In his 1966 book Theory of Knowledge Roderick Chisolm provides two sets of questions:

  1. What do we know? or What is the extent of our knowledge?

  2. How do we know? or What is the criterion for deciding whether we have knowledge in any particular case?

Chisolm describes different ways of responding to these questions. One of them is the skeptic. The skeptic charges that, since we cannot have an answer to one set without first answering the other set and vice versa, we are plunged into an escapable vicious circularity and are unable to answer either of them.

Have any philosophers prior to Chisolm taken this problem (or something like it) seriously and come up with an answer of their own with which they could rebut the skeptic's answer? If so, who, and how did they do it?

  • Added links and fixed a minor typo.
    – J D
    Nov 19, 2021 at 18:48
  • Your "something like it" makes the question futile. As May quipped:"However, the hope of finding a first comes to grief because of the historically dynamic character of ideas. If we describe a result with sufficient vagueness, there seems to be an endless sequence of those who had something within the vague specifications". Indeed, we can relate it to anything from Agrippa's trilemma and Cartesian circle to any foundationalist, or not, epistemology, starting with Plato and Aristotle. On the other hand, Chisholm's 2-question formulation was novel, so nobody could "answer" it before him.
    – Conifold
    Nov 19, 2021 at 23:19

1 Answer 1


Short Answer

Yes, many philosophers too numerous to cite have taken up the task of responding to the problem of skepticism. Today, most professional philosophers reject radical forms of skepticism, and like Chisholm, have an argument of why we can know, despite the fact we can be fooled. This position might be broadly understood as fallibilism.

Long Answer

The easier question to answer is which philosophers haven't taken up the discussion of overcoming the objections of skepticism (SEP) to knowledge. Since you used the term 'circularity', let's just briefly review the Agrippan Trilemma. If one reasons about belief and knowledge, one is essentially confronted with three techniques:

In epistemology, the Münchhausen trilemma, also commonly known as the Agrippan trilemma, is a thought experiment intended to demonstrate the theoretical impossibility of proving any truth, even in the fields of logic and mathematics, without appealing to accepted assumptions. If it is asked how any given proposition is known to be true, proof may be provided. Yet that same question can be asked of the proof, and any subsequent proof. The Münchhausen trilemma is that there are only three ways of completing a proof:

The circular argument, in which the proof of some proposition presupposes the truth of that very proposition
The regressive argument, in which each proof requires a further proof, ad infinitum
The dogmatic argument, which rests on accepted precepts which are merely asserted rather than defended

So, from Antiquity, the problem of dealing with skepticism of knowledge has been a primary preoccupation of philosophers. We can speculate to the reason, and that is inherent to examining naive realism, one is immediately struck by certain situations such as confabulation, illusion, and deception that beg the philosopher to entertain the notion that knowledge is mere belief. In fact, the guiding principle of the epistemologist is to show how belief can be justified adequately as knowledge. Historically, the reliance has been on a definition that is commonly called JTB which was challenged seriously by Gettier resulting in the adoption of additional theoretical criteria commonly referred to as JTB+.

Skepticism can become technically sophisticated in terms of the nature of the propositions one characterizes. From SEP:

One interesting distinction between kinds of philosophical skepticism pertains to the question whether they iterate. Thus, consider skepticism about the future: the claim that the only justified attitude with respect to propositions about the future is suspension of judgment. That kind of philosophical skepticism overlaps partly with ordinary skepticism about the future.

Unless one adopts faith as a first principle which is a common decision among theologians, one generally settles for general forms which can be expressed as broadly Phyronnian (SEP):

Recall that, according to Pyrrhonian Skepticism, suspension of judgment is the only justified attitude with respect to any proposition (yes, including the proposition that suspension of judgment is the only justified attitude with respect to any proposition).

This sort of thinking might be seen as culminating in Descartes' demon or in a more contemporary palatable form brain-in-a-vat. Suffice it to say, most philosophers devise a response the to problem of skepticism and fall firmly into the territory of fallibilism (IEP), which is almost universally embraced by well-educated, contemporary philosophers as post-skeptic attitude about uncertainty. From IEP:

Fallibilism is the epistemological thesis that no belief (theory, view, thesis, and so on) can ever be rationally supported or justified in a conclusive way. Always, there remains a possible doubt as to the truth of the belief. Fallibilism applies that assessment even to science’s best-entrenched claims and to people’s best-loved commonsense views. Some epistemologists have taken fallibilism to imply skepticism, according to which none of those claims or views are ever well justified or knowledge. In fact, though, it is fallibilist epistemologists (which is to say, the majority of epistemologists) who tend not to be skeptics about the existence of knowledge or justified belief. Generally, those epistemologists see themselves as thinking about knowledge and justification in a comparatively realistic way — by recognizing the fallibilist realities of human cognitive capacities, even while accommodating those fallibilities within a theory that allows perpetually fallible people to have knowledge and justified beliefs.

Once you are introduced to the ideas of skepticism prevalent in Antiquity (SEP), be they from the classical thinkers or from contemporary ones, it helps to have some preparation for examining the entire legacy of skeptical thinking. One possible resource for addressing that need is Epistemology: a Contemporary Introduction to the Theory of Knowledge by Robert Audi. In his intro of the first edition, he writes on page ixx:

One of my primary aims is to facilitate the reading of [historical] philosophers [who address justification of belief], especially their epistemological writings. It would take a very long book to discuss representative contemporary epistemologists or, in any detail, even a few historically important epistemologies...

So, to answer, yes. Other philosophers. Lots of 'em, too many to cite. A good start would be the bibliography of epistemology (SEP). Good luck!

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