Last year I read two important books about metaphysical naturalism, which are very different from each other. I'll review the first today, Thomas Clark's brief summary (only 101 pages) of the naturalist worldview, in aid of his website and institute devoted to the subject, the Center for Naturalism (which has been much updated of late, and now has a rather elegant look and a great collection of articles). His book Encountering Naturalism: A Worldview and Its Uses has the virtue of being a good, brief introduction to naturalism as a worldview, emphasizing the utility of embracing it--personally, socially, and politically (his website continues that theme).
Encountering Naturalism is not a defense of naturalism nor a complete survey, but more like a set of predictions regarding what would be the case, or how we should act, if naturalism were true. But in the process you get a good idea of what naturalism means in terms of the nature of the world and our selves. And in that respect, in large part and on most issues, we agree. But on some important points we disagree. Some will have quibbles here and there about his history of naturalism, but nothing I consider very important. And there may be other disputable trivia like that, which I won't trouble myself with. Clark's book is also a tad redundant, which is particularly unexpected for such a short work. But that's just a matter of style. A more substantive disagreement regards how to define the supernatural, although I think here his error lies in not having or not applying a coherent or well-thought-out definition at all, which could easily be corrected by revising what he says in light of, perhaps, what I have said on that subject (see Defining the Supernatural). [I should also mention (though it is no fault of his) that since his book was published, my home page has changed, so the URL he provides on p. 97 should now read simply www.richardcarrier.info.]
More important is our slightly more significant disagreement about whether and when emotions are warranted. I think anger, for example, is more often warranted than he does, by facts he fails to consider. He occasionally commits the fallacy of thinking that by eliminating one warranting fact, he has eliminated them all. And I think forgiveness is not so readily warranted as he does, by requiring conditions he fails to consider. Cause-and-effect entails that forgiveness must be hard to earn or else it has no value, and it is only by having such value that the desire to earn it (which is caused by socially creating the need to earn it) can cause people to better themselves or right their wrongs or correct their flaws of character. And since we can't mechanically reform people with brain surgery (nor should we, even if we could), reform must come from the individual, and therefore the individual must be caused to motivate themselves. Every other approach has been scientifically demonstrated to fail.
Every expert on drug addiction, for example, will tell you the same thing: escape is impossible until the individual acknowledges they have a problem and embraces on their own the desire to change. No amount of external meddling without those conditions will have any effect. Though external influences must eventually cause those internal conditions to obtain, it is precisely by teaching the importance of personal self-reflection and responsibility (among other things) that we can cause those conditions to obtain. In this and other respects, Clark seems distrustful of American concepts of individual responsibility, as if they were rooted in superstitions about free will, when in fact our memes of individual responsibility have a solid foundation in social and psychological principles of deterministic cause and effect, without any need of a supernatural doctrine of free will. The connection between free will and American individualism is a red herring, one that overly distracts Clark in my opinion.
I explain my own rather different views of the role and importance of emotions (including the conditions of their warrant) in Sense and Goodness without God, pp. 193-208, backed by bibliographies in the latest science of emotion. Likewise, my rather different view of free will is covered there on pp. 97-117. Like Clark, I also reject the superstitious notion of absolute (or supernatural or "libertarian") free will, as in fact logically incoherent. But a coherent concept of free will is provided by modern compatibilism, which is entirely defensible even in the context of determinist physics (in fact, it is almost certainly the kind of free will we actually have, and is the only kind of free will recognized in American law).
To be honest, I have always found Clark's obsession with the free will issue almost blindingly gratuitous. This obsession is reflected in his book, where he revisits the issue again and again--in my opinion, to excess. He does this because he believes it is of central importance. I do not. I think it is almost entirely a non-issue. Every objection anyone has to determinism is based on an incoherent understanding of human will, and thus all those objections vanish when you produce a coherent account of the issue at hand, and in the end nothing really changes for how we should behave or what attitude we should embrace. Clark misses this conclusion by trying too hard to show how things change when we abandon popular superstitions about free will, when in reality anyone who takes a rational position on any issue in the first place will find that it doesn't matter what you think of free will. For example, purely retributive justice is demonstrably immoral regardless of whether we have supernatural free will, and is not rationally supportable even if we did. That's a far more important conclusion. You will understand a lot more about the world, when you understand that.
Accordingly, as naturalists Clark and I occasionally come to different conclusions about what attitudes and behaviors are warranted in various contexts. I think he hangs far too much on his premises about free will, and in consequence I believe some of his conclusions are naively dangerous. For example, on page 65 he suggests a disbelief in supernatural free will warrants politically suppressing free trade and free speech, to create a world in which the government decides what we can see, hear, or have access to, in order to "protect" us from ourselves. That is a doomed project that gives far too much power to the state, power that (as the empirical facts of history and human psychology demonstrate) will never be used with enough uniform justice to ever be a good idea. A better plan (which Clark also supports) is to promote an education system that teaches people as individuals to make informed, critical, self-reflective decisions, so they can't be so easily manipulated by advertising or propaganda in the first place. That gives power back where it belongs: to the people themselves, not some nebulous cabal of black hats in D.C. (or wherever). Again, a culture of individual responsibility causes people to take charge of their own lives, as they are perfectly capable of doing, if educated with the appropriate skills and experience. The result will always be a better world, with power more decentralized, and people making better decisions in every aspect of their lives.
Nevertheless, despite the disagreements I have enumerated, we far more often agree, and Clark often says things well, and covers angles and subjects I only skim in my book. His entire approach of applied naturalism is one well worth adding to your life and library. At the very least, Encountering Naturalism makes a good starting point for thoughts and discussions about the implications of naturalism and how as a worldview it can improve our decisions and behavior, and our society and government as a whole. Because even when you disagree with him, the effort this will motivate (to identify where either he or you have gone wrong in your thinking, and what the facts establish is correct) will be of considerable use to every naturalist thinker. And to that end I recommend Clark's very affordable book.
For a follow-up essay on Clark's naturalism, in which I respond to his critique of my review here, see Does Free Will Matter?