In this book, Encountering Naturalism: A Worldview and Its Uses, Thomas Clark, founder and director of the Center for Naturalism, provides a superb introduction to the worldview known as Naturalism, as contrasted with the supernatural worldview shared by most of the world's religions. The work is not intended as a philosophical or scientific defense of Naturalism, which can be found elsewhere (e.g., Richard Carrier's book Sense and Goodness Without God), but rather a consideration of the implications of Naturalism for our view of ourselves in relation to the rest of the universe and for the promotion of a compassionate and progressive society. Although Naturalism has been variously defined by different authors, at its core is the view that Nature is all there is, that there are no supernatural realms or entities, such as gods, spirits, and ghosts, and that human beings are fully embodied organisms embedded in the causal network of the universe. Moreover, Naturalists are generally committed to an evidence-based, rationalistic epistemology, as exemplified by the sciences. A key implication of Naturalism as a scientifically-informed worldview is that the mind is entirely dependent upon the operation of the physical brain, which is subject to the same basic physical laws as those governing the behavior of inanimate matter. We are fundamentally material beings whose perceptual and cognitive faculties are products of eons of biological evolution. Consequently, humans do not possess a disembodied soul that survives death; all of our choices and decision making processes are fully caused phenomena.
One of Clark's main themes concerns the implications of Naturalism for the question of free will. On this topic, Clark gives a clear, concise, and convincing presentation. If indeed our choices are fully caused by a combination of genetic and environmental influences, as suggested by our best scientific evidence to date, then we could not have done otherwise, given identical circumstances. Thus, the supernaturalistic concept of contra-causal free will is incoherent. Moreover, as Clark points out, injecting an indeterministic component into our decision making processes (e.g., by invoking quantum mechanical processes in the brain) in an effort to rescue contra-causal free will would not give us the free will we value, since this would simply make our choices random and thus entirely out of our control. In the final chapter of the book, Concerns and Reassurances, Clark persuasively argues that even if our choices are fully determined by circumstances beyond our ultimate control (e.g., we don't choose our genes or environmental influences), we are still to be held proximately responsible for our actions. Indeed, this responsibility follows precisely from the fact that our choices and actions are fully caused and not random. Importantly, Clark notes that determinism does not imply fatalism - the notion that the future outcome will be the same regardless of the choices one makes. On the contrary, because we are embedded in the causal network of the universe, the future course of our lives crucially depends on the choices we make.
Throughout the book, Clark thoughtfully considers the implications of Naturalism for social policy, for instance, concerning retributive justice. If, according to Naturalism, we are fully caused beings that could not have done otherwise given the same circumstances, then retributive punishment is unjustified. We can take neither ultimate credit nor ultimate blame for our actions, as anyone in our shoes would have done exactly the same. However, as Clark notes, this recognition does not by any means preclude the use of rewards and punishments to encourage and deter future actions. On the contrary, carrots and sticks are effective precisely because we are fully caused creatures. Further, understanding the biological and environmental causes of our actions makes us better equipped to shape and control our behavior in the interest of promoting human flourishing. Thus, a naturalistic, scientifically-informed view of ourselves can only lead to a more responsible, compassionate, and progressive society.
As a reviewer, I am obliged also to comment on areas in the book that I feel could have benefited from further clarification. According to Clark, Naturalism is an empirically-based worldview, defined by our best scientific understanding of the world. Naturalism is thus contrasted with supernatural worldviews characteristic of faith-based religions. Thus, Clark comments (p. 64) that science rules out supernatural explanations, since whatever supernatural entities or phenomena science discovers would become integrated into our unified conception of Nature. On the other hand, on the same page Clark states that science does not presume Naturalism- the denial of the supernatural. These statements may appear to some readers as contradictory. However, judging from Clark's other statements in the book and his endorsement of works (such as Dawkins', The God Delusion and Carrier's, Sense and Goodness Without God) that aim at debunking such `supernatural' entities from a scientific perspective, my impression is that Clark would agree that science, at least in principle, can confirm or disconfirm entities or phenomena that are commonly labeled as `supernatural', such as gods, spirits, ghosts, etc. Indeed, on page 4, Clark states that "...the denial of god is just one naturalistic conclusion we reach if we take an evidence-based view of the world". Conversely, in principle science may be able to detect a phenomenon commonly labeled as `supernatural' (e.g., beneficial effects of intercessory prayer), with the possibility of a naturalistic explanation for the phenomenon being highly unlikely (though not impossible). On Clark's view, however, such a discovery would simply render the efficacy of intercessory prayer a `natural' phenomenon. Ultimately, I suspect that this issue may boil down to a matter of labeling or semantics, i.e. how one chooses to define `natural' vs. `supernatural'. Clearly, if all entities or phenomena discovered by science, which might include gods, spirits, or ghosts, are to be defined as `natural', then science does exclude `supernatural' phenomena, but only as a matter of terminology. However, perhaps I have misinterpreted Clark's words here, in which case some further clarification of this point would be helpful, e.g., in a future edition. I unreservedly recommend Clark's book as an exemplary introduction to Naturalism as a worldview having significant implications for the promotion of a rational, compassionate, and progressive society.
Yonatan Fishman, PhD