Can scepticism be refuted by writing it ‘skepticism’?

This is a copy of the paper I’m handing in tonight for my epistemology course. This is the only work required for submission. There’s still two classes left (tonight and next week) but it’s been a pretty interesting first dip into epistemology.

Can Scepticism Be Refuted?


Tim Dickinson

It is clear that humans seek knowledge. We know this about ourselves and we see it in others, to some degree or other. At minimum, we want to know things because of evolutionary selection, since animals that seek reusable knowledge and reason inductively are more likely to survive than those that do not. There may be less utilitarian reasons for this seeking as well: a desire for self-growth, for example, or an intrinsic value on truth. In light of this apparent importance, the question of scepticism – whether we can in fact ever really know anything – is therefore due some consideration. Can scepticism be refuted?

In this paper I will describe how scepticism can be broadly separated into Agrippan and Cartesian forms, and how these forms cast doubt on our ability to acquire knowledge. I will show that sceptical doubt is powerful because it seems basic and intuitively grasped, and is not so esoteric as to appear dubious. I will then demonstrate how these forms of scepticism can be refuted with theories of coherence and contextualism that are equally intuitive.

Forms of Scepticism

There is a form of scepticism more properly identified as incredulity. This is what I mean when I describe the viewpoint of someone who tends to reject ideas which lack supporting evidence; this is the opposite of dogmatism. I will not consider this form of scepticism here, since it is not general. This casual scepticism does not exclude any knowledge for which I do have evidence (and is, in fact, generally regarded as a good and important part of any analytical viewpoint). What I will examine is philosophical scepticism: the claim that acquiring knowledge is inherently impossible.

I will discuss two forms of philosophical scepticism: Agrippan and Cartesian. I will not include fallibilism because it is not radical scepticism: it is simply the view that I may be mistaken about some things and can probably not be certain of much, not that it is impossible for me to know things to be true. In fact, if we know anything, it seems likely to me that the fallibilist view is the right one, and that we can be absolutely certain about very little (if anything at all).

Agrippan scepticism is an ancient form that developed from earlier Greek scepticism[1]. It implies that beliefs always rely upon an unfounded assumption, circularity, or an infinite regress[2]. That is, every attempt I make at justifying why I have knowledge must end up at some fundamental assumption upon which I build the rest of my knowledge; or my reasoning ends up in a loop where my justifications all rely on one another; or my justification can always be met with another request for justification. These are simple, yet powerful, obstacles. Since, according to the Agrippan view, all attempts at justification must fall into one of these traps, no knowledge is possible. To refute Agrippan scepticism, I will thus have to demonstrate that justification does not always fall afoul of these traps.

Cartesian scepticism derives from the philosophy of Descrates[3], who questioned the possibility of asserting that we have reliable knowledge of the external world. Others have built upon this viewpoint, and what is now called Cartesian scepticism may be regarded as the claim that – given all the evidence I will ever have to make some claim about the world – an alternative explanation that makes my claim false is just as likely to be true. This form of scepticism implies that justified beliefs must be either direct knowledge or inferred (deductively or inductively) from direct knowledge. This is sometimes expressed as a problem of underdetermination (i.e., I have inadequate evidence necessary to decide that my belief counts as knowledge). To refute Cartesian scepticism, I will thus have to show that I may sometimes have sufficient justification for knowledge.

Refuting Agrippan Scepticism

As discussed above, to refute Agrippan scepticism I will have to show that unfounded assumptions, circularity, and infinite regress do not block all claims to knowledge. I will consider the first two problems by examining existing models of knowledge that claim to overcome them. I will then go on to propose that a model might exist that circumvents the third problem.

Foundationalism – the model that I have certain fundamental, directly knowable true beliefs, upon which others can be built – claims to refute to Agrippa’s problem of assumptions. Foundationalism would say that these basic beliefs are neither unfounded nor assumed: they, at least, are justified. I find foundationalism unconvincing. What special knowledge requires no justification? Some level of assumption seems difficult to avoid, at least for anything beyond self-awareness. Foundationalism does not appear to be a theory that defeats Agrippan scepticism.

Coherence – the model that our knowledge is a network of mutually supporting true beliefs – claims to refute the second Agrippan problem, that of circularity. A coherence view would imply that circularity of justification is not an obstacle to knowledge. A complex, non-contradictory network of knowledge implies a tested, reliable system of knowledge in much the same way that the subsets of knowledge we are more familiar with (e.g., physics) do. As such, a coherence system of knowledge gains force as it becomes more comprehensive and increases in accuracy. To maintain sceptical doubt in the face of such force requires an increasingly infallibilist position (that our justification and knowledge must be free of the chance of error). I note that Williams[4] claims that coherence requires me to make assumptions about the validity of my whole system of my knowledge, and is therefore simply another form of foundationalism. I disagree with this view. The modularity of my knowledge, or my inability to hold the entirety of it at all times in my mind, does not threaten my justification: only a poor standard of justification does. Coherence therefore appears to be a strong possibility for refuting the Agrippan assertion that circularity should make us sceptical about our knowledge.

A similar line of argument holds for theories of knowledge that are part of an infinite regress, Agrippa’s third sceptical challenge. I recognize that this position is not commonly given credit. In fact, Agrippa’s scepticism is usually described as a ‘twin-horned’ dilemma – comprised of assumption and circularity – upon which the non-sceptic impales himself whilst attempting to avoid the infinite regress of justification. However, I see nothing inherently impossible about an infinite chain of justification. Infinite series are commonly used in mathematics and are both understood and applied practically. I believe that our distaste for infinite regression lies in our perception of a direction of time. Few people have difficulty imagining an infinite progression into the future. Modern physics has shown that time is in fact a dimension more similar to the spatial ones that we had previously supposed[5]. I will not claim that this is strong evidence that an infinite regress refutes Agrippan scepticism in the same way that a coherence system does. I will here simply assert that a system of knowledge justified on an infinite regress cannot be rejected out of hand.

Refuting Cartesian Scepticism

Cartesian scepticism is sometimes illustrated by Descartes’ ‘Evil Deceiver’ or ‘dreaming’ scenarios; or, more recently, by the ‘Brain in a Vat’ scenario. Putnam claims to refute this sceptical view by using semantic externalism to claim that if I am a brain in a vat, then the statement ‘I am a brain in a vat,’ is incoherent, and therefore false[6]. I reject this argument as unconvincing; Putnam simply points out that some things that may be possible areconceptually impossible.

Phenomenalists claim to refute Cartesian scepticism by stating that all I can ever know is my experience, my sense-data. This sense world, they claim, is the only one that can exist for me. They believe that they thus defuse the problem of scepticism because there is nothing for me to be deceived about. This view strikes me as an unsatisfactory cheat. Everything about my experience seems to imply an objective world where things take place without me, and so it seems right that I should give that world credit and attempt to know it.

Grayling[7] stages an elaborate refutation of scepticism. As discussed above, however, the problem of scepticism is significant not only because of its implications about the truth of our knowledge, but also because it is so intuitive (themes in popular culture support this). Grayling’s position requires transcendental arguments and a discussion of realism that, I feel, are not sufficiently intuitive to combat such fundamental doubts.

To refute Cartesian scepticism I will therefore need to show that the evidence I am able to collect does not always underdetermine my justification of my beliefs about the external world. My first problem is then how I am to decide what constitutes sufficient justification. I have previously rejected an infallibilist requirement for certain justification as needlessly prohibitive. What lesser level of justification will do?

My approach is rooted in my everyday experience. How do I typically decide what constitutes sound justification in my day-to-day life? I judge the circumstances. I assess what I know of the source of the information; I try to consider my own frame of mind; I take into account the urgency attending the knowing and the importance of the outcome. The type of justification I might require to know that I smell my dinner cooking is likely to be quite different than that I might require from someone who is explaining a mathematical proof to me.

This view is the contextualist theory. I believe that it offers the best way to refute the sceptical position. The contextualist position is broadly that the level of justification required to be epistemically responsible depends on the circumstances. I can recognise the contextualism of semantics (e.g., we all use the words ‘I’ or ‘my brother’ in the same way, but refer to different people when we do so). Similarly, I recognise that I apply different levels of justification in my everyday decisions about knowledge (as above, I adjust my justification requirements depending on what I’m being asked to believe, who’s doing the telling, etc.). Contextualism says that there is an appropriate epistemological standard of justification depending on the context of what it is that I am being confronted with. If I am consistent and intelligible with my application of these standards, then there seems little reason to believe that contextualism is failing as a system for justification (even if I sometimes make errors).

Williams claims that, in addition to being a reliable view of knowing the external world, the contextualist view attacks hidden premises of scepticism[8]. Cartesian scepticism, he claims, inherently imposes a priority of experiential knowledge over direct knowledge of the world[9]. For the contextualist, there is no reason to grant that this context-invariant assumption is true. Cartesian scepticism amounts, he says, to a form of foundationalism. This undermines the sceptical claims, since they now depend on more complex theoretical assumptions and are not as basic and intuitive as before. I find this argument convincing. There are many instances of successful thought experiments predicting nature, for instance, which implies that sense-data may not always automatically supersede other knowledge about the world. Contextualism therefore seems to not only provide a reasonable system of justification within the framework of coherence, it challenges scepticism at its root.


I believe that coherence theory has the best chance of avoiding Agrippan scepticism (and that a theory of knowledge based on infinite regress might also do), since it shows how a justified system of knowledge can exist, self-contained, without supposition to support it. With that basic structure in place, I believe that contextualism then provides a means for the justified acquisition of knowledge.

[1] Hamlyn, D.W. (1990), The Penguin History of Western Philosophy, 85-86.

[2] Williams, M. (2001), Problems of Knowledge: A Critical Introduction to Epistemology, 61-63.

[3] Hamlyn, 138.

[4] Williams, 137.

[5] Hawking, S.W. (1988), A Brief History of Time, 143-153.

[6] Putnam, H. (1992), ‘Brains in a Vat’, in K. DeRose and T.A. Warfield (eds.),Scepticism: a Contemporary Reader, 385-399.

[7] Grayling, A.C. (1985), The Refutation of Scepticism.

[8] Williams, 187.

[9] Williams, 189.

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