Regress argument

From Academic Kids

The Regress Argument (also known as The Problem of Criterion and the diallelus) is a problem in epistemology and, in general, a problem in any situation where a statement has to be justified.

According to this argument, any proposition requires a justification. However, any justification itself requires support, since nothing is true “just because”. This means that any proposition whatsoever can be endlessly questioned, like a child who asks "why?" over and over again. Taken at face value, the Regression Argument leads to skepticism.



The argument is usually attributed to Sextus Empiricus, and has been restated by Agrippa as part of what has become known as "Agrippa's Trilemma".

The argument can be seen as a response to the claim in Plato's Theaetetus that knowledge is justified true belief. A skeptic wishes to argue that knowledge was impossible. Whatever argument I may offer to justify some belief, I must offer another in turn to justify my contention that this argument justifies the belief, and then offer another to justify that argument, and so on to infinite regress. It appears, therefore, that it is simply not possible to justify a statement, and that since knowledge is justified true belief, knowledge is impossible.

Formal statement of the argument

Assuming that knowledge is justified true belief:

(1) Suppose that P is some true belief. For it to count as knowledge, it must be justified.

(2) That justification will be another statement – let’s call it P'; so P' justifies P.

(3) But if P' is to be a satisfactory justification for P, then we must know that P' is the case.

(4) But in order to know that P' is the case, it must itself be justified.

(5) That justification will be another statement – let’s call it P"; so P" justifies P'.

(6) We are now back in the same position as in (3), but in this case with P" in place of P'.

This presents us with three possibilities: the sequence never finishes; or some statements do not need justification; or the chain of reasoning loops back on itself.


Perhaps the chain goes on forever. This possibility (called regressism) never provides an adequate justification for any statement in the chain. This would mean that it is not possible to satisfy the criterion for a statement being knowledge — that it be justified true belief. Skepticism would be the only option.


Perhaps the chain begins with a belief that is justified, but which is not justified by another belief. Such beliefs are called basic beliefs. In this solution, which is called foundationalism, all beliefs are justified by basic beliefs. Foundationalism is a form of dogmatism.

Foundationalism is the belief that a chain of justification begins with a belief that is justified, but which is not justified by another belief. Thus, a belief is justified iff:

  1. it is a basic/foundational belief (i.e., it is justified by a non belief), or it is justified by a basic belief or beliefs
  2. it is justified by a chain of beliefs that is ultimately justified by a basic belief or beliefs.

An analogy to explain this idea compares foundationalism to a building. Ordinary individual beliefs occupy the upper stories of the building; basic, or foundational beliefs are down in the basement, in the foundation of the building, holding everything else up. In a similar way, individual beliefs, say about economics or ethics, rest on more basic beliefs, say about the nature of human beings; and those rest on still more basic beliefs, say about the mind; and in the end the entire system rests on a set of beliefs, basic beliefs, which are not justified by other beliefs, but instead by something else.

Foundationalism seeks to escape the regress argument by claiming that there are some beliefs for which it is improper to ask for a justification.

A belief is basic iff it is justified, but it is not justified by other beliefs. This requires that sensory perception justify basic beliefs. Others claim that an event of perception can begin a chain of belief. An objection to this idea is that a hallucination can cause an event of perception without corresponding to reality.

Foundationalists support their idea by claiming that sense experience can be a belief in itself. For example, suppose that one claims that one had fallen and scraped one's knee as a child. With no witnesses or other records, there is no fact which can support this belief except that one remembers it. In effect, the belief that one scraped one's knee is supported by one's memory of having scraped one's knee. This raises the question of what it is that makes one believe that one is justified in believing this sensory memory. Ultimately, then, this sensory belief is justified by another belief, that one's memory is reliable and true.


Finally, perhaps the chain loops around on itself, forming a circle. In this case, the justification of any statement is used, after a long chain of reasoning, in justifying itself, and the argument is circular. This is a na´ve version of coherentism.

Coherentism is the belief that an idea is justified iff it is part of a coherent system of mutually supporting beliefs (i.e., beliefs that support each other). In effect Coherentism denies that justification can only take the form of a chain. Coherentism replaces the chain with a holistic approach.

The most common objection to na´ve Coherentism is that it implies that circular justification is acceptable. Meaning that in this view, P ultimately supports P, which is not an acceptable form of reasoning; this logical error is called begging the question. Coherentists reply that it is not just P that is supporting P, but P along with the totality of the other statements in the whole system of belief.

Another issue is that it accepts any belief that is part of a coherent system of beliefs. In contrast, P can cohere with P' and P" without P, P' or P" being true. To respond that the system of beliefs has to be derived from experience in reality would be to replace Coherentism with a form of foundationalism. Instead, Coherentists might say that it is very unlikely that the whole system would be both untrue and consistent, and that if some part of the system was untrue, it would almost certainly be inconsistent with some other part of the system.

A third objection is that some beliefs arise from experience and not from other beliefs. An example is that one is looking into a room which is totally dark. The lights turn on momentarily and one sees a white canopy bed in the room. The belief that there is a white canopy bed in this room is based entirely on experience and not on any other belief. Of course, possibilities exist, such as that the white canopy bed is entirely an illusion or that one is hallucinating, but the belief remains well-justified. Coherentists might respond that the belief which supports the belief that there is a white canopy bed in this room is that one saw the bed, however briefly. This appears to be an immediate qualifier which does not depend on other beliefs, and thus seems to prove that Coherentism is not true because beliefs can be justified by concepts other than beliefs. However the experience of seeing the bed is indeed dependent on other beliefs, about what a bed, a canopy and so on, actually look like.

Other views

Common Sense

The method of common sense espoused by such philosophers as Thomas Reid and G. E. Moore points out that whenever we investigate anything at all, whenever we start thinking about some subject, we have to make assumptions. One tries to support one’s assumptions with reasons, one must make yet more assumptions. Since it is inevitable that we will make some assumptions, why not assume those things that are most obvious, the matters of common sense that no one ever seriously doubts.

"Common sense" here does not mean old adages like "Chicken soup is good for colds" but statements about the background in which our experiences occur. Examples would be "Human beings typically have two eyes, two ears, two hands, two feet", or "The world has a ground and a sky" or "Plants and animals come in a wide variety of sizes and colors" or "I am conscious and alive right now". These are all the absolutely most obvious sorts of claims that one could possibly make; and, said Reid and Moore, these are the claims that make up common sense.

This view can be seen as either a version of foundationalism, with common sense statements taking the role of basic statements, or as a version of Coherentism. In this case, commonsense statements are statements that are so crucial to keeping the account coherent that they are all but impossible to deny.

If the method of common sense is correct, then philosophers may take the principles of common sense for granted. They do not need criteria in order to judge whether a proposition is true or not. They can also take some justifications for granted, according to common sense. They can get around Sextus' problem of the criterion because there is no infinite regress or circle of reasoning, because the buck stops with the principles of common sense.

Critical philosophy

Another escape from the diallelus is critical philosophy, which denies that beliefs should ever be justified at all. Rather, the job of philosophers is to subject all beliefs (including beliefs about truth criteria) to criticism, attempting to discredit them rather than justifying them. Then, these philosophers say, it is rational to act on those beliefs that have best withstood criticism, whether or not they meet any specific criterion of truth. Karl Popper expanded on this idea to include a quantitative measurement he called verisimilitude, or truth-likeness. He showed that even if one could never justify a particular claim, one can compare the verisimilitude of two competing claims by criticism to judge which is superior to the other.


The pragmatist philosopher William James suggests that, ultimately, everyone settles at some level of explanation based on one’s personal preferences that fit the particular individuals psychological needs. People select whatever level of explanation fits their needs, and things other than logic and reason determine those needs.

In The Sentiment of Rationality, James compares the philosopher, who insists on high degree of justification, and the boor, who accepts or rejects ideals without much thought:

“The philosopher’s logical tranquillity is thus in essence no other than the boor’s. They differ only as to the point at which each refuses to let further considerations upset the absoluteness of the data he assumes.”


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