In his book, Initiative: Human Agency and Society, Machan claims both that free will exists and that it is the necessary basis for morality and successful social practices. He supposes that causal determinism is a threat to our capacities for reason, morality, effective action, justice, and originality, and that human beings are (fortunately!) singular exceptions to determinism by virtue of being self-caused causers. Although he contends that his approach is naturalistic, his notion of what counts as evidence includes appeals to the subjective feeling of free will, which as Daniel Wegner makes abundantly clear in his book The Illusion of Conscious Will (see above in Section 1), is highly unreliable evidence of anything except what we feel to be the case. Machan condemns most contemporary science and social theory for failing to appreciate what he takes to be the obvious and necessary fact of contra-causal human freedom ("initiative"), but those scientists and philosophers he cites as being on his side of the argument are few and far between compared to the majority of mainstream thinkers who more or less accept naturalism (although most have yet to state its implications explicitly, with the exception of those cited in Section I above).
Henry P. Stapp
"Attention, intention, and will in quantum physics," in The Volitional Brain, Libet, Freeman, and Sutherland, eds. Imprint Academic, 1999: "It has become now widely appreciated that assimilation by the general public of this ‘scientific’ view, according to which each human being is basically a mechanical robot, is likely to have a significant and corrosive impact on the moral fabric of society… [involving] the growing tendency of people to exonerate themselves by arguing that it is not 'I’ who is at fault, but some mechanical process within…" quoted in my "Fear of Mechanism" same volume, pp. 281-282. See this book also for a piece by Benjamin Libet defending a neuroscientific account of free will, which also gets critiqued by me in "Fear of Mechanism".
Dr. Frederick K. Goodwin, Dr. Frederick J. Frese, James Q. Wilson, Charles Krauthammer
Conference on Neuroscience and the Human Spirit, 1998: As Goodwin, organizer of the conference puts it in his opening remarks, the question at the core of the gathering is "Do …scientific advances challenge the first principles that the majority of our citizens believe provide the very foundation upon which our civilization rests – free will and the capacity to make moral choices?" Put otherwise: "Does this growing understanding of genetic and environmental influences on human behavior leave any room for free will?" And again: "How can the ever-mounting discoveries of biological, genetic, and environmental factors shaping human behavior be integrated into our culture without contributing to further erosion of individual responsibility?" Goodwin expresses the intuition behind the threat: "To the extent that our choices are not truly free, it would seem that we have less moral responsibility for them."
Other variants of the threat come up throughout the conference, for instance, the threat to personhood: "…the more neuroscientists discover that our brains function in a manner analogous to some sort of biochemical robot, the more imperative it is that we as human beings not lose contact with that essence that prevents us from seeing ourselves as mere automatons" (Dr. Frederick J. Frese). Science may also threaten the basis for imposing accountability: "…will our greater ability to predict crime reduce our ability to condemn it?" (James Q. Wilson). The political and cultural battle lines of the threat are most vividly drawn by Charles Krauthammer: "…there’s an ideological agenda…, a sophisticated, elite culture that finds such notions as free will and human autonomy not just tiresome but [similar] to old religious superstitions. Instead, it would like to bring us all to the sophistication of a brave new mechanistic world in which moral judgments are personal and thus suspect; in which individual and personal responsibility is lost in a fog of a therapeutic culture whose ultimate sin is to be judgmental and whose most cherished ideal is healing." Krauthammer is of course quite wrong on all these counts, since personal responsibility is quite sustainable within naturalism. See for instance my Fear of Mechanism and Materialism and Morality.
Rychlak, R.J. and Rychlak, J.F.
"Free will is a verifiable assumption: a reply to Garrett and Viney," New Ideas in Psychology, V8 #1, 1990, 43-51: "To move from the present position on this question [that is, to accept a fully causal account of human behavior] would be to abandon the assumption that humans are endowed with free will. Were the Law to abandon its belief in free will, the criminal justice system as we know it would collapse" p. 46. "Free will as an assumption concerning human behavior is as scientifically verifiable as any of the other assumptions that psychologists make concerning human behavior. It is time for psychologists to take this concept seriously" (p. 50). But, one wonders, why don't psychologists, for the most part, take it seriously? See Wegner's book, The Illusion of Conscious Will (discussed in Section 1), to see why not.
Man, Beast and Zombie: What Science Can and Cannot Tell Us About Human Nature, defends human specialness against science, saying that we can transcend both nature and nurture. While it's true human beings have the almost limitless creative capacity to consider their situation from all sorts of angles, this capacity stems entirely from nature and nurture, and the way we actually use this capacity is entirely a function of past and surrounding circumstances. Malik takes issue with my characterization of his thesis, and I reply in the Yahoo Evol-Psych group. There's certainly much more to be said about the status of human exceptionalism.