The Skeptical Tradition

The Skeptical Tradition - M. Burnyeat, University of California Press


ISBN: 978-0520037472

READ: 2016-12-24

EDITOR: Myles Burnyeat


Revisiting how ancient skepticism has shaped the history of western thought has been a valuable philosophical exercise. Once the skeptical problem has been recognised for its full epistemologically destabilising powers, I believe, it is the philosopher’s duty to find an adequate response to the threat of the very possibility of knowledge. Indeed, as Kant remarked, present argumentative weapons might not have been developed without the influence of skeptical thought1)Barry Stroud, ‘Kant and Skepticism’, in The Skeptical Tradition (University of California Press, 1983) .

I will dare to present in the following brief chapters the most peculiar and striking features of the struggle for and against the skeptical challenge, as it has been carried out in the history of ancient and modern thought.


The Motivation of Greek Skepticism – an essay by David Sedley

Ancient skepticism stood for the impossibility of saying anything about the nature of external objects, that people could only say how they appeared to be through sensory perception. Although ancients never fully questioned the existence of external objects, Sextus Empiricus’s skeptical armament leaves that possibility widely open. Besides realism, another characteristic feature of ancient times was to consider philosophy as a therapeutic mean; it is no surprise, then, that even skepticism was set forth as a compelling recipe to attain happiness.

Although the Skeptic chose (literally) to be called an ‘Inquirer’, as to underline his open-mindedness in opposition with the disposition of the dogmatist, he will expose his commitment to suspension of belief by asserting that “to every argument an equal argument is opposed”. This is to say that although he still has not found conclusive reasons to prefer one argument over another, he would not change his mind even in the future: he will eventually find new proofs to balance dogmatic arguments, bringing him back to epoche2)David Sedley, “The Motivation of Greek Skepticism”, in The Skeptical Tradition (University of California Press, 1983) p.21. Furthermore, if epoche could somehow be justified as an end, since no convincing argument has been produced yet to move one to assent, it is much less conclusive that one should uphold ataraxia as the philosophical aim, as Sextus does. In Sextus’s framework, epoche is the mean to get to ataraxia. The story goes that ataraxia emerged as if ‘by chance’ in skeptics’ minds after embracing epoche, but that certainly does not dispel the ghost of belief bias as a support of an unquestioned ethical commitment.



The Stoicism of The New Academy – an essay by Pierre Coussin

Arcisilaus, one of the teachers of the Platonic Academy, shows through a reductio ab absurdum that the Stoic sage has to end up withholding assent: since having an opinion means to assent to something, not to have any opinion means that he must not assent to anything. Thus Arcisilaus’ skepticism would be a consequence of Stoic doctrine, not one of his own. “Since everything is inapprehensible, the Sage can only give assent to the inapprehensible, so he will withhold assent.”3)Pierre Coussin, “The Stoicism of The New Academy”, in The Skeptical Tradition (University of California Press, 1983) p.35

While Stoic, and therefore Academic, epoche is voluntary, skeptics are constantly in a dimension of doubt, they don’t assent nor deny. To Epicureans assent bears no meaning, since all perceptions are true. Arcisilaus moved from Stoic material to develop his counterarguments to induce epoche necessarily; he retained a pragmatic take of skepticism by affirming that withholding assent shouldn’t prevent one from acting, as he will act upon what appears to him. Academic philosophy is therefore presented by Coussin as an heterodox Stoicism, for it would not have existed without Stoic logic; Academic criticisms helped de facto the refinement of Stoic arguments.


The Ten Tropes of Aenesidemus  – an essay by Gisela Striker

The Ten Tropes rests on two different strategies: undecidability – by leaving open the possibility of eventually finding out what is true – and relativity – which aims at showing that there cannot be something we can infer to be true about the nature of anything. Since the latter is more of a negative dogmatism, the kind of skepticism which is usually attributed to the New Academy, Phyrronian skepticism relies on the first to bring on its epoche, and following ataraxia.

The inconsistency which Striker brings about is that the Tropes, as Sextus presents them, are made to underline the argument of relativity. The author stresses that it is not a matter of negligence: Sextus had to do so, in order to impress upon the reader the persistence of undecidability by pointing out how things appear to be different in relation to the observer, and even more so in their relational content.


Can the Skeptic Live his Skepticism? – an essay by Myles Burnyeat

The Humean challenge to Phyrronian skepticism: a skeptic cannot live up to his ‘theoretical’ standards because

  1. what the Phyrronist invalidates through reasoning is nothing less than reason and belief;
  2. a man cannot live without believing something; the argument is therefore that it will be impossible to live as a skeptic.

What Sextus answers:

  1. that he can easily give up believing in something and simply live by what appearances say about the world;
  2. that giving up reason can be done as a result of argumentation, i.e, of reason.
In Skepticism, conflicting arguments are equipollent, they ‘carry the same weight’; to dismiss the skeptical challenge, it should be enough to employ a polished probabilistic theory of assessment, and gather a little more data to move the scale’s needle one way or the other.


Burnyeat reminds us that in ancient times the Skeptic dealt exclusively with the true essence of external objects, since all ancient philosophical traditions hold up realism; true or false propositions could be made about the nature of things which are non-evident, whereas appearances did not have any truth value, because they imposed themselves upon the subject as evident.4)Psychology has been decisive in highlighting the unreliability of appearances’ reports, i.e. the stimulus-error. Thus Burnyeat remarks that

“All belief is unreasonable precisely because, as we are now seeing, all belief concerns real existence as opposed to appearance.” p.122

Sextus’s claim is that after our inquiry has been carried out, once we face the undecidability of conflicting beliefs, we find ourselves in the necessity of giving up belief; the Skeptic has no problem with that, he even claims that epochè brings him to experience ataraxia, and he can hence live by following appearances and withhold assent regarding the true nature of non-evident things.


How is then one to simply follow appearances to guide his living? Here is the skeptical recipe for conducting a life without belief:

  1. the Skeptic acts under guidance of nature;
  2. he is constrained by what the body demands (physical needs), he is thus not absolutely impassible; rather, suspension of belief will greatly alleviate his sufferings by removing additional misery to occasional physical distress;
  3. he will follow customs and traditions, while suspending judgement on their truth or falseness;
  4. he practices an art of any kind, so that he will be busy with something.5)Myles Burnyeat, “Can the Skeptic Live His Skepticism?”, in The Skeptical Tradition (University of California Press, 1983) p.126

It is important to notice that when Sextus talks about “appearances”, he refers to “both objects of sense and objects of thought.”6)ibid, p.127

Thus in Sextus there is no opposition or choice between appearances and realities, rather “questions about how something appears and questions about how it really and truly is”7)ibid, p.129, and the latter is shown to be impossibile due to the undecidability of conflicting appearances.

It turns out, then, that the life without belief is not the mental blank one might at first imagine it to be. It is not even limited as to the subject matter over which the sceptic’s thoughts may range. Its secret is rather an attitude of mind manifest in his thoughts. He notes the impression things make on him and the contrary impressions they make on other people, and his own impressions seem to him no stronger, no more plausible, than anyone else’s.

[…] Thus the withdrawal from truth and real existence becomes, in a certain sense, a detachment from oneself.” p.129


As I have already remarked, the Skeptic is passive in his assent to impressions, and he is equally forced to suspend belief. How does then ataraxia follow? Hellenistic moral psychology held that emotions depend on belief; thus, removing beliefs would alleviate from feeling good or bad about something, i.e. emotions, which would not eliminate the physical constraints of hunger, thirst, and so on. “The life without belief is not an achievement of the will but a paralysis of reason by itself”8)ibid, p.133; it is as though Sextus wants to bring us to a pre-conceptual, animal heaven, where the development of meaning is suppressed in name of unmovable bliss. One may of course wonder how joyfulness can be achieved without building a sense of how one’s life should be led.


Anyway, can we really say that Sextus completely eschews belief? We may interpret his most stark sentences (“all things appear relative”) as a belief or as a chronicle of a held belief, or as a chronicle of a belief that he tends to support.

One possible defence is that by suspending judgement, the Skeptic simply does not take on the dogmatic type of belief, that which asserts the impossibility of knowing anything about the non-evident. The point is, it is quite hard to distinguish between a non-dogmatic and a dogmatic belief, since dogma can be understood in a broader sense too, that of accepting perceptual experience as it is, of which Sextus makes large use of; moreover, it is impossible to disengage from belief without breaking its link with the truth.9)ibid, p.137 Since belief has an unbreakable connection with truth, and since Sextus claimed that we are forced to suspend belief about the truth of any proposition, we cannot say that he held any belief.


There is another point to be made about the supposedly non-epistemic quality of Sextus’s appearance-statements: to hold that p (suspension of belief) because of a certain argument (the undecidability between conflicting appearances) “is hardly to be distinguished from coming to believe that p is true with that argument as one’s reason.”10)ibid, p.138

“If the sceptic works thorough reasoned argument to the point where the reasons on either side balance and reason stultifies itself, if his arguments are (in the now famous phrase) a ladder to be thrown over when you have climbed up, then we must insist that they make their impact through the normal operations of our reason.” p.139

Again, the main problem should be that of trying to account for ataraxia as the indisputable result of the skeptical enterprise. If the Skeptic claims, as he in fact is, to remain open to further inquiry, that should not be understood as the possibility of discovering that in fact some arguments may be stronger than others, for that outlook would secretly imply a search for answers, and with it a kind of anxiety that the Skeptic deliberately wants to get rid of.

Ataraxia is hardly to be attained if he is not in some sense satisfied – so far – that no answers are forthcoming, that contrary claims are indeed equal. And my question is: How can Sextus then deny that this is something he believes?

I do not think he can. Both the causes (reasoned arguments) of the state which Sextus calls appearance and its effects (tranquillity and the cessation of emotional disturbance) are such as to justify us in calling it a state of belief. p.140

In other words, the Skeptic could not really achieve ataraxia if, to some extent, she would not put herself in a position where she tends to think that opposite claims would carry the same weight on and on; we should then count this first-level disposition as ‘belief’. That is to say, that reasons do shape the Skeptic’s thinking process, even though she reports that reason has no epistemic value in defining what is true. A life without belief would thus not be possible.


Ancient Skepticism and Causation – an essay by Jonathan Barnes

The problem with Sextus’s attack to causation is that the language he uses to complete his arguments bears inevitably some causal power. He is a champion of Life, in opposition to Philosophy and Belief; and Life is the realm of Common Sense.

“Skepticism is directed against Belief or dogma; dogma is defined as ‘assent to some item from among the nonevident objects of inquiring in the sciences.’ … It emerges that the ‘nonevident objects’ in question are things ‘which do not have a nature capable of falling under immediate observation.’” p.157

Thus Skeptics retain the common sense knowledge of causation, that which can be known by evidence, and discard first-principle-like notions of causality.


A problem with skeptical arguments in general, if they are not well-crafted, is to leverage an argument from disagreement to induce skepticism about certain issues. Barnes although remarks that it is not the mere fact of disagreeing that should cast doubt, rather reasons which support that disagreement:

“Admittedly, if there is reasoned disagreement, then that may cast doubt upon the explanation; but in that case is not the disagreement itself, but rather the reasons for it, which cast the doubt. … It is not your disbelief, but the reasons for your disbelief, which may properly lead me to doubt.” p.166


A further criticism about causation, which will be detected and improved upon by Gassendi (see the following chapter), is Aenesidemus’s second mode, by which every theory that one could come up with will be underdetermined by sense-data.11)An account of underdetermination of theories by data in contemporary skeptical arguments could be found in my short review (forthcoming) of Stroud’s The Significance of Philosophical Scepticism, 1984 (New York, Oxford)  12)Between page 173 and 175, for those who might be particularly interested in how Stoics refined their theory of causation under the pressure of skeptical arguments, it is described the process by which the theory of agency causation develops into a theory of event causation: it is not an agent being the cause of an effect, rather a specific event to be cause of another


The other argument which is employed by Skeptics against causation relies upon the Modes of Agrippa, by which one should not be able to infer the cause of anything without falling in an infinite regression of causality. Here is how Barnes answers to the skeptical challenge, charging the skeptic to have proposed an ignoratio elenchi:

“If the proponent of efficient causation is to ground his thesis, then he must indeed produce a ‘cause’ or reason for believing that there are causes; but he is under no obligation to cite an efficient cause.” p.179

Barnes nevertheless grants that the skeptical argument has some power, for it forces the dogmatist to narrow and clarify his theory of causation:

“If we are to justify a belief in causes, we cannot do so by any direct form of argumentation: either causes – or, if I may use the expression, ‘becauses’ – are a fundamental presupposition of thought; or they are immediate data of experience – things to be perceived, not to be argued for; or their existence must be shown by way of some ‘transcendental’ argument.” pp.179-180


Another issue with causation is the problem of time: the skeptical argument tries to show that (1) Causes precede their effects in time, and (2) Causes do not precede their effects in time; therefore, causes do not exist. We can easily picture a possible example for each: (1) We say that when a ball breaks the window, then causes precede their effects; (2) We should not be able to call the ball a ’cause’ of the window being broken before that fact actually happens; cause and effect are modal reciprocal, and they do therefore exist at the same time. In other words, because A exists as a cause of B exactly when B is produced, then it is not possible for A to exist as a cause of B prior to B being produced as an effect of A.

How should one tackle this problem? Barnes suggests that the misleading point in the argument is to consider causing as a datable event, instead of simply analysing two events – the thrown ball and the broken window – one of which entails the other in a causal relationship.

“In an outmoded jargon, causal relations are not real but rational. The fundamental error in Sextus’s main argument against causation is that of treating causing as a datable event, an occurrence in the world. It is a piquant thought that we can refute a skeptical argument against causation by insisting that causation itself is unreal.” p.186

By ‘causation is unreal’, again, the author means that causation cannot be identified as an event that could be somehow dated between cause-event A and effect-event B.


Augustine against the Skeptics – an essay by Christopher Kirwan

The original , pre-Cartesian thought that Augustine raises to meet the skeptical challenge is the “Si fallor, sum”:

“If Augustine believes something erroneously, he exists

If Augustine exists, he does not believe erroneously that he exists.” (p.221)

These two propositions jointly met Zeno’s condition for knowledge, by which something in order to be true must bear a sign that cannot come from anything else but its proposition, so that the proposition must have the following features: to be believed by someone, without it possibly be believed erroneously.

“The former condition [that the proposition is believed by someone] is fulfilled by anyone who recognises [any proposition] as (a) among his own beliefs, and sees the force of Augustine’s proof that (b) he cannot believe [it] erroneously; and the latter condition is fulfilled by anyone who sees the force of the simple little proof just given that no falsehood can possess features (a) and (b) jointly. If anything can be manifest, these facts can be.” p.221


The Rediscovery of Ancient Skepticism – an essay by C.B. Schmitt

Some historical details about the revival of Skepticism in the Renaissance: the latin word scepticus itself began to be used in that time, after Diogenes Laertius’s work had been translated.

Another interesting fact about the influence of skeptical thought is that Skepticism survived in Byzantium, shaping in part Eastern Christianity’s theology. It was then brought in Europe through Italy during the 15th century, and subsequently, in the 16th century, as Italian Renaissance began to fade out, it migrated to Northern Europe.

As with Platonic ideas, which have been exploited for different purposes during the history of thought, Skepticism in the modern era has been used both for and against religion.


Gassendi and Skepticism – an essay by Ralph Walker

The Modern Era brings about an even more radical turn for skptical arguments: he problem of the external world13)With regards to the problem of the external world, see my short review of Stroud’s The Significance of Philosophical Scepticism (forthcoming) . In fact, Sextus’s Skepticism goes beyond questioning the true nature of things, it threatens the truthfulness of all objective claims: the only thing he recognises as certain are mental representations (phantasiai).


Gassendi rephrases the problem of rationalism as follows: to rely upon rational human faculty by arguments that already assume its trustworthiness. Most empiricists acknowledge the circularity and reject to ground their statements on reason alone, by claiming that one must attain knowledge only through sense-perception; by the very issue of underdetermination of theories by data, which we previously encountered in Barnes’s essay, it is hard to understand anyway how empiricists could ground any of their theories on sense-data alone.

Following the same argumentative line, Gassendi anticipated Mill and Quine in the refutation of a priori knowledge. Quine, however, discredits Skepticism altogether by appealing to that very refutation:14)an extensive chapter about Quine and the skeptical problem of the external world could be found Stroud, 1984

“The very impossibility of satisfying the skeptic’s demand shows (or so it may be held) that the demand itself was out of place.” (p.332)

The only justification which someone could appeal to in order to meet the quest for knowledge is the commonsensical one, that which is held by many or accepted by those who we regard as authorities… in short, just what Aristotle claimed science should consist of.

As a naturalised epistemologist, though, Quine must be very careful to reject a priori knowledge and normative justifications: at that point he would just break his auto-imposed descriptive constraints and embrace himself a normative prescription.

A naturalised epistemologist, therefore,

“to the contention that knowledge is possible a priori can only reply by showing – or trying to show – that he can account for all that we believe we know without having need of that hypothesis. He cannot show that a priori knowledge is not possible; he can only argue that we do not, in fact, possess any.” p.332


Descartes’s Use of Skepticism – an essay by Bernard Williams

It is impossible to speak of Skepticism without including Descartes in the overview. Because the role of skeptical reasoning in Descartes’s philosophical project has been covered so widely in the literature, I want to highlight just a couple of points about Descartes’s concern with his pragmatic quest for science, by virtue of which he overthrows Skepticism as a mere loss of time.15)For a broader sketch of Descartes’s work, you may want to have a look at Descartes


After Descartes embarks on his hyperbolical skepticism, he is forced to find a solution, and comes up with the cogito and the God justification. Gassendi and Arnould, among others, immediately pointed out many limitations. We can look at how badly Descartes wants to overcome the skeptical impasse, by remembering that after he had recognised how perceptions could be systematically deceived, and after establishing the cogito and the divine warrant, however precarious it may seem, he rushes to set up the rational foundations of science, so that sensory perceptions can be properly systematised. His quest for objective knowledge is undeniably a quest for certainty.

That surely is a platitude; but it might be useful to remember Descartes’s pragmatic side to appreciate why he rejected so fiercely any skeptical challenge.

“The skeptic has no reasonable claim, in terms of practical reason, to make us spend time going round and round his problems, rather than making genuine progress with the problems of science.” (p.350)


Locke and Pyrrhonism: The Doctrine of Primary and Secondary Qualities – an essay by Martha Brandt Bolton

One of the favourite skeptical strategies is to point out at the incompatibility of sense-perception: that if S1 states that the honey is sweet, while S2 founds that it is not so, then we don’t really know what the nature of honey is. Locke answered by separating primary qualities – those which constitute the essence of an object: solidity, extension, motion, number and figure – from secondary qualities: being secondary qualities those which do not speak of the nature of the object, their eventual incompatibility cannot show the object to be unknowable; with respect to primary qualities, Locke thinks of them to be either true or false – the perception of an object shape, for example, if carried out in the same conditions, could hardly be mistaken between roundness and cubicness.


 The Tendency of Hume’s Skepticism – an essay by Robert J. Fogelin

“Hume’s skepticism and naturalism meet, for the state of moderate skepticism is viewed as a result of two causal factors: radical Phyrronian doubt on one side being moderated by our natural (animal) propensities to believe in the other.” p.399


Hume’s strategy is somehow dreadful: his mastery of skeptical arguments brings him initially to reduce knowledge to mere probability; then, almost as to show how destructive the skeptical progression becomes as it gains momentum, he reduces first-order probabilities to second-order probabilities, that is: probabilities of true perception can be doubted, so that the only available solution would that of formulating probabilities of true judgement about perceptions; and because those second-order probabilities could be doubted further, through an infinite regress, Hume ultimately gets from knowledge ‘to nothing’. Not even the so-called peritrope – which is often used to show that the skeptic undermines his own position – would work: skeptical reasonings survive, sometimes strengthened, sometimes weakened, ‘according to the successive dispositions of the mind’ (Hume). We may grant that

“Skeptical arguments are self-refuting, but this only puts us on a treadmill, since setting aside our skepticism and returning to the canons of reason inevitably puts us on the road yet another skeptical impasse. For Hume, skepticism is completely immune to rational refutation. Indeed, it is the fated end of all reasoning pursued without restraint.” p.402


Hume appeals then to the idea of naturalism as the ‘best explanation’ to account for the intuitive force of beliefs, in spite of the strength of the skeptical position – which, we should be reminded, states that epoche is not just a suspension of judgement, but of belief itself.

“Hume’s central idea seems to be this: If belief were fixed by processes of reasoning, then the skeptical argument […] would drive all those who have considered it to a state of total suspension of belief. Indeed, in our closet, such skeptical reflections can come very close to inducing this extreme state. Yet when we return to the affairs of daily life, our ordinary beliefs come rushing back upon us and our previous state will now strike us […] as amusing. But the restoration of belief is not a matter of reasoning and therefore cannot be explained on any of the traditional theories of belief formation where it is assumed that the mind comes to its beliefs by a process of reasoning.” p.403-4

We can appreciate how Hume posits that the traditional theory of belief is wrong, inasmuch as it is exclusively rational. It is not an attack to rationality, either; Hume simply wants to remark that in order to describe how it is possible that someone may come to believe anything after he has been brought to epoche by the skeptic, one needs to argue that some basic beliefs may not have any rational ground at all:

“Hume’s theoretical skepticism concerns arguments. In its various manifestations it shows the groundlessness of given beliefs. It is not aimed at nor does it have any tendency to diminish the force of those beliefs that spring up in us naturally.” p.407

Hume is a skeptic who finds himself unable to stop from having any belief. He deems that it is his natural instinct, which makes it so; it is not a state he actively reaches through some way of reasoning, he plainly finds himself in that position.

“In sum, Hume’s skepticism and his naturalism meet in a causal theory of skepticism itself.” p.410


Kant and Skepticism – an essay by Barry Stroud

This last chapter is somehow different: I liked Stroud’s lines so much for their clarity, that I could have barely written something better than a bad paraphrasing. Here we will focuse on Kant’s response to skepticism, a fierce reply to the ‘scandal to human philosophy and to human reason in general’, that ‘the existence of things outside us … must be accepted merely on faith16)Immanuel Kant, Critique of Pure Reason


The heart of the matter is that until one retains epistemic priority of perceptions over external reality, that is, that internal states are knowable in an easier way than its outer corresponding objects, then skepticism is the only possible solution. The question, therefore, relies on the argument that experience, in order to be possible, must necessarily be an immediate consciousness of an external state of affairs.

“If it is true that ‘inner experience in general’ is possible only if ‘outer experience in general’ is possible, and ‘outer experience’ is the immediate, direct perception of external things, then in order to know of the existence of things around us it is not required that we determine in each case or in general that there is an external reality corresponding to our perceptions.” p.418-9

“The realism that [Kant] wishes to show is the only correct view would deny the inferential and therefore problematic character of our knowledge of things around us in space. That is precisely why it is the only correct view; it is the only view that is incompatible with skeptical idealism, and hence the only view that can explain how our knowledge of the world is possible.” p.419

Idealism though has been shifted to the higher level of explanation, that of transcendental knowledge:

“The objects we perceive around us in space are dependent on our sensibility and our understanding. It is only because that is true that we can perceive those objects directly and therefore can be noninferentially certain of their reality. So some form of idealism is required, after all, in order to explain how our knowledge of the world is possible.” p.420

The epistemological twist that allows Kant to (presumably) annihilate the skeptic is what has been famously called the ‘Copernican Revolution’:

“Space and things in space are to be seen as ‘empirically’ real but ‘transcendentally’ ideal. Although idealism and realism are incompatible, they do not conflict if one is understood ‘transcendentally’ and the other ’empirically’. That is precisely Kant’s solution to the problem of how human knowledge is possible.” p.420


Objects do really exist out of us – in an empirical way, they are real; they further need a priori knowledge in order to be knowable by us:

“Realism is in part the view that objects exist in space independently of human or other perceiving beings, so it is quite obvious that at least that part of realism, understood ‘empirically’, is true.” p.421

“A transcendental investigation examines the necessary conditions of knowledge in general; it is the search for an understanding of how any knowledge at all is possible. And for Kant that amounts to an investigation of what we must know a priori if any knowledge of objects is to be possible.

[…] We could discover a priori, independently of experience, what the general conditions of knowledge are, only if those conditions were in some sense ’supplied by us’ or had their ‘source’ somehow ‘is us’, the knowing subjects, and not simply in an independently existing world.” p.422

How does that all link to the Cartesian problem? The Kantian solution forbids to extend particular doubt to a global skepticism:

“Kant’s refutation of idealism is meant to prove that if Descartes’s negative conclusion were true it would violate one of the conditions that make any experience at all possible.

[…] If we have any experience at all, we must be capable of direct experience of ‘outer’ things that exist quite independently of us in space, so our access to, and hence our knowledge about, things in space must be direct and unproblematic in a way that is invulnerable to philosophical attack of the sort Descartes tries to mount.” p.429


Transcendental idealism is quite peculiar in its own form: it allows ordinary language to talk about the objective existence of external objects, providing an adequate explanation of that very knowledge which aims at making it invulnerable to the skeptic’s spell.

“Our direct and unproblematic access to objects around us in space is possible, according to Kant, only because the things we are directly aware of in experience are appearances and are dependent on us. That idealist thesis in turn implies that we can have knowledge only about those things that are dependent on us. But when we say or believe in everyday life that we see a pencil or a piece of paper and thereby know that it is there, and we also believe that pencils and pieces of paper are things that are not dependent on us, we are not saying or believing anything that contradicts those idealist theses.” p.430

“In our ordinary empirical judgements about reality we do not commit ourselves one way or the other on the question whether reality in general matches up with or corresponds to the way it is perceived to be; so in claiming knowledge or certainty about the world we do no commit ourselves to the falsity of philosophical skepticism. Therefore we do not have to show on each occasion how we know that philosophical scepticism is false in order for our ordinary assertions of knowledge and certainty to be true and fully legitimate.” p.431

“The way in which the ordinary judgements are in general legitimised secures the result that, in making them, we are saying nothing about the way things are, transcendentally speaking.” p.432


The very last part of the essay sketches out one of the main 20th century antiskeptical arguments, the positivist verifiability principle of meaningfulness. The verifiability principle states that in order to gain knowledge about the world, one must be able to tell whether that knowledge is true or false, that is, it must be verifiable by empirical inquiry. Therefore, every proposition about the world that is verifiable, would be deemed as meaningful, while any proposition which lacks that property – precisely what fits the skeptical doubt about the external world – would simply be meaningless, and not worthy of any examination.

Stroud argues that such move is Kantian in spirit, although its authors (Carnap & Co.) wanted to remove any appeal to transcendental talk. It remains unclear whether the antiskeptical structure of the argument will resist, had the transcendental proof be removed.17)In Stroud, 1984, the author claims that in fact, it does not.

References   [ + ]

1. Barry Stroud, ‘Kant and Skepticism’, in The Skeptical Tradition (University of California Press, 1983)
2. David Sedley, “The Motivation of Greek Skepticism”, in The Skeptical Tradition (University of California Press, 1983) p.21
3. Pierre Coussin, “The Stoicism of The New Academy”, in The Skeptical Tradition (University of California Press, 1983) p.35
4. Psychology has been decisive in highlighting the unreliability of appearances’ reports, i.e. the stimulus-error.
5. Myles Burnyeat, “Can the Skeptic Live His Skepticism?”, in The Skeptical Tradition (University of California Press, 1983) p.126
6. ibid, p.127
7. ibid, p.129
8. ibid, p.133
9. ibid, p.137
10. ibid, p.138
11. An account of underdetermination of theories by data in contemporary skeptical arguments could be found in my short review (forthcoming) of Stroud’s The Significance of Philosophical Scepticism, 1984 (New York, Oxford) 
12. Between page 173 and 175, for those who might be particularly interested in how Stoics refined their theory of causation under the pressure of skeptical arguments, it is described the process by which the theory of agency causation develops into a theory of event causation: it is not an agent being the cause of an effect, rather a specific event to be cause of another
13. With regards to the problem of the external world, see my short review of Stroud’s The Significance of Philosophical Scepticism (forthcoming) 
14. an extensive chapter about Quine and the skeptical problem of the external world could be found Stroud, 1984
15. For a broader sketch of Descartes’s work, you may want to have a look at Descartes
16. Immanuel Kant, Critique of Pure Reason
17. In Stroud, 1984, the author claims that in fact, it does not.