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God And The Challenge of Skepticism

Summary: Most atheists have argued that in order for the Christian to prove that God is real, he must also prove that alternative theories are false. But is this sound? In this article, apologist, Ben Fischer, reveals that such arguments have been shown by modern philosophy to be baseless. To sign up for future updates, click here.

Questioning Skepticism

In his celebrated book, Philosophical Explanations, American philosopher, Robert Nozick, wrote the following: “What is philosophically interesting, what demarcates … important disagreements … is the domestic problem presented for our own beliefs.” (Nozick, 1981, 18)

Robert Nozick was a controversial figure. He believed his professional work resolved the ancient problem of skepticism. His various special interests covered a wide variety of topics, and included such ethereal subjects as modern utopian theory. His approach to technical writing was generally known for its ecumenical tone and non-aggressive demeanor. Today, Robert Nozick is most widely remembered for his famous theory of knowledge which built him his reputation.

“[T]o attempt to explain how knowledge … can be known,” wrote Nozick, “is a task of my belief [system].” (Nozick, 1981, 16) “How is it possible that we know anything, given the facts [that] the skeptic enumerates.” (Nozick, 1981, 8) Continuing, Nozick wrote: “the … problem of skepticism … has been presented as the problem of refuting the skeptic … of proving to him that you … know what he denies you know.” (Nozick, 1981, 15)

From here, Nozick formulated his controversial position.

Presently, Novizk’s views are widely debated. Philosophers, by-in-large, seem to disagree with his assessments. If skepticism has been refuted, then it would seem that religious dissenters have lost one of the principal weapons in their defenses. But more than that, Nozick’s sweeping refutation would affect drastic change in our understanding of knowledge and reason. For this cause, scholarly interest has continued to rage around the subject of Robert Nozick’s broader philosophical challenges.

The principle question is this: Do the arguments work? Have they succeeded in accomplishing their objectives? Or, to put it more precisely: Has the late Robert Nozick somehow discovered the key to vanquishing philosophical skepticism?

Popularly speaking, skepticism has been understood as an indispensable tool for motivating scientific research. But is it possible that this idea is simply wrong, and that skepticism has been defeated, leaving its proponents without justification?

Encountering Skepticism

Prior to writing this article, I wrestled with these questions. I was asked to appear on an atheist youtube program. The request had come from an emerging atheist philosopher who had debated numerous Christian intellectuals in hopes of defeating theism. Reluctantly, I agreed, knowing that the show would be aired live, leaving me with no ability to edit my responses. I therefore somewhat nervously accepted the invitation and sat before my computer, quietly awaiting my inquisition.

“I am an atheist,” my interviewer began, “by which I mean that there are no good arguments for God’s existence. Using any argument you believe proves God, I can craft a parallel case for belief in modified pantheism. Therefore,” he continued, “since you cannot disprove any of my model arguments for pantheism, then you cannot succeed in proving God’s existence. How then can you claim rational belief in Christian theism?” The question rang out as he concluded his opening comments.

Pausing, I briefly considered my opponents question. Immediately, I could see that this was not a defense of atheism. In fact, nothing about the substance of the challenge logically justified the claim that God does not exist. After all, we might conjecture, it may be true that God is real, despite our inability to refute alternative theories. What therefore was this question seeking to accomplish? It did not appear that the man’s argument justified his position.

I therefore perceived that my opponent had redefined his terms. He had assumed a nontraditional definition for textbook atheism. For the Stanford Encyclopedia of Philosophy states: “atheism should be construed as the proposition that God does not exist.” (Draper, 2017) Conversely, the argument which I was now hearing was merely an attempt to somehow show that it is impossible to be certain that God exists. Strictly speaking, this is quite different from the types of arguments we are normally accustomed to hearing from more traditional forms of atheism.

Seeing so, I therefore turned to the main issue—namely; my opponents misguided use of skeptical reasoning. For the trouble with such cases is that the argument of skepticism, correctly understood, actually explodes atheistic belief. This is due entirely to skepticism’s central claim which denies our ability to attain to knowledge, defined as certainty. The problem is that this is precisely what atheism is claiming—namely; the knowledge that God does not exist.

Turning to the argument, we thus see the problem immediately: If I know that theism is true, then I know that pantheism isn’t. According to my opponent, since we cannot disprove pantheism, then we cannot be certain that God exists either. The problem is that the argument seems to work equally as well when we choose to point it in the opposite direction: If I know that atheism is true, then I know that theism isn’t—since I can’t disprove God, I cannot be certain he does not exist.

This would be the problem with classical skeptical reasoning. The argument seems to render all knowledge as technically uncertain. For in the case of any two opposite propositions, skepticism holds that we are brought to a philosophical stalemate. For this reason, skepticism is a poor defense of atheism, since it denies the very thing which the atheist is claiming. For it holds that no propositional theory can ultimately be justified, a point which if accepted, would force the atheist to plead agnosticism.

Unfortunately, my opponent seemed blissfully unaware of this problem. Instead he continued to contend for his belief in God’s inexistence. Using the skeptical argument, he forcefully held that his views were all but successful in debunking Christian theism. Admittedly, the contentions of skepticism are quite powerful, as seen by their ability, at times, to lead even Christians to unbelief. The question is, do they inevitably succeed, even in the face of modern (secular) objections against them?

Responding to such a question will require a brief intro to skepticism. The most primitive examples date back to the third century (BC). Here, early inquirers were severely sore-perplexed with their inability to relegate matters of doubt and uncertainty. Modern thinkers later described the problem as hinging upon a concept known today as the principle of deductive closure. The challenge seems to be that the very practice of human inquiry makes human knowledge impossible to effectuate.

This problem eventually gave rise to a new breed of arguments, which all sought novel approaches to resolving skeptical reasoning. The most famous examples would be those of Robert Nozick, who argued that the challenge of skepticism is solved if we redefine knowledge entirely. Thus a new definition (or so it was believed) could plausibly force the skeptic to admit to his defeat. But what sort of argument could solicit such a response?

To answer, we will need to survey the history behind Nozick’s reasoning.

The Battle For Knowledge

In 1963, American philosopher, Edmund Gettier, published a brief paper on the subject of true belief. (Gettier 1963) Using a set of counter-examples, Gettier demonstrated that our classical definition of knowledge was ostensibly incomplete. This in turn had the effect of weakening the skeptic’s argument—a point which becomes all-too-easy for us to see. For what good is the skeptic’s claim that knowledge is impossible if, in the end, we can’t even agree on precisely what knowledge is?

Edmund Gettier’s paper may as well have been a smartbomb. Nozick himself later bemoaned the effects of its awful sting. “Early in the flurry of journal articles,” he reflected, “I despaired of anyone’s getting it … right [and] I stopped reading that literature.” (Nozick 1981, 169) Later, Nozick realized after responding to Gettier’s challenge that his solution bore relevance to the problem of skeptical reasoning. He therefore concluded that his ability to beat skepticism was a sure sign that he had somehow managed to define knowledge correctly.

Here was his argument:

Using a set of four important criteria, Nozick held that knowledge could be defined counterfactually. In a plain sense, this meant that knowledge could be known, so long as the inquirer was willing to agree to certain conditions. Notable among them were his third and fourth criteria which are roughly represented in the following pair of statements: (Nozick 1981, 172–187)

  1. if a proposition is true, then person S would believe it;

  2. if a proposition is false, then person S would deny it.

To the untrained, the above two conditions seem innocuous. If something is false or true, shouldn’t that reasonably shape our beliefs? Controversy, however, again began to arise as modern scholars grasped what Nozick was subtly declaiming. If the main conclusion of skepticism, that knowledge is impossible, were somehow undermined, then the argument would be defeated. Nozick’s definition now seemed to carry that very effect. His two criteria appeared to have bested skepticism completely.

Perhaps the easiest way to illustrate Nozick’s argument would be through the following model case: Person S believes that God exists. According to Robert Nozick, the skeptic is constrained to argue that even if God existed, person S’s belief as such would not count as knowledge. Instead, person S would need to be willing to become an atheist if it turned out, after all, that God did not exist. Thus, person S could only claim the knowledge of God’s existence if:

  1. He would believe in God if he existed, and

  2. He would deny him if he didn’t.

On the basis of these two conditions, it is easy to see why skepticism fails. For the main dispute of skepticism is dependent on radically different reasoning. The argument classically holds that for all paired opposing claims, if person S knows one is true, he also knows the other is false. But Nozick’s new argument now created odd exceptions to the belief that affirming (P) and denying (Q) will always lead us to knowledge. Instead, Nozick demonstrated that this belief was found to be false such that there was no longer any reason to be detained by the skeptic’s clamorings!

To construe the problem plainly, consider the theory's most vivid example—namely; the now infamous brain-in-the-vat argument. Suppose the machine had instilled in its subject the awareness of his envatted state. According to Robert Nozick, this would fail to count as knowledge. For regardless of the fact that the machine was telling the truth, the subject would never have guessed it if the computer hadn’t told him. Thus even though his awareness was adherent to the facts, it wasn’t due to his sensing it so, and so therefore—wasn’t knowledge.

What is perhaps most startling is that Nozick’s argument works specifically because the subject can now draw the broader conclusions. For the subject may now correctly deduce (on the basis of his envatted condition) that the real world lies utterly beyond his present empirical borders. So concluded Nozick, the skeptic’s appeal (if P, ~Q) is not some sort of a prerequisite for attaining unto knowledge. Instead, knowledge is something which human beings intuitively construct by relying upon conditions similar to Nozick’s twin requirements.

This had the effect of utterly imploding skeptical reasoning! For the skeptic demands we falsify all opposing (theological) claims. But this is precisely the thing which Nozick’s argument was inveighing—namely; the belief that confuting Q is necessary for knowing that P. Hence, whatever else the skeptic was denying, it certainly wasn’t knowledge, since the skeptic’s argument was now found to be based on faulty conditions! Therefore, the only outstanding question is, was Robert Nozick right? Was his famous reply to Gettier also a defeat for classical skepticism?

There are several good reasons for thinking that it wasn’t. The chief one is that Nozick himself suspected his reasoning was wrong. To see why, try imagining the following set of conditions in which truth and proof would fail to properly lead you to knowledge: (1) your son is innocent, and (2) you have the proof. In case you love your son, said Nozick, you cannot “know” of his innocence. The reason is that if he had been guilty, you would still deny it, since your belief is formed, not just by the evidence, but by your love for the accused under question.

On purely intuitive grounds, there is obviously something wrong with this. If your son is truly innocent, then nothing should prevent you from rationally claiming it. Yet for the very same reason, it seems that we need to also admit that a similar scenario should not prevent us from claiming rational theism. If: (1) God does exist, and (2) we have the proof, the Christian should be amply justified in claiming this as knowledge. Most notably, this would be true whether or not the believer is willing to give up his faith in God in case that God does not exist.

Thus, in a surprising sense, Nozik’s argument was itself, poorly conceived. Consequently, his seminal thinking was never generally accepted. At the same time, there is an important lesson left behind for us here, which, if sound, would easily defeat the skeptic’s main contentions. It will therefore be my goal to review that lesson here, and to show why skepticism, despite its appeal, nevertheless fails to succeed. For what follows I am indebted to the work of philosopher, Peter Klein.

Let's conclude.

Refuting Skepticism

Since its inception centuries ago, skepticism has taken several forms. All of them have consistently claimed to be utterly irresolvable. But there is one dominant shape which has commanded the greatest attention, and which is comprised of three key premises as we see them captured below:

  1. If I know that P is true, I also know that Q is false.

  2. I cannot know that Q is false.

  3. Therefore, I cannot know that P.

Unquestionably, this is the skeptic’s main defense. It has become a core argument for protecting atheist beliefs. For this reason, the man defending doubt from the case for God’s existence usually formulates his argument in a very predictable way. He begins by letting “P” signify any Christian belief, and then claims that “Q” is some sort of plausible contradiction. Finally, he concludes by arguing that since we cannot disprove Q, we cannot know for certain of the truth concerning P.

It is important that we understand the argument here correctly: The skeptic is claiming it is impossible to know that Q is wrong. In other words, there is some sort of in-principle reason why the falsity of Q can never be known to us. Example: Sir Antony Flew said theology was unfalsifiable. Assuming this is correct, no religion can be disproven. The skeptic therefore defends his atheism on the familiar grounds that since we cannot falsify Q, we cannot know for certain that P.

But the problem with the skeptic’s argument has now become detectable. Return for a moment to what we saw in our previous discussion. On account of the fact that God is wholly immaterial, the skeptic claims it is idle for us to speak of “proof” for God’s existence. But must God be material for us to know that he exists? If the skeptic answers “yes,” he has dismantled his own objection. For he has contended that S’s awareness of God must be due to his sensing it so—the very criterion which Nozick showed would dismantle the skeptic’s objection.

Hence ironically, it does not seem to matter whether Nozick’s definition is right. His argument against the skeptic's views nevertheless stands. For recall that the envatted person could affirm that P as well as deny that Q, yet oddly, be unable to “know” the truth of his own condition. The reason, as we noted, is that Nozick made “knowing” P partially contingent upon personally “sensing” that P. It is clear that the atheist has argued in precisely this manner. He has therefore contradicted the basis for his own reasoning.

It is difficult to imagine a rebuttal to faith which would somehow be untouched by this. Virtually every argument against God is related to this sort of thinking. Hence Richard Dawkins comically compares belief in God’s existence to belief in a wholly invisible flying spaghetti monster! But S’s failure to disprove the spaghetti monster through the use of his senses is no proof that he cannot be certain of God's existence. Such comparisons are frankly embarrassing for the atheist who fashions them because they rely on arguments which are now philosophically dated.

Incidentally, the same is true for numerous other skeptical arguments. Why, for example, believe that Christianity is the only right religion? Since we cannot know by sensory proof that Hinduism is false, we cannot really be sure of the truth of the Christian religion. But once again, such arguments are reliant upon claims which have been philosophically defeated since the early 1980’s. It is therefore high time for modern atheism to come of age. There is simply no longer any refuge for the theory to be found within ancient skepticism.

This month, may you be filled with hope as you seek to defend your faith in God's existence.

Veritas Curit.



  • Robert Nozick, Philosophical Explanations (Harvard University Press, Massachusetts, 1981).


  • Gettier, E., 1963, “Is Justified True Belief Knowledge?” Analysis, 23: 121–123.




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