Natural theology can be defined as:
the attempt to provide rational justification for theism using only those sources of information accessible to all inquirers, namely, the data of empirical experience and the dictates of human reason. In other words, it is defense of theism without recourse to purported special revelation.2The book begins by laying out David Hume’s criticisms of natural theology. Hume’s criticisms against miracles and natural theology are evaluated thoroughly and honestly. Todd M. Furman contributes a chapter In Praise of Hume that brings to light what Hume got right in his critiques. This includes three categories of mistakes that “eager-believers” make when doing natural theology.
In one of the most notable chapters in the book, James F. Sennett introduces what he calls “Hume’s stopper,” which is the common objection that even if arguments from natural theology are successful, they don’t prove the Christian God: “In short, Hume’s stopper is the accusation that any natural theology argument, even if sound, simply does not prove enough.”3
Sennett also exposes what he calls the “ignorance assumption,” which asserts that “we must, in assessing the conclusion of an argument, presume ignorance of any information not available to us via the premises.”4 He shows how the use of this assumption is necessary in assessing the logical value of an argument, but seems to fail when the goal is an overall search for truth. He distinguishes between logical evaluation of an argument and alethic evaluation of an argument. (Alethic meaning having to do with the discovery of truth): “An argument may fail as a piece of pure logical defense of its conclusion, while nonetheless spurring us forward by great leaps toward discovering whether or not its conclusion is in fact true.”5
In other words, the ignorance assumption is only applicable to the logical evaluation of an argument. In a search for truth, it is appropriate to incorporate knowledge outside the scope of the particular argument in assessing its value. This is what Sennett refers to as “facts not in evidence.” Sennett also presents a “candidate gods” approach to see which candidate best fits the extended form of the argument using the “facts not in evidence.” He explains:
However, when our quest is for truth, we are permitted – even required – to look beyond the confines of the argument at hand to ask what broader reasons there are to choose among the candidates. Armed with this panoramic perspective, the choice between the God of theism and the gods of slapstick is a philosophical no-brainer.6This seems to be a helpful insight, and this chapter alone is worth the price of the book. Sennett also goes on to defend his case against a number of objections.
Moving through the book, Douglas Groothuis contributes a chapter detailing the metaphysical implications of cosmological arguments. After describing various versions, he shows just how much each can and cannot prove. This chapter is followed by Garrett DeWeese and Joshua Rasmussen’s detailed statement and defense of the kalam cosmological argument.
James D. Madden then compares classical teleological (design) arguments with modern versions and shows how the modern teleological arguments are not subject to some of the criticisms of design arguments from two centuries ago. Some of the sharper criticisms against design are described and answered. On the heels of the design argument comes Robin Collins’ defense of fine-tuning arguments. He also deals with the common “Who designed God?” objection. As is notable throughout the book, here Collins again draws the line on exactly what this particular argument proves and what it does not prove.
Paul Copan defends the moral argument against Hume’s criticisms, while presenting five main areas of contention with Hume. Victor Reppert defends the argument from reason in light of Hume’s “legacy” and makes a case that naturalistic worldviews fall short in accounting for reason. Probably the deepest chapter of the book is by J.P. Moreland as he defends the argument from consciousness: how can mere matter originate consciousness?
Douglas Geivett concludes the book with a cumulative case for the existence of God. Geivett also points to what he sees as Hume’s key mistake:
Hume’s critique of theism is piecemeal. Like so many other opponents of theism, he tends to isolate individual evidential components in the case for theism, impose an inordinate evidential burden on each component, and then conclude that each component withers under such searching scrutiny.7Geivett emphasizes that a cumulative case is stronger if it is made for Christian theism than if it were made merely for a generic theism, and he shows why as he presents his outline for a cumulative case for Christianity. This includes: cosmological evidence, design evidence, the human condition, the need for revelation, the arena of religious traditions, the evidence of miracles, making the truth believable, and religious experience.
In conclusion, In Defense of Natural Theological is a very valuable work that is sure to be a useful resource for the student of natural theology. Keith Yandell sums up the book nicely:
The idea that Hume dealt a deathblow to natural theology is sheer fiction. The degree to which natural theology succeeds is the degree to which its arguments are valid, have true premises and are persuasive to the auditors. Hume's critique does not show what that degree is – it will have to be decided on its own merits.81 James F. Sennett & Douglas Groothuis, In Defense of Natural Theology: A Post-Humean Assessment (Downers Grove, IL: InterVarsity Press, 2005), p. 15.
2 Ibid., p. 10.
3 Ibid., p. 82.
4 Ibid., p. 87.
5 Ibid., p. 88.
6 Ibid., p. 97.
7 Ibid., p. 299.
8 Ibid., p. 81.