Pinker magnificently reconciles determinism with morality.

As science advances and explanations of behavior become less fanciful, the Specter of Creeping Exculpation, as Dennet calls it, will loom larger. Without a clearer moral philosophy, any cause of behavior could be taken to undermine free will and hence moral responsibility. Science is guaranteed to appear to eat away at the will, regardless of what it finds, because the scientific mode of explanation cannot accommodate the mysterious notion of uncaused causation that underlies the will. If scientists wanted to show that people had free will, what would they look for? Some random neural event that the rest of the brain amplifies into a signal triggering behavior? But that random event does not fit the concept of free will any more than a lawful one does, and could not serve as the long-sought locus of moral responsibility. We would not find someone guilty if his finger pulled the trigger when it was mechanically connected to a roulette wheel; why should it be any different if the roulette wheel is inside his skull? The same problem arises for another unpredictable cause that has been suggested as the source of free will, chaos theory, in which according to the cliché, a butterfly’s flutter can set off a cascade of events culminating in a hurricane. A fluttering in the brain that causes a hurricane of behavior, if it were ever found, would still be a cause of behavior and would not fit the concept of uncaused free will that underlies moral responsibility.

Either we dispense with all morality as an unscientific superstition, or we find a way to reconcile causation (genetic or otherwise) with responsibility and free will. […] Like many philosophers, I believe that science and ethics are two self-contained systems played out among the same entities in the world, just as poker and bridge are different games played with the same fifty-two-card deck. The science game treats people as material objects, and its rules are the physical processes that cause behavior through natural selection and neurophysiology. The ethics game treats people as equivalent, sentient, rational, free-willed agents, and its rules are the calculus that assigns moral value to behavior through the behavior’s inherent nature or its consequences.

Free will is an idealization of human beings that makes the ethics game playable. Euclidean geometry requires idealizations like infinite straight lines and perfect circles, and its deductions are sound and useful even though the world does not really have infinite straight lines or perfect circles. The world is close enough to the idealization that the theorems can usefully be applied. Similarly, ethical theory requires idealizations like free, sentient, rational, equivalent agents whose behavior is uncaused, and its conclusions can be sound and useful even though the world, as seen by science, does not really have uncaused events. As long as there is no outright coercion or gross malfunction of reasoning, the world is close enough to the idealization of free will that moral theory can meaningfully be applied to it.

Science an morality are separate spheres of reasoning. Only re recognizing them as separate can we have them both. If discrimination is wrong only if group averages are the same, if war and rape and greed are wrong only if people are never inclined towards them, if people are responsible for their actions only if the actions are mysterious, then either scientists must be prepared to fudge their data or all of us must be prepared to give up our values. […]

[…] In the latest twist in the human-nature morality play, a chromosomal marker for homosexuality in some men, the so-called gay gene, was identified by the geneticist Dean Hamer. To the bemusement of Science for the People, this time it is the genetic explanation that is politically correct. Supposedly it refutes right-wingers like Dan Quayle, who had said that homosexuality “is more of a choice than a biological situation. It is a wrong choice.” The gay gene has been used to argue that homosexuality is not a choice for which gay people can be held responsible but an involuntary orientation they just can’t help. But the reasoning is dangerous. The gay gene could just as easily be said to influence some people to choose homosexuality. And like all good science, Hamer’s result might be falsified someday, and then where would we be? Conceding that bigotry against gay people is OK after all? The argument against persecuting gay people must be made not in terms of the gay gene or the gay brain but in terms of people’s right to engage in private consensual acts without discrimination or harassment.

[…] As one humanistic scholar lucidly put it in an Internet posting, does [my recurring metaphor of the mind as a machine, of people as robots] not render human experience invalid, reifying a model of relating based on an I-It relationship, and delegitimating all other forms of discourse with fundamentally destructive consequences to society? Only if one is so literal-minded that one cannot shift among different stances in conceptualizing people for different purposes. A human being is simultaneously a machine and a sentient free agent, depending on the purpose of the discussion, just as he is also a taxpayer, an insurance salesman, a dental patient, and two hundred pounds of ballast on a commuter airplane, depending on the purpose of the discussion. The mechanistic stance allows us to understand what makes us tick and how we fit into the physical universe. When those discussions wind down for the day, we go back to talking about each other as free and dignified human beings.