Naturalism and Religion

A Contemporary Philosophical Investigation

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Graham Oppy
Investigating the Philosophy of Religion
  • New York, NY: 
    , May
     206 pages.
     For other formats: Link to Publisher's Website.


Arguably Australia’s leading philosopher of religion, Graham Oppy is known for writing meticulous and compendious treatises such as Ontological Arguments and Belief in God (Cambridge University Press, 1995) and Arguing about Gods (Cambridge University Press, 2006) as well as for editing a series of similarly meticulous and compendious reference works such as The History of Western Philosophy of Religion (coedited with Nick Trakakis; five volumes; Oxford University Press, 2009). These are books produced by a professional philosopher for a readership of professional philosophers. Recently, however, Oppy’s output is increasingly addressed also to a broader audience, with such works as Reinventing Philosophy of Religion (Palgrave Pivot, 2014), Atheism and Agnosticism (Cambridge University Press, 2018), and Atheism: The Basics (Routledge, 2018).

Naturalism and Religion falls in the latter category, published as it is in a Routledge series aimed at “students, scholars, and all those who want a fairly detailed but concise overview of the central issues in contemporary philosophy of religion from the perspective of the major world religions.” Oppy in fact insists that naturalism—which he carefully defines as the conjunction “(1) there are none but natural causal entities with none but natural causal powers; and (2) scientific method is the touchstone for identifying natural causal entities and natural causal powers” (25)—is not a religion, since religions, on his view, are committed to the existence of non-natural causal entities and/or powers. But otherwise the book is in harmony with the aim of the series. And indeed it succeeds splendidly at delineating the philosophy of religion as seen from the viewpoint of naturalism.

Oppy’s methodology is refreshing. As he observes, it is common for naturalism’s opponents to criticize particular versions of naturalism for their supposed explanatory failures without considering whether the criticisms apply to naturalism as such or whether their preferred views (such as theism) are explanatorily successful. Instead, he recommends that “we develop all the big pictures in which we are interested with the same level of care to the same level of detail, and then we make an objective comparative assessment of their theoretical virtues relative to all the available evidence. Among the big pictures that we are assessing, the best are those that do best in balancing the full range of theoretical virtues given all of the available evidence” (3). At the end of the day, his conclusion (offered in chapter 8) is that naturalistic big pictures are the best.

On the way to that conclusion, Oppy covers a lot of ground. Chapter 1 introduces the project and describes the plan of the book; chapter 2 defines naturalism in the minimal way quoted above, which intentionally leaves plenty of issues on which naturalists can—and do—disagree; and chapter 3 defines religion in a way indebted to the anthropologist Scott Atran. Particularly important for Oppy’s project is the requirement that religions are committed to the existence of the non-natural, ensuring the opposition of naturalistic and religious big pictures and also enabling the rejection of the claims that naturalism, philosophy, and science are themselves religious. These definitions of naturalism and religion are further deployed in chapter 4, in which Oppy considers—and ultimately rejects—the possibility of naturalistic religions: nothing is appropriately so described.

It is in chapter 5 that the book turns from the definitional to the argumentative, with a discussion of Alvin Plantinga’s famous—or infamous—argument that science (and in particular evolution) defeats naturalism, as found in his Where the Conflict Really Lies (Oxford University Press, 2011). Following in chapter 6 is a discussion of Michael Rea’s argument, as found in his World Without Design (Oxford University Press, 2002), that it is impossible to formulate a substantive philosophical position (as opposed to a mere “research program”) of naturalism, as well as a discussion of “a more generic challenge provided by contemporary Thomism” (86). Puzzlingly, however, no contemporary Thomists are cited in the latter discussion: only the Angelic Doctor himself is mentioned. These discussions are uniformly intricate, careful, and rewarding. 

Equally rewarding, and certainly of wider interest to a general readership, is Oppy’s nuanced and informed discussion, in chapter 7, of whether science defeats religion. After defining science and debunking the claim that science is itself a religion, he reviews the survey data on religious belief among scientists, emphasizing that “there have been, and are, scientists distributed all the way across the spectrum of religiosity” (138), and argues that there are no scientific findings that suggest any decisive reason for religion to be abandoned. In terms of Ian Barbour’s familiar typology of science–religion interactions, he sees no prospect for a dialogue between or integration of science and religion, while holding that it is going to be the details of a particular religion—not religion in general—that determines whether independence from or conflict with science is the result. 

Finally, in chapter 8, Oppy offers his argument for naturalism. Briefly, he argues that the best naturalist big pictures are both minimal and maximal as compared to their competitors—that is, encumbered with fewer commitments and endowed with as much explanatory power. The minimality thesis is relatively uncontroversial, since it is generally accepted that there are natural causal entities; the question is whether there is reason to believe in anything further. The bulk of the chapter is thus devoted to reviewing, at a breakneck pace, a host of traditional arguments in the philosophy of religion, here construed as arguments against the explanatory power of naturalism. Oppy is modest about his ambition here: while he finds it compelling, he writes, “I do not claim that anyone who fails to be persuaded by this case is irrational” (184). 

There is certainly room for argument with Oppy’s conclusion and with the considerations on which it depends; it is to his credit that he acknowledges as much. One reservation about the overall approach he seems not to have anticipated, however: Oppy conceives of philosophy—or at any rate the part of the discipline in which he is interested here—as in the business of offering explanations. And he conceives of such explanations as similar to scientific explanations, citing the same panoply of theoretical virtues that a philosopher of science would cite. But it is not tremendously surprising that a philosophical methodology modeled on science turns out to certify a big picture that endorses science as the ultimate arbiter of reality! Oppy’s approach is not circular, but it invites—in a way that he would surely welcome—further exploration of the nature of philosophy itself.

About the Reviewer(s): 

Glenn Branch is Deputy Director of the National Centre for Science Education.

Date of Review: 
September 12, 2018
About the Author(s)/Editor(s)/Translator(s): 

Graham Oppy is Professor of Philosophy in the School of Philosophical, Historical and International Studies at Monash University, Australia.


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