Skepticism Is Not Worthy of Belief

Jason Dulle

J.P. Moreland said the quest for knowledge requires that we maximize our true beliefs and avoid false beliefs. Most people keep a balanced perspective on this quest, but every once in a while you will meet the radical skeptic. He's the guy who thinks avoiding error is more important than obtaining truth. For every claim to knowledge you make he will respond with "How do you know that?" Whatever your justification may be the skeptic will again ask, "How do you know that?"

Radical skeptics doubt virtually everything. The only thing skeptics fail to doubt is doubt itself. To be consistent, however, the skeptic should be skeptical of his own skepticism, but he is not. The skeptic claims to know we cannot claim to know anything, which is itself a claim to know something, and thus eminently self-refuting.

In addition to being self-refuting, skepticism as a general philosophy of knowing is also irrational and impractical. It is irrational because it is epistemically impossible to doubt all things. Doubt rests on beliefs that are themselves not doubted; i.e. doubt requires prior knowledge.1 As Philip Johnson wrote, "One who claims to be a skeptic of one set of beliefs is actually a true believer in another set of beliefs." Doubt arises only when some claim to knowledge conflicts with something we already believe we know to be true. For example, we doubt a particular experience because we know we have been misled in the past.

This is problematic for the skeptic because his worldview denies that anyone can have such knowledge. To admit knowledge of anything gives up the skeptical farm. To make matters worse, not only does the skeptic have to justify how he knows those beliefs are true, but also how he knows those beliefs that justify the original beliefs are true, ad infinitum. So not only does he have to justify his claim to know one thing, but an infinity of things!

While it is natural to the learning process to doubt some truth-claims (modest skepticism), it is not possible to doubt all truth-claims (philosophical skepticism). Modest skepticism is natural and healthy,2 but full-blown philosophical skepticism is a dead-end street. Doubt presupposes knowledge, and knowledge requires some level of faith.

Skeptics think that unless there is no room to doubt X, there is no warrant for thinking you know X.  This is both fallacious and impractical. While we could be mistaken in what we believe we know to be true, we need not be mistaken, and should not doubt that what we think we know we actually do know unless we have good reason to doubt it. The mere possibility of being mistaken does not make it likely that we are mistaken, or give us reason to believe we are mistaken.3

David Hume argued against skepticism by pointing out that it was a vicious cycle of irrationality. William Lane Craig and J.P. Moreland summarized his argument as follows:

We start by trusting our reason. But, later, we encounter skeptical arguments against that trust and so we stop trusting reason. But once we do this, we no longer have any reason to accept the skeptical arguments themselves and continue our mistrust of reason. At this point, I begin to trust reason again, but then, the skeptical arguments reassert themselves and so forth. We have entered a vicious dialectical loop that, eventually, will reach a sort of intellectual paralysis.4

Skepticism is also impractical because no one can live out their skepticism in the real world. While a skeptic may profess that he does not know whether he and the train exist, he will not test/demonstrate his skepticism by standing in front of the moving train. Reality has a way of converting such radical skeptics, but they typically don't live long enough to write books about it!

In summary, the only sufficient reason for doubting something is because we already know something else. And if we have to know one thing to doubt another, then skepticism as an epistemological theory is falsified. Likewise, if skeptics are not willing to allow their skepticism to alter how they behave in the world, then skepticism as an epistemological theory is practically useless.


J.P. Moreland suggests a couple of tactics to deal with the skeptic. Both come in the form of a question.

First, ask the skeptic why he thinks you have to know how you know before you can know something. If he does not know why he thinks this, or does not know how he knows it to be true, then why should you doubt what you think you know? If he does know why, ask him how he knows it!

Secondly, when the skeptic asserts that we cannot know anything ask him, "Do you know that we cannot know anything?" He might respond, "No, I just think we cannot know anything at all." To that reply, "Do you know that you think we cannot know anything at all, or do you just think you know we cannot know anything at all?" He will realize that he is being led into an infinite regress he cannot escape from. He will have to admit at some point that he really does believe he knows something.


Related articles:

How to be a Good Agnostic


1. Rick Wade, "Confident Belief: What Does It Mean to Know Truth?"; available from; Internet; accessed 13 April 2005.
2. This form of skepticism is called "methodological skepticism." The use of doubt is taken as a guiding principle to better understand and justify knowledge. The difference between methodological skepticism and iterative skepticism is that the goal of the former is the attainment of knowledge, whereas the goal of the latter is perpetual doubt. We must distinguish, then, between "doubt as a method and doubt as a habitual character trait. … If doubt, understood as a character trait, helps one avoid naiveté, then it is an intellectual virtue. If it produces cynicism and a loss of faith, then it is an intellectual vice." (J.P. Moreland and William Lane Craig, Philosophical Foundations for a Christian Worldview (Downers Grove, IL: InterVarsity Press, 2003), 94.
3. J.P. Moreland, "Answering the Skeptic"; available from; Internet; accessed 28 March 2005.
4. J.P. Moreland and William Lane Craig, Philosophical Foundations for a Christian Worldview (Downers Grove, IL: InterVarsity Press, 2003), 107-8.

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