To be delivered at Round Table: The Philosophy of David Hume, which takes place on 31st July 1999, as part of The 10th International Congress on the Enlightenment, at University College Dublin, Ireland.
In Section XII of the first Enquiry, Hume introduces a new system of classification of sceptical arguments, in which he contrasts the antecedent with the consequent scepticism, and then the mitigated with the excessive scepticism. In discussing the consequent scepticism, he first deals with the sceptical objections against the evidence of the senses, and distinguishes them into the trite and the profound topics, and when he proceeds then to the objections against the evidence of reason, he makes a parallel distinction between the popular and the philosophical arguments. The first objective of this paper is to make clear what Hume intends in making these parallel distinctions, by comparing the arguments in the Enquiry with those in the Treatise. I will argue that what characterizes the philosophical form of scepticism as opposed to the vulgar is that it is made free from common people's instinctive presuppositions concerning human cognitive faculties, and thus in a manner transcends common life. In the Enquiry Hume tries to make it clearer by introducing the new distinctions.
Next question, then, will be about the relation between the transcendent form of scepticism and the mitigated scepticism, which is apparently a form of philosophy that is determinedly immanent to common life. Hume says that the mitigated scepticism is the result of the excessive scepticism. If, though, the excessive scepticism is the transcendent kind of scepticism, asserted from a point of view external to common life, how can it give rise to an internal point of view as its result? My answer is that the transcendent scepticism reveals that there is no rational ground for reliance on our cognitive faculties, and this makes the return to nature and common sense inevitable, since philosophy can not stand alone when it has extinguished all the evidence of the senses and reason. A similar move from an external to an internal point of view is found in Treatise I, iv, 7. Thus, The mitigated scepticism and the true philosophy Hume recommends at the end of the first Book of the Treatise are one and the same.
The excessively sceptical views transcend common life. This does not mean, though, that they are beyond the boundaries of the meaningful, in the sense in which some philosophers have believed what they call metaphysics is. The excessive and the mitigated scepticism are both meaningful forms of philosophy. Unlike Wittgenstein in the Tractatus and Logical Positivists, Hume does not dismiss transcendent philosophical questions as meaningless. This will be the last point I argue for in this paper.
Let us begin with the sceptical arguments against the evidence of the senses. When we compare the arguments on this subject in the Treatise and the Enquiry, what puzzles us most is the different treatments Hume gives to the double images and similar observations. In the Treatise Hume regards the argument derived from them as decisive against the ordinary people's supposition that perceptions are objects. (T210f.) In the Enquiry they are dismissed as 'trite topics' without any detailed treatment. (E151) This contrast is all the more perplexing because the first of the two 'profound arguments' which Hume regards as valid and cogent as opposed to the 'trite topics' follows the same pattern as the argument in the Treatise, which leads from the fact that what perceptually appears to us is relative to the situation to the conclusion that it is not identical with what really is, namely, the argument from relativity.
Though the arguments in the Treatise and the Enquiry follow the common pattern, there are differences. Since the argument in the Enquiry is shorter and simpler, it is natural to suppose that what Hume is dissatisfied with in the argument in the Treatise is part of what is included in it and disappears from the 'profound' argument in the Enquiry. One such element is the reference to 'our organs and the disposition of our nerves and animal spirits' and another is the reference to the 'common and natural position' of things in the visual field. (T211) Both of these two appear in the 'trite topics.' Thus, we can reasonably infer that Hume tries to get rid of these elements from what he supposes to be a valid argument against the evidence of the senses.
What, then, does Hume try to achieve by getting rid of them? I think what Hume wants to do is to free the sceptical argument from the supposition that there are fallacious and accurate perceptions.
In the trite topics, observations that indicate the dependence of appearances on situations are supposed to show the fallaciousness of those appearance, though logically speaking the dependence and the fallaciousness are independent from each other. (E151) It is usual to use cases of appearances in non-standard situations in order to show that appearances are dependent on situations. In such cases it is difficult to state the experiments apart from the supposition that the appearances referred to in them are fallacious. Thus, in the Treatise Hume says that appearances 'are removed from their common and natural position.' (T210) Being common and natural does not imply being closer to reality. These characteristics, though, are usually not distinguished, especially when we follow the manner of thinking and speaking of ordinary people, as Hume does in the Treatise. After this examination of the argument in the Treatise by comparison with the trite topics, it would be easy to remark that the first philosophical argument in the Enquiry is formulated with great care so that it should avoid referring to the fallaciousness of appearances and thus slipping into the way of speaking of ordinary people.
In spite of this difference, Hume's main points in his presentation of the sceptical arguments concerning the senses remain the same from the Treatise to the Enquiry. We can clearly see this when we turn our eye to the wider context in which the argument from double vision is put in the Treatise. There it works as a step in the transition from the opinion of common people to that of philosophers, namely, from the view that perceptions are objects to the denial of that identification. The argument from relativity is given as a reason for this transition. The separation of perceptions from objects, though, is earlier in the Treatise mentioned as a point taken for granted by philosophers, without any argument to support it and independently from common people's presupposition of there being among perceptions true ones and false ones. '[Philosophy] informs us that every thing which appears to the mind is nothing but a perception, and is interrupted and dependent on the mind; whereas the vulgar confound perceptions and objects.' (T193) This, along with the fact that the argument from relativity can be formulated without the presupposition, as is in the Enquiry, to lead to the same separation, shows that it is the nature of perceptions that distinguishes them from objects, rather than their occasional fallaciousness, that Hume intends as one of the main points of the sceptical arguments.
The other main point is that perceptions have no external model or archetype. The distinction of perceptions from objects as such is neutral between two theories of perception. One theory is representational realism or in the term Hume uses in the Treatise, the philosophical system. It says that perceptions are representations of objects that resemble and cause them, though distinct from them. The other theory is antirealism which says that there is nothing for perceptions to be representations of. In both the Treatise and the Enquiry the distinction of perceptions from objects is stated as if it gave a prima facie support for the first theory, and then that theory is refuted in favour of the second theory. (T210ff., E152ff.) The two books agree in further confirming antirealism by an argument that denies that primary qualities can be abstracted from secondary qualities. This is done in the second philosophical argument in the Enquiry. (T226ff., E154f.)
To summarize what I have said so far, the sceptical arguments concerning the senses are essentially the same in the Treatise and in the Enquiry, though the latter book put them in a neater, and in a manner purified form. The arguments in the Enquiry are purified in the sense that they are free from common people's presupposition derived from instinct. The instinctive presupposition is in the end inescapable, as Hume's own arguments show later in both of the two books. A philosopher, though, must be, even if for a while, free from it. Because philosophy consists, at least partially, in transcending common life and the manner of thinking necessitated by it. This transcendence, I believe, characterizes philosophy as the criticism of common life and it is what ultimately distinguish the philosophical arguments from the trite topics. In the case of scepticism concerning reason, again, the philosophical arguments are characterized by the same notion of transcendence, in contrast to the popular arguments. I will show this in the next section.
Unlike the case of sceptical arguments concerning the senses, the arguments against the evidence of reason seem totally different in the Treatise and in the Enquiry. In the Treatise Hume argues that the reflections on the fallibility of our reasoning in the past first reduce the certainty of abstract reasoning to probability. By repeating similar reflections, all kinds of probability, including that derived from weakening the evidence of abstract reasoning and the initial evidence of moral reasoning, are further diminished until we reach at a total extinction of belief and evidence. (T180ff.) In the Enquiry anything like this is not even mentioned in connection with abstract reasoning. In connection with moral reasoning, some considerations that suggest a line of argument similar to it are touched upon, but Hume regards them as but weak. They are called the 'popular' objections to moral evidence as opposed to the 'philosophical' objections that Hume regards as valid. (E158f.)
I understand that what characterizes the popular objections as opposed to the philosophical is the fact that it shares common people's instinctive presupposition about the validity of causal reasoning, since the reflections on past errors are a kind of causal reasoning. The philosophical objections on the other hand are made against the very instinctive inference derived from custom. (E159) I find here a complete parallelism between the distinction of the trite and the philosophical topics concerning the senses and that of the popular and the philosophical objections to moral reasoning. The defining characteristic of the philosophical objections is their being external to custom or common life.
Hume's caution against the instinctive presupposition thus leads him to the rejection of the argument from diminished evidence, which he has elaborated at length in Treatise, I, iv, 1. Again not unlike the case of the scepticism concerning the senses, though, the difference between the Treatise and the Enquiry should not be exaggerated. In the Treatise Hume says:
My intention then in displaying so carefully the arguments of that fantastic sect, is only to make the reader sensible of the truth of my hypothesis, that all our reasonings concerning causes and effects, are derived from nothing but custom; and that belief is more properly an act of the sensitive, than of the cogitative part of our natures. (T183)
The diminished evidence argument, then, is even in the Treatise given not as the main argument concerning the evidence of reason but as an additional point that confirms the main hypothesis that it is derived from nothing but custom. This is exactly the point of the philosophical objections in the Enquiry.
We have seen so far that in making the distinction in the Enquiry between the trite or popular arguments and the philosophical arguments, Hume tries to purify scepticism from instinctive, common-sensical presuppositions, and thus to make it transcend common life, though this attempt leaves the main body of Hume's arguments the same from the Treatise to the Enquiry. A natural question to ask now would be this: What, then, is the relation between Hume's preference for transcendent arguments on the one hand, and the support for the mitigated scepticism or academical philosophy, and thus for the immanence to common life on the other, with which Hume concludes the discussion of scepticism?
To this question the answer we can extract from Hume's text is that the mitigated scepticism is the result of the Pyrrhonism, or what we may call alternatively the transcendent scepticism. Hume distinguishes two species of mitigated scepticism. One is a reasonable degree of doubt derived from correcting the Pyrrhonian doubt by common sense and reflection. (E161) The other is 'the limitation of our enquiries to such subjects as are best adapted to the narrow capacity of human understanding.' (E162) In explaining how the Pyrrhonian doubt leads to the mitigated doubt, or the doubt within the limit of common sense, Hume talks of 'the strange infirmities of human understanding, even in its most perfect state,' etc. (E161) This may seem to be repeating the point of the popular objections, in which Hume refers to 'the natural weakness of the human understanding.' (E158) This, though, can not be the case. Because, first and obviously, Hume dismisses the popular objections, and it would be odd if he repeated the same point to justify the form of scepticism he recommends. Second, the popular objections refer to the variations in our opinions according to different situations in common life, while the infirmities of human understanding that leads to the useful doubt are found in the most accurate reasoning in sciences. Thus, the first species of mitigated scepticism is derived from the excessive scepticism in the same way as its second species, which Hume explains by saying, '[those who have a propensity to philosophy] will never be tempted to go beyond common life, so long as they consider the imperfection of those faculties which they employ, their narrow reach, and their inaccurate operations. While we cannot give a satisfactory reason, why we believe, after a thousand experiments, that a stone will fall, or fire burn; can we ever satisfy ourselves concerning any determination, which we may form, with regard to the origin of worlds, and the situation of nature, from, and to eternity?' (E162) Hume is making the same point here as in the philosophical objections to the evidence of reason, and I have already pointed out that the philosophical objections are made from a transcendent point of view. The transcendent scepticism reveals that there is no rational ground for reliance on our cognitive faculties, and this makes the return to nature and common sense inevitable, since philosophy can not stand alone when it has extinguished all the evidence of the senses and reason.
The same relation of the philosophy immanent to common life and the transcendent scepticism is found in Treatise I, vi, 7. First, the two books agree in their rejection of metaphysical speculations and advocacy of the limitation of philosophical inquiries to subjects that are suitable for human understanding. Thus Hume dismisses 'hypotheses embraced merely for being specious and agreeable,' because they prevent us from having 'any steady principles, nor any sentiments, which will suit with common practice and experience.' (T272) He also expresses his hope of 'pointing out to [philosophers] more distinctly those subjects where alone they can expect assurance and conviction,' and these subjects belong to 'Human Nature,' which he calls 'the only science of man.' (T273)
Second, also in the Treatise Hume presents his philosophy as the result of the transcendent scepticism, and indeed as more sceptical than it. That is, for him the true philosophy is the true scepticism.
The conduct of a man who studies philosophy in this careless manner, is more truly sceptical than that of one who, feeling in himself an inclination to it, is yet so overwhelmed with doubts and scruples, as totally to reject it. A true sceptic will be diffident of his philosophical doubts, as well as of his philosophical convictions; and will never refuse any innocent satisfaction which offers itself, upon account of either of them. (ibid.)
I believe that the foregoing argument has shown that the mitigated scepticism in the Enquiry and the science of man in the Treatise are identical in content, and that both are the result of the transcendent scepticism.
Karl Popper once remarked, 'Hume condemned his own Enquiry on its last page; just as later Wittgenstein condemned his own Tractatus on its last page.'* What he had in mind was Hume's last statements in the Enquiry, in which he urges us to throw into fire all books that do not contain any abstract reasoning concerning quantity or number, or any experimental reasoning concerning matter of fact and existence. (E165) Popper seems to have understood Hume as dismissing philosophical arguments in the Enquiry as meaningless, like Logical Positivists dismissed metaphysical questions, thinking that they were following Wittgenstein in doing so. Antony Flew rightly points out the unfairness of this comparison to Hume, by noting that in Hume's conception of the science of man, it includes the arguments in the Enquiry, as well as those in the Treatise.** I would like to conclude this paper by observing that not only Hume does not condemn his own academical philosophy, but also he does not condemn as nonsensical the excessive scepticism that paves the way for the mitigated scepticism.
* The Logic of Scientific Discovery, revised edition, Hutchinson, 1980, p. 35n.
** Hume's Philosophy of Belief, Routledge and Kegan Paul, 1961, p. 270.
In the Enquiry, in advocating the limitation of our enquiries, Hume condemns speculations concerning the origin or worlds etc. on the basis of the transcendent scepticism against moral reasoning. (E162) This means that the conclusion of sceptical arguments must be retained in the act of making what Popper would call 'demarcation' rather than being abandoned as meaningless. Hume regards sceptical principles as answers to meaningful questions, unlike Wittgenstein, according to whom '[scepticism] tries to raise doubts where no question can be asked.' *
* Tractatus Logico-Philosophicus, translated by D. F. Pears and B. F. McGuiness, Routledge and Kegan Paul, 1961, 6.51.
Certainly, Hume thinks that the transcendent scepticism cannot stand by itself and the true philosopher must go back to the realm of common life. This is not, though, because sceptical questions are meaningless, but because no philosophical principle can be steady without 'suit[ing] with common practice and experience.' (T272) For Hume philosophy is not the ladder to be thrown away after one has climbed up it, but must stay there as the necessary substructure on which the edifice of examined life stands. I believe we can understand in this light Hume's saying, 'philosophical decisions are nothing but the reflections of common life, methodized and corrected.' (E162)