয়, তাই ফুটে উঠেছে। যারা সমকামীদের ব্যক্তিগত ভাবে জানে না, সমকামী-বিরোধী মনোভাব মুলত তাদের মধ্যেই দেখা যায়। There is also a high risk for anti-gay bias in psychotherapy with lesbian, gay, and bisexual clients.এক গবেষণায় দেখা গেছে যে, প্রায় অর্ধেক নমুনা মৌখিকভাবে বা শারীরিক সহিংসতার শিকার ছিল কারণ তাদের যৌন অভিযোজন, সাধারণত পুরুষদের দ্বারা সংঘটিত হয়। এই ধরনের হয়রানি হতাশা, উদ্বেগ, ক্রোধ, এবং পোস্ট ট্রমাটিক চাপের উপসর্গগুলির উচ্চ স্তরের সাথে সম্পর্কিত One study found that nearly half of its sample had been the victim of verbal or physical violence because of their sexual orientation, usually committed by men. Such victimization is related to higher levels of depression, anxiety, anger, and symptoms of post-traumatic stress. Research suggests that parents who respond negatively to their child's sexual orientation tended to have lower self-esteem and negative attitudes toward women, and that "negative feelings about homosexuality in parents decreased the longer they were aware of their child's homosexuality."

উপরন্তু, গবেষণায় প্রস্তাবনা করা হয়েছে যে, "যেসব পরিবার তাদের পারিবারিক ঐতিহ্যগত মূল্যবোধ অনুসরণ করে, ধর্মীয় রীতিনীতি অনুসরণ করে, বিবাহ এবং বাচ্চাকাচ্চা থাকার প্রতি জোর দেয়, সেসব পরিবারের; কম ঐতিহ্য অনুসরণ করা পরিবারের তুলনায়; সমকামিতাকে গ্রহণ করার মানসিকতা কম দেখা যায়।" তবে আরো একটি গবেষণা থেকে দেখা গিয়েছে, এটি সর্বজনীন নয়। অর্থাৎ এর উল্টোটাও হতে পারে। উদাহরণস্বরূপ, চানা এটেনংফ এবং কোলেট ডাইয়েট কর্তৃক APA's Psychology of Religion & Spirituality নামক জার্নালে একটি গবেষণা প্রকাশিত হয়। সেখানে দেখা গেছে যে; ধর্মীয় পরিবারের সদস্যরা উল্টো তাদের কোনো সদস্যের ভিন্ন যৌন অভিমুখিতাকে ধর্মীয় মুল্যবোধ ও ধর্মীয় গ্রন্থ দ্বারাই স্বীকার বা সমর্থন করছেন। যেমনঃ একজন ক্যাথলিক মা, তার সমকামি পুত্রের অভিব্যক্তি নিয়ে কথা বলতে গিয়ে বলেন, "স্রষ্টার সকল নির্দেশনার উপরে নির্দেশনা হলো ভালোবাসা"। একইভাবে একজন মেথোডিস্ট মা তার প্রিয় সমকামী পুত্রের সাথে এবিষয়ে কথা বলতে গিয়ে যীশুকেই তথ্যসুত্র হিসেবে ব্যবহার করেন। তিনি বলেন, "আমি যীশাসের বার্তা পড়ি, তার বার্তায় তিনি ভালোবাসার কথা বলেছেন, ক্ষমার কথা বলেছেন, এবং আমি মনে করি না, একজন লোককে কখনোই তার ভালোবাসামুলক কাজের জন্য শাস্তি দেওয়া যায়।।" একই বক্তব্য প্রতিফলিত হয়েছে একজন ধার্মিক মরমন পিতার দ্বারা, তিনি বলেছেন, "যদি তুমি কাওকে ভালোবাসো, তাহলে সেটা স্বীকার করে নেওয়াই সবচেয়ে বেশি যৌক্তিক।"”.

Mental health issues

Psychological research in this area includes examining mental health issues (including stress, depression, or addictive behavior) faced by gay and lesbian people as a result of the difficulties they experience because of their sexual orientation, physical appearance issues, eating disorders, or gender atypical behavior.

• Psychiatric disorders: In a Dutch study, gay men reported significantly higher rates of mood and anxiety disorders than straight men, and lesbians were significantly more likely to experience depression (but not other mood or anxiety disorders) than straight women.
• Physical appearance and eating disorders: Gay men tend to be more concerned about their physical appearance than straight men. Lesbian women are at a lower risk for eating disorders than heterosexual women.
• Gender atypical behavior: While this is not a disorder, gay men may face difficulties due to being more likely to display gender atypical behavior than heterosexual men. The difference is less pronounced between lesbians and straight women.
• Minority stress: Stress caused from a sexual stigma, manifested as prejudice and discrimination, is a major source of stress for people with a homosexual orientation. Sexual-minority affirming groups and gay peer groups help counteract and buffer minority stress.
• Ego-dystonic sexual orientation: Conflict between religious identity and sexual orientation identity can cause severe stress, causing some people to want to change their sexual orientation. Sexual orientation identity exploration can help individuals evaluate the reasons behind the desire to change and help them resolve the conflict between their religious and sexual identity, either through sexual orientation identity reconstruction or affirmation therapies. Therapists are to offer acceptance, support, and understanding of clients and the facilitation of clients’ active coping, social support, and identity exploration and development, without imposing a specific sexual orientation identity outcome. Ego-dystonic sexual orientation is a disorder where a person wishes their sexual orientation were different because of associated psychological and behavioral disorders.
• Sexual relationship disorder: People with a homosexual orientation in mixed-orientation marriages may struggle with the fear of the loss of their marriage. Therapists should focus exploring the underlying personal and contextual problems, motivations, realities, and hopes for being in, leaving, or restructuring the relationship and should not focus solely on one outcome such as divorce or marriage. Sexual relationship disorder is a disorder where the gender identity or sexual orientation interferes with maintaining or forming of a relationship.

Suicide

আরও দেখুন: Suicide ও Suicide among LGBT youth

The likelihood of suicide attempts is higher in both gay males and lesbians, as well as bisexual individuals of both sexes, when compared to their heterosexual counterparts. The trend of having a higher incident rate among females encompasses lesbians or bisexual females; when compared with homosexual or bisexual males, lesbians are more likely to attempt suicide.

Studies dispute the exact difference in suicide rate compared to heterosexuals with a minimum of 0.8–1.1 times more likely for females and 1.5–2.5 times more likely for males. The higher figures reach 4.6 times more likely in females and 14.6 times more likely in males.

Race and age play a factor in the increased risk. The highest ratios for males are attributed to young Caucasians. By the age of 25, their risk is more than halved; however, the risk for black gay males at that age steadily increases to 8.6 times more likely. Over a lifetime, the increased likelihoods are 5.7 times for white and 12.8 for black gay and bisexual males. Lesbian and bisexual females have the opposite trend, with fewer attempts during the teenager years compared to heterosexual females. Through a lifetime, the likelihood for Caucasian females is nearly triple that of their heterosexual counterparts; however, for black females there is minimal change (less than 0.1 to 0.3 difference), with heterosexual black females having a slightly higher risk throughout most of the age-based study.

Gay and lesbian youth who attempt suicide are disproportionately subject to anti-gay attitudes, often have fewer skills for coping with discrimination, isolation, and loneliness, and were more likely to experience family rejection than those who do not attempt suicide. Another study found that gay and bisexual youth who attempted suicide had more feminine gender roles, adopted a non-heterosexual identity at a young age and were more likely than peers to report sexual abuse, drug abuse, and arrests for misconduct. One study found that same-sex sexual behavior, but not homosexual attraction or homosexual identity, was significantly predictive of suicide among Norwegian adolescents.

Sexual orientation identity development

মূল নিবন্ধ: Sexual orientation identity

• Coming out: Many gay, lesbian and bisexual people go through a "coming out" experience at some point in their lives. Psychologists often say this process includes several stages "in which there is an awareness of being different from peers ('sensitization'), and in which people start to question their sexual identity ('identity confusion'). Subsequently, they start to explore practically the option of being gay, lesbian or bisexual and learn to deal with the stigma ('identity assumption'). In the final stage, they integrate their sexual desires into a position understanding of self ('commitment')." However, the process is not always linear and it may differ for lesbians, gay men and bisexual individuals.
• Different degrees of coming out: One study found that gay men are more likely to be out to friends and siblings than to co-workers, parents, and more distant relatives.
• Coming out and well-being: Same-sex couples who are openly gay are more satisfied in their relationships. For women who self-identify as lesbian, the more people know about her sexual orientation, the less anxiety, more positive affectivity, and greater self-esteem she has.
• Rejection of gay identity: Various studies report that for some religious people, rejecting a gay identity appears to relieve the distress caused by conflicts between religious values and sexual orientation. After reviewing the research, Judith Glassgold, chair of the American Psychological Association sexuality task force, said some people are content in denying a gay identity and "there is no clear evidence of harm".

Fluidity of sexual orientation

The American Psychiatric Association (APA) states that "some people believe that sexual orientation is innate and fixed; however, sexual orientation develops across a person’s lifetime". In a statement issued jointly with other major American medical organizations, the American Psychological Association states that "different people realize at different points in their lives that they are heterosexual, gay, lesbian, or bisexual". A report from the Centre for Addiction and Mental Health states that, "For some people, sexual orientation is continuous and fixed throughout their lives. For others, sexual orientation may be fluid and change over time". Lisa Diamond's study "Female bisexuality from adolescence to adulthood" suggests that there is "considerable fluidity in bisexual, unlabeled, and lesbian women's attractions, behaviors, and identities".

Parenting

আরও দেখুন: LGBT parenting

LGBT parenting is when lesbian, gay, bisexual, and transgender (LGBT) people are parents to one or more children, either as biological or non-biological parents. Gay men have options which include "foster care, variations of domestic and international adoption, diverse forms of surrogacy (whether "traditional" or gestational), and kinship arrangements, wherein they might coparent with a woman or women with whom they are intimately but not sexually involved." LGBT parents can also include single parents; to a lesser extent, the term sometimes refers to parents of LGBT children.

In the 2000 U.S. Census, 33 percent of female same-sex couple households and 22 percent of male same-sex couple households reported at least one child under eighteen living in their home. Some children do not know they have an LGBT parent; coming out issues vary and some parents may never come out to their children. adoption by LGBT couples and LGBT parenting in general may be controversial in some countries. In January 2008, the European Court of Human Rights ruled that same-sex couples have the right to adopt a child. In the U.S., LGB people can legally adopt, as individuals, in all fifty states.

Although it is sometimes asserted in policy debates that heterosexual couples are inherently better parents than same-sex couples, or that the children of lesbian or gay parents fare worse than children raised by heterosexual parents, those assertions are not supported by scientific research literature. There is ample evidence to show that children raised by same-gender parents fare as well as those raised by heterosexual parents. Much research has documented the lack of correlation between parents' sexual orientation and any measure of a child's emotional, psychosocial, and behavioral adjustment. These data have demonstrated no risk to children as a result of growing up in a family with one or more gay parents. No research supports the widely held conviction that the gender of parents influences the well-being of the child. If gay, lesbian, or bisexual parents were inherently less capable than otherwise comparable heterosexual parents, their children would present more poorly regardless of the type of sample. This pattern has not been observed. Given the consistent failures in this research literature to disprove the null hypothesis, the burden of empirical proof is on those who argue that the children of sexual minority parents are worse off than the children of heterosexual parents.

Professor Judith Stacey, of New York University, stated: “Rarely is there as much consensus in any area of social science as in the case of gay parenting, which is why the American Academy of Pediatrics and all of the major professional organizations with expertise in child welfare have issued reports and resolutions in support of gay and lesbian parental rights”. These organizations include the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, the American Psychiatric Association, the American Psychological Association, the American Psychoanalytic Association, the National Association of Social Workers, the Child Welfare League of America, the North American Council on Adoptable Children, and Canadian Psychological Association (CPA). CPA is concerned that some persons and institutions are misinterpreting the findings of psychological research to support their positions, when their positions are more accurately based on other systems of belief or values.

The vast majority of families in the United States today are not the "middle-class family with a bread-winning father and a stay-at-home mother, married to each other and raising their biological children" that has been viewed as the norm. Since the end of the 1980s, it has been well established that children and adolescents can adjust just as well in nontraditional settings as in traditional settings.

Psychotherapy

Most people with a homosexual orientation who seek psychotherapy do so for the same reasons as straight people (stress, relationship difficulties, difficulty adjusting to social or work situations, etc.); their sexual orientation may be of primary, incidental, or no importance to their issues and treatment. Regardless of the issue that psychotherapy is sought for, there is a high risk of anti-gay bias being directed at non-heterosexual clients.

Relationship counseling

আরও দেখুন: Relationship counseling

Most relationship issues are shared equally among couples regardless of sexual orientation, but LGBT clients additionally have to deal with homophobia, heterosexism, and other societal oppressions. Individuals may also be at different stages in the coming out process. Often, same-sex couples do not have as many role models for successful relationships as opposite-sex couples. There may be issues with gender-role socialization that does not affect opposite-sex couples.

A significant number of men and women experience conflict surrounding homosexual expression within a mixed-orientation marriage. Therapy may include helping the client feel more comfortable and accepting of same-sex feelings and to explore ways of incorporating same-sex and opposite-sex feelings into life patterns. Although a strong homosexual identity was associated with difficulties in marital satisfaction, viewing the same-sex activities as compulsive facilitated commitment to the marriage and to monogamy.

Gay affirmative psychotherapy

মূল নিবন্ধ: Gay affirmative psychotherapy

Gay affirmative psychotherapy is a form of psychotherapy for gay and lesbian clients which encourages them to accept their sexual orientation, and does not attempt to change their sexual orientation to heterosexual, or to eliminate or diminish their same-sex desires and behaviors. The American Psychological Association (APA) and the British Psychological Society offer guidelines and materials for gay affirmative psychotherapy. Practitioners of gay affirmative psychotherapy states that homosexuality or bisexuality is not a mental illness, and that embracing and affirming gay identity can be a key component to recovery from other mental illnesses or substance abuse. Some people may find neither gay affirmative therapy nor conversion therapy appropriate, however. Clients whose religious beliefs are inconsistent with homosexual behavior may require some other method of integrating their conflicting religious and sexual selves.

Sexual orientation identity exploration

আরও দেখুন: Ego-dystonic sexual orientation

The APA recommends that if a client wants treatment to change his sexual orientation, the therapist should explore the reasons behind the desire, without favoring any particular outcome. The therapist should neither promote nor reject the idea of celibacy, but help the client come to their own decisions by evaluating the reasons behind the patient's goals. One example of sexual orientation identity exploration is Sexual Identity Therapy.

After exploration, a patient may proceed with sexual orientation identity reconstruction, which helps a patient reconstruct sexual orientation identity. Psychotherapy, support groups, and life events can influence identity development; similarly, self-awareness, self-conception, and identity may evolve during treatment. It can change sexual orientation identity (private and public identification, and group belonging), emotional adjustment (self-stigma and shame reduction), and personal beliefs, values and norms (change of religious and moral belief, behavior and motivation). Some therapies include Gender Wholeness Therapy.

The American Psychiatric Association states in their official statement release on the matter: "The potential risks of 'reparative therapy' are great and include depression, anxiety, and self-destructive behavior, since therapist alignment with societal prejudices against homosexuality may reinforce self-hatred already experienced by the patient. Many patients who have undergone 'reparative therapy' relate that they were inaccurately told that homosexuals are lonely, unhappy individuals who never achieve acceptance or satisfaction. The possibility that the person might achieve happiness and satisfying interpersonal relationships as a gay man or lesbian are not presented, nor are alternative approaches to dealing with the effects of societal stigmatization discussed. APA recognizes that in the course of ongoing psychiatric treatment, there may be appropriate clinical indications for attempting to change sexual behaviors."

The American Psychological Association aligns with this in a Resolution: it "urges all mental health professionals to take the lead in removing the stigma of mental illness that has long been associated with homosexual orientation" (Conger, 1975, p. 633); and "Therefore be it further resolved that the American Psychological Association opposes portrayals of lesbian, gay, and bisexual youth and adults as mentally ill due to their sexual orientation and supports the dissemination of accurate information about sexual orientation, and mental health, and appropriate interventions in order to counteract bias that is based in ignorance or unfounded beliefs about sexual orientation."

The American College of Pediatrics advises people struggling with their sexuality: "You are normal. Homosexuality is not a mental disorder. All of the major medical organizations, including The American Psychiatric Association, The American Psychological Association, and the American Academy of Pediatrics agree that homosexuality is not an illness or disorder, but a form of sexual expression. No one knows what causes a person to be gay, bisexual, or straight. There probably are a number of factors. Some may be biological. Others may be psychological. The reasons can vary from one person to another. The fact is, you do not choose to be gay, bisexual, or straight."

Developments in individual psychology

In contemporary Adlerian thought, homosexuals are not considered within the problematic discourse of the "failures of life". Christopher Shelley (1998), an Adlerian psychotherapist, published a volume of essays in the 1990s that feature Freudian, (post)Jungian and Adlerian contributions that demonstrate affirmative shifts in the depth psychologies. These shifts show how depth psychology can be utilized to support rather than pathologize gay and lesbian psychotherapy clients. The Journal of Individual Psychology, the English language flagship publication of Adlerian Psychology, released a volume in the summer of 2008 that reviews and corrects Adler's previously held beliefs on the homosexual community.

See also

• Association of Gay and Lesbian Psychiatrists
• Conversion therapy
• Ego-dystonic sexual orientation
• Minority Stress
• Homosexuality in DSM

Resources and external links

American Psychological Association

• Answers to Your Questions About Sexual Orientation and Homosexuality
• A Selected Bibliography of Lesbian, Gay, and Bisexual Concerns in Psychology
• Guidelines for Psychotherapy with Lesbian, Gay, & Bisexual Clients
• Avoiding Heterosexual Bias in Psychological Research
• Being Gay Is Just as Healthy as Being Straight
• Resolution on Sexual Orientation and Marriage
• Resolution on Sexual Orientation, Parents, and Children

American Academy of Pediatrics

• Sexual Orientation and Adolescents

British Psychological Society

• BPS Position Statement Therapies Attempting to Change Sexual Orientation
• Guidelines for psychologists working therapeutically with sexual and gender minority client

National Mental Health Association

• Factsheet: Bullying and Gay Youth
• What Does Gay Mean? How to Talk with Kids about Sexual Orientation and Prejudice

Join statements by professional bodies in the United Kingdom

• Conversion therapy: Consensus statement
• Memorandum on Conversion Therapy in the UK

এই পাতাটি the concept in intelligent design সম্পর্কে। the concept in systems theory জন্য Emergence দেখুন।

Irreducible complexity (IC) is the argument that certain biological systems cannot evolve by successive small modifications to pre-existing functional systems through natural selection. Irreducible complexity is central to the creationist concept of intelligent design, but it is rejected by the scientific community, which regards intelligent design as pseudoscience. Irreducible complexity is one of two main arguments used by intelligent design proponents, the other being specified complexity.

The theological argument from design was presented in creation science with assertions that evolution could not explain complex molecular mechanisms, and in 1993 Michael Behe, a professor of biochemistry at Lehigh University, presented these arguments in a revised version of Of Pandas and People. In his 1996 book Darwin's Black Box he called this irreducible complexity and said it made evolution through natural selection of random mutations impossible. This was based on the mistaken assumption that evolution relies on improvement of existing functions, ignoring how complex adaptations originate from changes in function, and disregarded published research. Evolutionary biologists have published rebuttals showing how systems discussed by Behe can evolve, and examples documented through comparative genomics show that complex molecular systems are formed by the addition of components as revealed by different temporal origins of their proteins.

In the 2005 Kitzmiller v. Dover Area School District trial, Behe gave testimony on the subject of irreducible complexity. The court found that "Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large."

Definitions

Michael Behe defined irreducible complexity in natural selection in his book Darwin's Black Box:

... a single system which is composed of several well-matched, interacting parts that contribute to the basic function, and where the removal of any one of the parts causes the system to effectively cease functioning.

A second definition given by Behe (his "evolutionary definition") is as follows:

An irreducibly complex evolutionary pathway is one that contains one or more unselected steps (that is, one or more necessary-but-unselected mutations). The degree of irreducible complexity is the number of unselected steps in the pathway.

Intelligent design advocate William A. Dembski gives this definition:

A system performing a given basic function is irreducibly complex if it includes a set of well-matched, mutually interacting, nonarbitrarily individuated parts such that each part in the set is indispensable to maintaining the system's basic, and therefore original, function. The set of these indispensable parts is known as the irreducible core of the system.

History

Forerunners

The argument from irreducible complexity is a descendant of the teleological argument for God (the argument from design or from complexity). This states that because certain things in nature appear very complicated, they must have been designed. William Paley famously argued, in his 1802 watchmaker analogy, that complexity in nature implies a God for the same reason that the existence of a watch implies the existence of a watchmaker. This argument has a long history, and one can trace it back at least as far as Cicero's De Natura Deorum ii.34, written in 45 BC.

Up to the 18th century

Galen (1st and 2nd centuries AD) wrote about the large number of parts of the body and their relationships, which observation was cited as evidence for creation. The idea that the interdependence between parts would have implications for the origins of living things was raised by writers starting with Pierre Gassendi in the mid-17th century and by John Wilkins (1614-1672), who wrote (citing Galen), "Now to imagine, that all these things, according to their several kinds, could be brought into this regular frame and order, to which such an infinite number of Intentions are required, without the contrivance of some wise Agent, must needs be irrational in the highest degree." In the late 17th-century, Thomas Burnet referred to "a multitude of pieces aptly joyn'd" to argue against the eternity of life. In the early 18th century, Nicolas Malebranche wrote "An organized body contains an infinity of parts that mutually depend upon one another in relation to particular ends, all of which must be actually formed in order to work as a whole", arguing in favor of preformation, rather than epigenesis, of the individual; and a similar argument about the origins of the individual was made by other 18th-century students of natural history. In his 1790 book, The Critique of Judgment, Kant is said by Guyer to argue that "we cannot conceive how a whole that comes into being only gradually from its parts can nevertheless be the cause of the properties of those parts".

19th century

Chapter XV of Paley's Natural Theology discusses at length what he called "relations" of parts of living things as an indication of their design.

Georges Cuvier applied his principle of the correlation of parts to describe an animal from fragmentary remains. For Cuvier, this related to another principle of his, the conditions of existence, which excluded the possibility of transmutation of species.

While he did not originate the term, Charles Darwin identified the argument as a possible way to falsify a prediction of the theory of evolution at the outset. In The Origin of Species (1859), he wrote, "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find out no such case." Darwin's theory of evolution challenges the teleological argument by postulating an alternative explanation to that of an intelligent designer—namely, evolution by natural selection. By showing how simple unintelligent forces can ratchet up designs of extraordinary complexity without invoking outside design, Darwin showed that an intelligent designer was not the necessary conclusion to draw from complexity in nature. The argument from irreducible complexity attempts to demonstrate that certain biological features cannot be purely the product of Darwinian evolution.

In the late 19th century, in a dispute between supporters of the adequacy of natural selection and those who held for inheritance of acquired characteristics, one of the arguments made repeatedly by Herbert Spencer, and followed by others, depended on what Spencer referred to as co-adaptation of co-operative parts, as in:

"We come now to Professor Weismann's endeavour to disprove my second thesis — that it is impossible to explain by natural selection alone the co-adaptation of co-operative parts. It is thirty years since this was set forth in "The Principles of Biology." In §166, I instanced the enormous horns of the extinct Irish elk, and contended that in this and in kindred cases, where for the efficient use of some one enlarged part many other parts have to be simultaneously enlarged, it is out of the question to suppose that they can have all spontaneously varied in the required proportions."

Darwin responded to Spencer's objections in chapter XXV of The Variation of Animals and Plants under Domestication (1868). The history of this concept in the dispute has been characterized: "An older and more religious tradition of idealist thinkers were committed to the explanation of complex adaptive contrivances by intelligent design. ... Another line of thinkers, unified by the recurrent publications of Herbert Spencer, also saw co-adaptation as a composed, irreducible whole, but sought to explain it by the inheritance of acquired characteristics."

St. George Jackson Mivart raised the objection to natural selection that "Complex and simultaneous co-ordinations … until so far developed as to effect the requisite junctions, are useless" which "amounts to the concept of "irreducible complexity" as defined by … Michael Behe".

20th century

Hermann Muller, in the early 20th century, discussed a concept similar to irreducible complexity. However, far from seeing this as a problem for evolution, he described the "interlocking" of biological features as a consequence to be expected of evolution, which would lead to irreversibility of some evolutionary changes. He wrote, "Being thus finally woven, as it were, into the most intimate fabric of the organism, the once novel character can no longer be withdrawn with impunity, and may have become vitally necessary."

In 1974 the young Earth creationist Henry M. Morris introduced a similar concept in his book Scientific Creationism, in which he wrote; "This issue can actually be attacked quantitatively, using simple principles of mathematical probability. The problem is simply whether a complex system, in which many components function unitedly together, and in which each component is uniquely necessary to the efficient functioning of the whole, could ever arise by random processes."

In 1975 Thomas H. Frazzetta published a book-length study of a concept similar to irreducible complexity, explained by gradual, step-wise, non-teleological evolution. Frazzetta wrote:

"A complex adaptation is one constructed of several components that must blend together operationally to make the adaptation "work". It is analogous to a machine whose performance depends upon careful cooperation among its parts. In the case of the machine, no single part can greatly be altered without changing the performance of the entire machine."

The machine that he chose as an analog is the Peaucellier–Lipkin linkage, and one biological system given extended description was the jaw apparatus of a python. The conclusion of this investigation, rather than that evolution of a complex adaptation was impossible, "awed by the adaptations of living things, to be stunned by their complexity and suitability", was "to accept the inescapable but not humiliating fact that much of mankind can be seen in a tree or a lizard."

In 1981, Ariel Roth, in defense of the creation-science position in the trial McLean v. Arkansas, said of "complex integrated structures": "This system would not be functional until all the parts were there ... How did these parts survive during evolution ...?"

In 1985 Cairns-Smith wrote of "interlocking": "How can a complex collaboration between components evolve in small steps?" and used the analogy of the scaffolding called centering - used to build an arch then removed afterwards: "Surely there was 'scaffolding'. Before the multitudinous components of present biochemistry could come to lean together they had to lean on something else." However, neither Muller or Cairns-Smith claimed their ideas as evidence of something supernatural.

An essay in support of creationism published in 1994 referred to bacterial flagella as showing "multiple, integrated components", where "nothing about them works unless every one of their complexly fashioned and integrated components are in place". The author asked the reader to "imagine the effects of natural selection on those organisms that fortuitously evolved the flagella ... without the concommitant [সিক] control mechanisms".

An early concept of irreducibly complex systems comes from Ludwig von Bertalanffy (1901-1972), an Austrian biologist. He believed that complex systems must be examined as complete, irreducible systems in order to fully understand how they work. He extended his work on biological complexity into a general theory of systems in a book titled General Systems Theory.

After James Watson and Francis Crick published the structure of DNA in the early 1950s, General Systems Theory lost many of its adherents in the physical and biological sciences. However, Systems theory remained popular in the social sciences long after its demise in the physical and biological sciences.

Origins

চিত্র:Darwinsblackbox.jpg

Michael Behe's controversial book Darwin's Black Box popularized the concept of irreducible complexity.

Michael Behe developed his ideas on the concept around 1992, in the early days of the 'wedge movement', and first presented his ideas about "irreducible complexity" in June 1993 when the "Johnson-Behe cadre of scholars" met at Pajaro Dunes in California. He set out his ideas in the second edition of Of Pandas and People published in 1993, extensively revising Chapter 6 Biochemical Similarities with new sections on the complex mechanism of blood clotting and on the origin of proteins.

He first used the term "irreducible complexity" in his 1996 book Darwin's Black Box, to refer to certain complex biochemical cellular systems. He posits that evolutionary mechanisms cannot explain the development of such "irreducibly complex" systems. Notably, Behe credits philosopher William Paley for the original concept (alone among the predecessors) and suggests that his application of the concept to biological systems is entirely original.

Intelligent design advocates argue that irreducibly complex systems must have been deliberately engineered by some form of intelligence.

In 2001, Michael Behe wrote: "[T]here is an asymmetry between my current definition of irreducible complexity and the task facing natural selection. I hope to repair this defect in future work." Behe specifically explained that the "current definition puts the focus on removing a part from an already functioning system", but the "difficult task facing Darwinian evolution, however, would not be to remove parts from sophisticated pre-existing systems; it would be to bring together components to make a new system in the first place". In the 2005 Kitzmiller v. Dover Area School District trial, Behe testified under oath that he "did not judge [the asymmetry] serious enough to [have revised the book] yet."

Behe additionally testified that the presence of irreducible complexity in organisms would not rule out the involvement of evolutionary mechanisms in the development of organic life. He further testified that he knew of no earlier "peer reviewed articles in scientific journals discussing the intelligent design of the blood clotting cascade," but that there were "probably a large number of peer reviewed articles in science journals that demonstrate that the blood clotting system is indeed a purposeful arrangement of parts of great complexity and sophistication." (The judge ruled that "intelligent design is not science and is essentially religious in nature".)

According to the theory of evolution, genetic variations occur without specific design or intent. The environment "selects" the variants that have the highest fitness, which are then passed on to the next generation of organisms. Change occurs by the gradual operation of natural forces over time, perhaps slowly, perhaps more quickly (see punctuated equilibrium). This process is able to adapt complex structures from simpler beginnings, or convert complex structures from one function to another (see spandrel). Most intelligent design advocates accept that evolution occurs through mutation and natural selection at the "micro level", such as changing the relative frequency of various beak lengths in finches, but assert that it cannot account for irreducible complexity, because none of the parts of an irreducible system would be functional or advantageous until the entire system is in place.

The mousetrap example

Michael Behe believes that many aspects of life show evidence of design, using the mousetrap in an analogy disputed by others.

Behe uses the mousetrap as an illustrative example of this concept. A mousetrap consists of five interacting pieces: the base, the catch, the spring, the hammer, and the hold-down bar. All of these must be in place for the mousetrap to work, as the removal of any one piece destroys the function of the mousetrap. Likewise, he asserts that biological systems require multiple parts working together in order to function. Intelligent design advocates claim that natural selection could not create from scratch those systems for which science is currently unable to find a viable evolutionary pathway of successive, slight modifications, because the selectable function is only present when all parts are assembled.

In his 2008 book Only A Theory, biologist Kenneth R. Miller challenges Behe's claim that the mousetrap is irreducibly complex. Miller observes that various subsets of the five components can be devised to form cooperative units, ones that have different functions from the mousetrap and so, in biological terms, could form functional spandrels before being adapted to the new function of catching mice. In an example taken from his high school experience, Miller recalls that one of his classmates

...struck upon the brilliant idea of using an old, broken mousetrap as a spitball catapult, and it worked brilliantly.... It had worked perfectly as something other than a mousetrap.... my rowdy friend had pulled a couple of parts --probably the hold-down bar and catch-- off the trap to make it easier to conceal and more effective as a catapult... [leaving] the base, the spring, and the hammer. Not much of a mousetrap, but a helluva spitball launcher.... I realized why [Behe's] mousetrap analogy had bothered me. It was wrong. The mousetrap is not irreducibly complex after all.

Other systems identified by Miller that include mousetrap components include the following:

• use the spitball launcher as a tie clip (same three-part system with different function)
• remove the spring from the spitball launcher/tie clip to create a two-part key chain (base + hammer)
• glue the spitball launcher/tie clip to a sheet of wood to create a clipboard (launcher + glue + wood)
• remove the hold-down bar for use as a toothpick (single element system)

The point of the reduction is that - in biology - most or all of the components were already at hand, by the time it became necessary to build a mousetrap. As such, it required far fewer steps to develop a mousetrap than to design all the components from scratch.

Thus, the development of the mousetrap, said to consist of five different parts which had no function on their own, has been reduced to one step: the assembly from parts that are already present, performing other functions.

The Intelligent Design argument focuses on the functionality to catch mice. It skips over the case that many, if not all, parts are already available in their own right, at the time that the need for a mousetrap arises.

Consequences of irreducible complexity

Supporters of intelligent design argue that anything less than the complete form of such a system or organ would not work at all, or would in fact be a detriment to the organism, and would therefore never survive the process of natural selection. Although they accept that some complex systems and organs can be explained by evolution, they claim that organs and biological features which are irreducibly complex cannot be explained by current models, and that an intelligent designer must have created life or guided its evolution. Accordingly, the debate on irreducible complexity concerns two questions: whether irreducible complexity can be found in nature, and what significance it would have if it did exist in nature.

Behe's original examples of irreducibly complex mechanisms included the bacterial flagellum of E. coli, the blood clotting cascade, cilia, and the adaptive immune system.

Behe argues that organs and biological features which are irreducibly complex cannot be wholly explained by current models of evolution. In explicating his definition of "irreducible complexity" he notes that:

An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional.

Irreducible complexity is not an argument that evolution does not occur, but rather an argument that it is "incomplete". In the last chapter of Darwin's Black Box, Behe goes on to explain his view that irreducible complexity is evidence for intelligent design. Mainstream critics, however, argue that irreducible complexity, as defined by Behe, can be generated by known evolutionary mechanisms. Behe's claim that no scientific literature adequately modeled the origins of biochemical systems through evolutionary mechanisms has been challenged by TalkOrigins. The judge in the Dover trial wrote "By defining irreducible complexity in the way that he has, Professor Behe attempts to exclude the phenomenon of exaptation by definitional fiat, ignoring as he does so abundant evidence which refutes his argument. Notably, the NAS has rejected Professor Behe's claim for irreducible complexity..."

Stated examples

Behe and others have suggested a number of biological features that they believe may be irreducibly complex.

Blood clotting cascade

The process of blood clotting or coagulation cascade in vertebrates is a complex biological pathway which is given as an example of apparent irreducible complexity.

The irreducible complexity argument assumes that the necessary parts of a system have always been necessary, and therefore could not have been added sequentially. However, in evolution, something which is at first merely advantageous can later become necessary. Natural selection can lead to complex biochemical systems being built up from simpler systems, or to existing functional systems being recombined as a new system with a different function. For example, one of the clotting factors that Behe listed as a part of the clotting cascade (Factor XII, also called Hageman factor) was later found to be absent in whales, demonstrating that it is not essential for a clotting system. Many purportedly irreducible structures can be found in other organisms as much simpler systems that utilize fewer parts. These systems, in turn, may have had even simpler precursors that are now extinct. Behe has responded to critics of his clotting cascade arguments by suggesting that homology is evidence for evolution, but not for natural selection.

The "improbability argument" also misrepresents natural selection. It is correct to say that a set of simultaneous mutations that form a complex protein structure is so unlikely as to be unfeasible, but that is not what Darwin advocated. His explanation is based on small accumulated changes that take place without a final goal. Each step must be advantageous in its own right, although biologists may not yet understand the reason behind all of them—for example, jawless fish accomplish blood clotting with just six proteins instead of the full ten.

Eye

মূল নিবন্ধ: Evolution of the eye

Stages in the evolution of the eye
(a) A pigment spot
(b) A simple pigment cup
(c) The simple optic cup found in abalone
(d) The complex lensed eye of the marine snail and the octopus

The eye is an example of a supposedly irreducibly complex structure, due to its many elaborate and interlocking parts, seemingly all dependent upon one another. It is frequently cited by intelligent design and creationism advocates as an example of irreducible complexity. Behe used the "development of the eye problem" as evidence for intelligent design in Darwin's Black Box. Although Behe acknowledged that the evolution of the larger anatomical features of the eye have been well-explained, he pointed out that the complexity of the minute biochemical reactions required at a molecular level for light sensitivity still defies explanation. Creationist Jonathan Sarfati has described the eye as evolutionary biologists' "greatest challenge as an example of superb 'irreducible complexity' in God's creation", specifically pointing to the supposed "vast complexity" required for transparency.

In an often misquoted passage from On the Origin of Species, Charles Darwin appears to acknowledge the eye's development as a difficulty for his theory. However, the quote in context shows that Darwin actually had a very good understanding of the evolution of the eye (see fallacy of quoting out of context). He notes that "to suppose that the eye ... could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree". Yet this observation was merely a rhetorical device for Darwin. He goes on to explain that if gradual evolution of the eye could be shown to be possible, "the difficulty of believing that a perfect and complex eye could be formed by natural selection ... can hardly be considered real". He then proceeded to roughly map out a likely course for evolution using examples of gradually more complex eyes of various species.

The eyes of vertebrates (left) and invertebrates such as the octopus (right) developed independently: vertebrates evolved an inverted retina with a blind spot over their optic disc, whereas octopuses avoided this with a non-inverted retina.

Since Darwin's day, the eye's ancestry has become much better understood. Although learning about the construction of ancient eyes through fossil evidence is problematic due to the soft tissues leaving no imprint or remains, genetic and comparative anatomical evidence has increasingly supported the idea of a common ancestry for all eyes.

Current evidence does suggest possible evolutionary lineages for the origins of the anatomical features of the eye. One likely chain of development is that the eyes originated as simple patches of photoreceptor cells that could detect the presence or absence of light, but not its direction. When, via random mutation across the population, the photosensitive cells happened to have developed on a small depression, it endowed the organism with a better sense of the light's source. This small change gave the organism an advantage over those without the mutation. This genetic trait would then be "selected for" as those with the trait would have an increased chance of survival, and therefore progeny, over those without the trait. Individuals with deeper depressions would be able to discern changes in light over a wider field than those individuals with shallower depressions. As ever deeper depressions were advantageous to the organism, gradually, this depression would become a pit into which light would strike certain cells depending on its angle. The organism slowly gained increasingly precise visual information. And again, this gradual process continued as individuals having a slightly shrunken aperture of the eye had an advantage over those without the mutation as an aperture increases how collimated the light is at any one specific group of photoreceptors. As this trait developed, the eye became effectively a pinhole camera which allowed the organism to dimly make out shapes—the nautilus is a modern example of an animal with such an eye. Finally, via this same selection process, a protective layer of transparent cells over the aperture was differentiated into a crude lens, and the interior of the eye was filled with humours to assist in focusing images. In this way, eyes are recognized by modern biologists as actually a relatively unambiguous and simple structure to evolve, and many of the major developments of the eye's evolution are believed to have taken place over only a few million years, during the Cambrian explosion. Behe asserts that this is only an explanation of the gross anatomical steps, however, and not an explanation of the changes in discrete biochemical systems that would have needed to take place.

Behe maintains that the complexity of light sensitivity at the molecular level and the minute biochemical reactions required for those first "simple patches of photoreceptor[s]" still defies explanation, and that the proposed series of infinitesimal steps to get from patches of photoreceptors to a fully functional eye would actually be considered great, complex leaps in evolution if viewed on the molecular scale. Other intelligent design proponents claim that the evolution of the entire visual system would be difficult rather than the eye alone.

Flagella

মূল নিবন্ধ: Evolution of flagella

The flagella of certain bacteria constitute a molecular motor requiring the interaction of about 40 different protein parts. Behe presents this as a prime example of an irreducibly complex structure defined as "a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning", and argues that since "an irreducibly complex system that is missing a part is by definition nonfunctional", it could not have evolved gradually through natural selection.

Reducible complexity. In contrast to Behe's claims, many proteins can be deleted or mutated and the flagellum still works, even though sometimes at reduced efficiency. In fact, the composition of flagella is surprisingly diverse across bacteria with many proteins only found in some species but not others. Hence the flagellar apparatus is clearly very flexible in evolutionary terms and perfectly able to lose or gain protein components. Further studies have shown that, contrary to claims of "irreducible complexity", flagella and related protein transport mechanisms show evidence of evolution through Darwinian processes, providing case studies in how complex systems can evolve from simpler components. Multiple processes were involved in the evolution of the flagellum, including horizontal gene transfer.

Evolution from Type Three Secretion Systems. Scientists regard this argument as having been disproved in the light of research dating back to 1996 as well as more recent findings. They point out that the basal body of the flagella has been found to be similar to the Type III secretion system (TTSS), a needle-like structure that pathogenic germs such as Salmonella and Yersinia pestis use to inject toxins into living eucaryote cells. The needle's base has ten elements in common with the flagellum, but it is missing forty of the proteins that make a flagellum work. The TTSS system negates Behe's claim that taking away any one of the flagellum's parts would prevent the system from functioning. On this basis, Kenneth Miller notes that, "The parts of this supposedly irreducibly complex system actually have functions of their own." Studies have also shown that similar parts of the flagellum in different bacterial species can have different functions despite showing evidence of common descent, and that certain parts of the flagellum can be removed without completely eliminating its functionality.

Dembski has argued that phylogenetically, the TTSS is found in a narrow range of bacteria which makes it seem to him to be a late innovation, whereas flagella are widespread throughout many bacterial groups, and he argues that it was an early innovation. Against Dembski's argument, different flagella use completely different mechanisms, and publications show a plausible path in which bacterial flagella could have evolved from a secretion system.

Biological wheels

মূল নিবন্ধ: Rotating locomotion in living systems

The wheel is also stated as an irreducibly complex structure. Contrary to some other examples, its absence in nature has been said to provide evidence against intelligent design and creationism. Molecular biologist Robin Holliday has written that the absence of biological wheels argues against creationist or intelligent design accounts of the diversity of life, because an intelligent creator—free of the limitations imposed by evolution—would be expected to deploy wheels wherever they would be of use.

Response of the scientific community

Like intelligent design, the concept it seeks to support, irreducible complexity has failed to gain any notable acceptance within the scientific community. One science writer called it a "full-blown intellectual surrender strategy".

Reducibility of "irreducible" systems

Researchers have proposed potentially viable evolutionary pathways for allegedly irreducibly complex systems such as blood clotting, the immune system and the flagellum - the three examples Behe proposed. John H. McDonald even showed his example of a mousetrap to be reducible. If irreducible complexity is an insurmountable obstacle to evolution, it should not be possible to conceive of such pathways.

Niall Shanks and Karl H. Joplin, both of East Tennessee State University, have shown that systems satisfying Behe's characterization of irreducible biochemical complexity can arise naturally and spontaneously as the result of self-organizing chemical processes. They also assert that what evolved biochemical and molecular systems actually exhibit is "redundant complexity"—a kind of complexity that is the product of an evolved biochemical process. They claim that Behe overestimated the significance of irreducible complexity because of his simple, linear view of biochemical reactions, resulting in his taking snapshots of selective features of biological systems, structures, and processes, while ignoring the redundant complexity of the context in which those features are naturally embedded. They also criticized his over-reliance of overly simplistic metaphors, such as his mousetrap.

A computer model of the co-evolution of proteins binding to DNA in the peer-reviewed journal Nucleic Acids Research consisted of several parts (DNA binders and DNA binding sites) which contribute to the basic function; removal of either one leads immediately to the death of the organism. This model fits the definition of irreducible complexity exactly, yet it evolves. (The program can be run from Ev program.)

In addition, research published in the peer-reviewed journal Nature has shown that computer simulations of evolution demonstrate that it is possible for complex features to evolve naturally.

One can compare a mousetrap with a cat in this context. Both normally function so as to control the mouse population. The cat has many parts that can be removed leaving it still functional; for example, its tail can be bobbed, or it can lose an ear in a fight. Comparing the cat and the mousetrap, then, one sees that the mousetrap (which is not alive) offers better evidence, in terms of irreducible complexity, for intelligent design than the cat. Even looking at the mousetrap analogy, several critics have described ways in which the parts of the mousetrap could have independent uses or could develop in stages, demonstrating that it is not irreducibly complex.

Moreover, even cases where removing a certain component in an organic system will cause the system to fail do not demonstrate that the system could not have been formed in a step-by-step, evolutionary process. By analogy, stone arches are irreducibly complex—if you remove any stone the arch will collapse—yet humans build them easily enough, one stone at a time, by building over centering that is removed afterward. Similarly, naturally occurring arches of stone form by the weathering away of bits of stone from a large concretion that has formed previously.

Evolution can act to simplify as well as to complicate. This raises the possibility that seemingly irreducibly complex biological features may have been achieved with a period of increasing complexity, followed by a period of simplification.

A team led by Joseph Thornton, assistant professor of biology at the University of Oregon's Center for Ecology and Evolutionary Biology, using techniques for resurrecting ancient genes, reconstructed the evolution of an apparently irreducibly complex molecular system. The April 7, 2006 issue of Science published this research.

Irreducible complexity may not actually exist in nature, and the examples given by Behe and others may not in fact represent irreducible complexity, but can be explained in terms of simpler precursors. The theory of facilitated variation challenges irreducible complexity. Marc W. Kirschner, a professor and chair of Department of Systems Biology at Harvard Medical School, and John C. Gerhart, a professor in Molecular and Cell Biology, University of California, Berkeley, presented this theory in 2005. They describe how certain mutation and changes can cause apparent irreducible complexity. Thus, seemingly irreducibly complex structures are merely "very complex", or they are simply misunderstood or misrepresented.

Gradual adaptation to new functions

মূল নিবন্ধ: Exaptation

The precursors of complex systems, when they are not useful in themselves, may be useful to perform other, unrelated functions. Evolutionary biologists argue that evolution often works in this kind of blind, haphazard manner in which the function of an early form is not necessarily the same as the function of the later form. The term used for this process is exaptation. The mammalian middle ear (derived from a jawbone) and the panda's thumb (derived from a wrist bone spur) provide classic examples. A 2006 article in Nature demonstrates intermediate states leading toward the development of the ear in a Devonian fish (about 360 million years ago). Furthermore, recent research shows that viruses play a heretofore unexpected role in evolution by mixing and matching genes from various hosts.

Arguments for irreducibility often assume that things started out the same way they ended up—as we see them now. However, that may not necessarily be the case. In the Dover trial an expert witness for the plaintiffs, Ken Miller, demonstrated this possibility using Behe's mousetrap analogy. By removing several parts, Miller made the object unusable as a mousetrap, but he pointed out that it was now a perfectly functional, if unstylish, tie clip.

Methods by which irreducible complexity may evolve

Irreducible complexity can be seen as equivalent to crossing a "valley" in a fitness landscape. A number of mathematical models of evolution have explored the circumstances under which this can happen.

Falsifiability and experimental evidence

Some critics, such as Jerry Coyne (professor of evolutionary biology at the University of Chicago) and Eugenie Scott (a physical anthropologist and former executive director of the National Center for Science Education) have argued that the concept of irreducible complexity and, more generally, intelligent design is not falsifiable and, therefore, not scientific.

Behe argues that the theory that irreducibly complex systems could not have evolved can be falsified by an experiment where such systems are evolved. For example, he posits taking bacteria with no flagellum and imposing a selective pressure for mobility. If, after a few thousand generations, the bacteria evolved the bacterial flagellum, then Behe believes that this would refute his theory.

Other critics take a different approach, pointing to experimental evidence that they believe falsifies the argument for Intelligent Design from irreducible complexity. For example, Kenneth Miller cites the lab work of Barry G. Hall on E. coli, which he asserts is evidence that "Behe is wrong".

Other evidence that irreducible complexity is not a problem for evolution comes from the field of computer science, which routinely uses computer analogues of the processes of evolution in order to automatically design complex solutions to problems. The results of such genetic algorithms are frequently irreducibly complex since the process, like evolution, both removes non-essential components over time as well as adding new components. The removal of unused components with no essential function, like the natural process where rock underneath a natural arch is removed, can produce irreducibly complex structures without requiring the intervention of a designer. Researchers applying these algorithms automatically produce human-competitive designs—but no human designer is required.

Argument from ignorance

Intelligent design proponents attribute to an intelligent designer those biological structures they believe are irreducibly complex and therefore they say a natural explanation is insufficient to account for them. However, critics view irreducible complexity as a special case of the "complexity indicates design" claim, and thus see it as an argument from ignorance and as a God-of-the-gaps argument.

Eugenie Scott, along with Glenn Branch and other critics, has argued that many points raised by intelligent-design proponents are arguments from ignorance. Behe has been accused by critics of using an "argument by lack of imagination".

False dilemma

Irreducible complexity is at its core an argument against evolution. If truly irreducible systems are found, the argument goes, then intelligent design must be the correct explanation for their existence. However, this conclusion is based on the assumption that current evolutionary theory and intelligent design are the only two valid models to explain life, a false dilemma.

Irreducible complexity in the Dover trial

While testifying during the 2005 Kitzmiller v. Dover Area School District trial, Behe conceded that there are no peer-reviewed papers supporting his claims that complex molecular systems, like the bacterial flagellum, the blood-clotting cascade, and the immune system, were intelligently designed nor are there any peer-reviewed articles supporting his argument that certain complex molecular structures are "irreducibly complex."

In the final ruling of Kitzmiller v. Dover Area School District, Judge Jones specifically singled out Behe and irreducible complexity:

• "Professor Behe admitted in "Reply to My Critics" that there was a defect in his view of irreducible complexity because, while it purports to be a challenge to natural selection, it does not actually address "the task facing natural selection." and that "Professor Behe wrote that he hoped to "repair this defect in future work..." (Page 73)
• "As expert testimony revealed, the qualification on what is meant by "irreducible complexity" renders it meaningless as a criticism of evolution. (3:40 (Miller)). In fact, the theory of evolution proffers exaptation as a well-recognized, well-documented explanation for how systems with multiple parts could have evolved through natural means." (Page 74)
• "By defining irreducible complexity in the way that he has, Professor Behe attempts to exclude the phenomenon of exaptation by definitional fiat, ignoring as he does so abundant evidence which refutes his argument. Notably, the NAS has rejected Professor Behe's claim for irreducible complexity..." (Page 75)
• "As irreducible complexity is only a negative argument against evolution, it is refutable and accordingly testable, unlike ID [Intelligent Design], by showing that there are intermediate structures with selectable functions that could have evolved into the allegedly irreducibly complex systems. (2:15-16 (Miller)). Importantly, however, the fact that the negative argument of irreducible complexity is testable does not make testable the argument for ID. (2:15 (Miller); 5:39 (Pennock)). Professor Behe has applied the concept of irreducible complexity to only a few select systems: (1) the bacterial flagellum; (2) the blood-clotting cascade; and (3) the immune system. Contrary to Professor Behe's assertions with respect to these few biochemical systems among the myriad existing in nature, however, Dr. Miller presented evidence, based upon peer-reviewed studies, that they are not in fact irreducibly complex." (Page 76)
• "...on cross-examination, Professor Behe was questioned concerning his 1996 claim that science would never find an evolutionary explanation for the immune system. He was presented with fifty-eight peer-reviewed publications, nine books, and several immunology textbook chapters about the evolution of the immune system; however, he simply insisted that this was still not sufficient evidence of evolution, and that it was not "good enough." (23:19 (Behe))." (Page 78)
• "We therefore find that Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large. (17:45-46 (Padian); 3:99 (Miller)). Additionally, even if irreducible complexity had not been rejected, it still does not support ID as it is merely a test for evolution, not design. (2:15, 2:35-40 (Miller); 28:63-66 (Fuller)). We will now consider the purportedly "positive argument" for design encompassed in the phrase used numerous times by Professors Behe and Minnich throughout their expert testimony, which is the "purposeful arrangement of parts." Professor Behe summarized the argument as follows: We infer design when we see parts that appear to be arranged for a purpose. The strength of the inference is quantitative; the more parts that are arranged, the more intricately they interact, the stronger is our confidence in design. The appearance of design in aspects of biology is overwhelming. Since nothing other than an intelligent cause has been demonstrated to be able to yield such a strong appearance of design, Darwinian claims notwithstanding, the conclusion that the design seen in life is real design is rationally justified. (18:90-91, 18:109-10 (Behe); 37:50 (Minnich)). As previously indicated, this argument is merely a restatement of the Reverend William Paley's argument applied at the cell level. Minnich, Behe, and Paley reach the same conclusion, that complex organisms must have been designed using the same reasoning, except that Professors Behe and Minnich refuse to identify the designer, whereas Paley inferred from the presence of design that it was God. (1:6- 7 (Miller); 38:44, 57 (Minnich)). Expert testimony revealed that this inductive argument is not scientific and as admitted by Professor Behe, can never be ruled out. (2:40 (Miller); 22:101 (Behe); 3:99 (Miller))." (Pages 79–80)

Additional references

• Behe, Michael (১৯৯৬)। Darwin's Black Box। New York: The Free Press। আইএসবিএন 0-684-83493-6। ওসিএলসি 34150540। উদ্ধৃতি টেমপ্লেট ইংরেজি প্যারামিটার ব্যবহার করেছে (link)
• Denton, Michael (১৯৮৬)। Evolution: A Theory in Crisis। Bethesda, Md: Adler & Adler। আইএসবিএন 0-917561-05-8। উদ্ধৃতি টেমপ্লেট ইংরেজি প্যারামিটার ব্যবহার করেছে (link)
• Macnab RM (২০০৪)। "Type III flagellar protein export and flagellar assembly"। Biochim Biophys Acta। 1694 (1–3): 207–17। ডিওআই:10.1016/j.bbamcr.2004.04.005। পিএমআইডি 15546667। উদ্ধৃতি টেমপ্লেট ইংরেজি প্যারামিটার ব্যবহার করেছে (link)
• Ruben, J.A.; Jones, T.D.; Geist, N.R.; Hillenius, W.J. (নভেম্বর ১৪, ১৯৯৭)। "Lung Structure and Ventilation in Theropod Dinosaurs and Early Birds"। Science। 278 (5341): 1267–70। ডিওআই:10.1126/science.278.5341.1267। বিবকোড:1997Sci...278.1267R। উদ্ধৃতি টেমপ্লেট ইংরেজি প্যারামিটার ব্যবহার করেছে (link)
• Sunderland, Luther D. (March 1976). Miraculous Design in Woodpeckers. Creation Research Society Quarterly.
• Testing Darwin Discover Magazine Vol. 26 No. 02 |February 2005

External links

Supportive

• Michael J. Behe home page
• About Irreducible Complexity Discovery Institute
• Behe's Reply to his Critics (pdf)
• How to Explain Irreducible Complexity -- A Lab Manual Discovery Institute
• Institute for Creation Research (pdf)
• Irreducible Complexity: Definition & Evaluation by Craig Rusbult, Ph.D.
• Irreducible Complexity Revisited (pdf)

Critical

• Behe, Biochemistry, and the Invisible Hand
• Darwin vs. Intelligent Design (again), by H. Allen Orr (review of Darwin's Black Box)
• Devolution: Why intelligent design isn't (The New Yorker)
• Does irreducible complexity imply Intelligent Design? by Mark Perakh
• Evolution of the Eye (Video) Zoologist Dan-Erik Nilsson demonstrates eye evolution through intermediate stages with working model. (PBS)
• Facilitated Variation
• Himma, Kenneth Einar. Design Arguments for the Existence of God. Internet Encyclopedia of Philosophy: 2. Contemporary Versions of the Design Argument, a. The Argument from Irreducible Biochemical Complexity
• Kitzmiller vs. Dover transcripts
• Miller, Kenneth R. textbook website
• Miller's "The Flagellum Unspun: The Collapse of Irreducible Complexity"
• Talk.origins archive (see talk.origins)
• TalkDesign.org (sister site to talk.origins archive on intelligent design)
• The bacterial flagellar motor: brilliant evolution or intelligent design? Matt Baker, ABC Science, 7 July 2015
• Unlocking cell secrets bolsters evolutionists (Chicago Tribune)