Wednesday, June 22, 2011

Genes vs. ambiente vs. livre-arbitrio

Genetic Determinism vs. Parental Irrelevantism, por Bryan Caplan:

Still, if someone were to caricature my position as "parental irrelevantism," I would take no offense.  It's an inaccurate summary of my position, but not wildly inaccurate.  I really do think that parents' influence on kids' long-run outcomes is greatly over-rated.  Calling me a "parental irrelevantist" is arguably a useful simplification of my actual, subtler position.

Unfortunately, when people caricature me, they usually try to pin a totally inaccurate label on me: "genetic determinist."  I am not a genetic determinist.  Not even close.  The simplest twin study conclusively disproves genetic determinism.  Identical twins are genetically identical, but they're not identical for any complex trait.  Identical twins don't have the same lifespan, the same IQ, the same happiness, the same friends, or the same income - even when they're raised together.  Since genetic determinism predicts that identical twins will be identical for all traits, genetic determinism is demonstrably false.

Not only am I not a genetic determinist; I'm not a determinist of any kind.  The empirical evidence in favor of my own free will is overwhelming: Introspection reveals free will to me during my every waking moment.  There are many reasons why identical twins aren't phenotypically identical.  But free will has to be the most overlooked.  As I write in Selfish Reasons to Have More Kids:
I doubt that scientists will ever account for my sons' differences, because I think their primary source is free will. Despite genes, despite family, despite everything, human beings always have choices--and when we can make different choices, we often do. Some choices are moment-to-moment: To keep working or give up, lie or tell the truth, abandon or defend your views on immigration policy. Other choices are cumulative: You can't change your weight, education, or income by snapping your fingers, but in the long run they depend on diet, study, and effort--all of which you're free to choose.
E também o primeiro comentário ao post:
I think free-will is most often ignored because from the point of view of studying human behavior, it is entirely uninteresting. As students of human behaviors, what is interesting to us is what we can study and predict. It is how we can take the unknown, the unpredictable or the incomprehensible and turn it into the known, the predictable and the understood. The bounds of free-will are what we can study scientifically. Free will itself is 1-R^2: A topic best left to philosophy.


nuno vieira matos said...

Máquinas iguais vão ter diferentes performances. Qualquer processo assenta em variabilidade (maior ou menor). O facto de gémeos idênticos poderem seguir vias diferentes não prove per si a existência de um 'livre arbítrio'. A incerteza da previsão terá mais relacionada com a complexidade do sistema homem que com uma qualquer noção filosófica.

De qualquer forma, existem relatos de gémeos verdadeiros, separados à nascença que vão ter vidas muito semelhantes, ou relacionarem-se com pessoas semelhantes.

PR said...

Não há contradição entre determinismo e livre-arbítrio. Na verdade, o determinismo é condição necessária (embora não suficiente) para que possa haver livre arbítrio. Se as minhas decisões são aleatórias, então dificilmente poderei dizer que fui eu que as tomei.