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Zens' Defense of TAG (2000)

Michael Martin


In a recent internet paper entitled "A Christian Response to atheist thinker, Michael Martin on TAG and the foundation of induction," Adam Spurgeon Zens attempts to defend Greg Bahnsen's inductive form of the Transcendental Argument for the Existence of God (TAG).[1] Unfortunately, Zens does not seem to understand the challenges to inductive skepticism that I cited in my paper "Does Induction Presume the Existence Of The Christian God? (DIPCG)," and completely ignores my argument there that Christian theism does not answer the inductive skeptic.[2] Indeed, Zens simply assumes without argument that belief in God provides a justification of induction. As a result he provides no defense of Bahnsen's inductive form of TAG.

TAG and Induction

As I showed in DIPCG, there are two parts to Bahnsen's inductive form of TAG. First, there is an assumption that, without God, induction is a philosophical problem and because of this problem we are reduced to accepting inductive skepticism. In his lectures Bahnsen appealed to the arguments of inductive skeptics such as Hume and Russell to establish this thesis. Second, Bahnsen argued that with the assumption of the Christian God this problem is solved. To establish this thesis he appeals to two things: to Scripture that in his opinion justifies belief in the uniformity of nature, and to God's desire to have His creatures learn --which Bahnsen assumed would not be possible without induction.

In DIPCG, I argued that both parts of Bahnsen's argument are questionable. First, I showed that there have been many arguments against inductive skepticism in the philosophical literature: ones that question whether there is a problem of induction, ones that attempt to show that the problem is incoherent, ones that attempt to show that the problem can be attenuated and solved trivially, ones that maintain that inductive procedures can be vindicated but not justified. In DIPCG I did not endorse these or other anti-skeptical arguments (as Zens seems to imply). Rather I only maintained that they must be refuted in order to establish TAG and that Bahnsen, who seemed unaware of them, made no attempt to answer them. Second, I argued in my paper that Bahnsen's appeal to Scripture solves nothing, and that God's desire for human learning is compatible with inductive skepticism.

In order to answer my argument Zens must show that the critiques of the inductive skepticism of Hume and Russell which I cite can be refuted. In other words, he must show that the various attempts to dissolve, undermine, or by-pass inductive skepticism are unsuccessful. He cannot simply assume they are unsuccessful without begging the question. The difficulty of this task cannot be exaggerated for it involves refuting the complex and subtle philosophical arguments that appear in dozens of books, and philosophical articles, and papers. In addition, Zens must refute my critique of Bahnsen's two arguments. Again, he cannot simply assume my critique is wrong. He must show it to be.

Zens' Formulation of TAG

Zens provides what he believes is a "lucid statement" of TAG:

1. We learn inductively about a given system of behaviors (whether natural or artificial) by gathering information within a cause-and-effect schema and projecting our schema-based understanding onto the future events.
2. But this projection of causal structure onto the future is logically or theoretically unwarranted apart from a faith (or faith-like belief) that the future causally will proceed in the same or like manner as a present systems of behavior. (Here Bahnsen cites philosophers who've shown the unwarrantness of this belief, such as Hume).
3. The God of Scripture gives the best account of why future events behave in a way which is amenable to present induction and the articulation of inductively oriented laws which give us a good idea of how a system will behave in the future.
4. Thus, God needs to be presupposed to explain the regularity of future causality which proceeds in accordance with past or present causality.

Given this formulation, in Premise 2 Zens must defend inductive skepticism against the many criticisms against it. In Premise 3 he must meet my challenge to the two arguments that Bahnsen used to establish 3. However, Zens does not accomplish the first task successfully and does not appear even see the need to attempt the second.

Zens' Defense of Premise 2

Does Zens refute the many critiques of inductive skepticism found in the philosophical literature? Not at all. To take just one example, in DIPCG I cite the approach taken by philosophers such as Hans Reichenbach that the practice of basing one's action on inductive arguments can be pragmatically vindicated. On this view, if there are any true inductive generalizations, the consistent use of induction will discover them in the long run.[3] To be sure, this approach does not justify induction, but it does provide a practical reason for continuing to use this mode of reasoning. From Zens' response which is to bring up a pragmatic justification of Hitler's immoral medical practice, it seems that he has not fully grasped Reichenbach's position. Most of the other anti-skeptical approaches I cite he does not even mention.

Zens' Non-Defense of Premise Three

The crucial issue for Premise 3 is how it is to be established. Bahnsen tried to provide arguments for it, but in DIPCG I showed that these were unsound and that inductive skepticism is compatible with belief in God. Rather than answer my challenge Zens argues that there is no need to do so. He says:

The real issue is not whether Christianity can answer these sceptics. It has no need to. It understands that God works His will through whatever means He sees fit in accordance with the beauty and convenantal faithfulness of his character. . . God is the creator of the environment in which "physics" takes place and He discloses principles of regularity which obtain within the environment according to His good pleasure.

This statement begs the question and also demonstrates the need to answer the inductive skeptics. Since, as Zens says, God can work His will in whatever way He sees fit, He does not have to use the uniformity of nature. God can accomplish His goals without it and may have chosen to do so. Why then believe that nature is uniform if God exists? Although in DIPCG I expand on this idea, Zens ignores my arguments.

Zens' Confusion of Materialism and Atheism

Throughout Zens' defense of Bahnsen he commits the same error that Bahnsen himself made by systematically confusing atheism with materialism. Again and again Zens refers to atheists as materialists, yet not all atheists are materialists. Materialists believe that everything is composed of matter. Some atheists, however, have doubts about whether abstract objects such as numbers and mental events such as thoughts are material. What is so surprising about Zens' confusion is that I pointed it out in a 1996 internet paper that Zens links to his own paper.[4]

This confusion between atheism and materialism adversely affects Zens' argument in the last part of his paper. There he maintains that a materialist is committed to methodological solipsism. But whether correct or not, this point is irrelevant to my defense of atheism and my critique of TAG.


To his credit, Zens has chosen to devote a web page to a defense of TAG and a critique of my paper. However, both his defense and his critique are woefully inadequate in that they either ignore my arguments or miscontrue them.


[1] Adam Spurgeon Zens, "A Christian Response to atheist thinker, Michael Martin, on TAG and the foundation of induction" (<URL:>, 1999), spotted January 9, 2000.

[2] Michael Martin, "Does Induction Presume the Existence Of The Christian God?" Skeptic Vol. 5, #2, pp. 71-75 and republished at <URL:>, spotted January 9, 2000.

[3] For this approach see the selection from Reichenbach in M. Foster and M. Martin (ed.), Probability, Confirmation and Simplicity, pp. 423-34.

[4] Michael Martin, "Reply to Bulter, Ventrella, and Fields," (<URL:>, 1996) spotted January 9, 2000.