excellent introduction to Hume is P. Millican’s General Philosophy lecture from 2010 http://podcasts.ox.ac.uk/26-david-hume recorded for Oxford University, and also his subsequent series of podcast lectures on ‘David Hume and the first book of his Treatise of Human Nature’ (2012), http://podcasts.ox.ac.uk/series/introduction-david-humes-treatise-human-nature-book-one. See also D. Robinson’s Oxford lecture on Hume and causation from the lecture series ‘Reid’s Critique of Hume’ (2014), http://podcasts.ox.ac.uk/hume-causation.5 You may also want to listen to a stimulating episode of the BBC program In Our Time presented by M. Bragg at https://www.bbc.co.uk/programmes/b015cpfp.
Notes
* David Hume, An Enquiry Concerning Human Understanding [1748]. Extracts from Section IV, part 1, and Section XII, part 3; with some changes of spelling and punctuation. There are many editions, including that by Tom L. Beauchamp (Oxford: Oxford University Press, 1999), which contains a useful introduction for students.
1 1 Treatise, Bk I, part iv, section 3, para. 7.
2 2 Ibid., para. 2.
3 3 Hume argues elsewhere that our tendency to generalize on the basis of limited experience is based more on custom and habit than on any sound reasoning: see below, Part VII, extract 5 and extract 6.
4 4 For more on why Hume maintains this, see Part VII, extract 6.
5 5 Hume means the abstract mathematical sciences whose truths are capable of rigorous demonstration.
8 Metaphysics, Old and New: Immanuel Kant, Prolegomena*
Hume’s challenge to speculative metaphysics exerted a strong influence on subsequent philosophy, and was taken up in a systematic way by the famous German philosopher Immanuel Kant, first in his mammoth and highly complex Critique of Pure Reason (1781), and then in the Prolegomena (1783), which was intended as a more popular abstract of that work. The full title of the ‘Prolegomena’ (‘Preamble’ or ‘Preliminary Remarks’) is Prolegomena to any future metaphysics which will be able to present itself as a science (Prolegomena zu einer jeden künftigen Metaphysik die als Wissenschaft wird auftreten können); the question Kant addresses is ‘whether such a thing as metaphysics is even possible at all’.
Hume had convinced Kant that previous attempts to ascend beyond the empirical world and describe the supposed ultimate nature of reality (e.g. the theory of substance proposed by Leibniz (see above, extract 5)) were doomed to failure. Kant condemned such vain aspirations in a famous metaphor: ‘the light dove, cleaving the air in her free flight, might imagine [absurdly] that flight would be easier still in empty space’.1 There is, for Kant, no possible description of the world which can free itself from some reference to experience. But Kant argues that in experiencing the world, the mind is already armed with certain fundamental categories of understanding; these are a priori, but not in the traditional sense of being wholly abstract and independent of experience; rather they constitute the preconditions for all possible experience (see above, Part I, extract 8).
In the following set of extracts Kant argues that we do already possess knowledge that is both a priori and also genuinely informative or synthetic.2 To begin with, he argues that a priori mathematical judgements (e.g. that 7 + 5 = 12) are synthetic, since we cannot arrive at the concept of twelve merely by reflection on the notions of seven and five.3 Second, and more important, he takes up Hume’s challenge with respect to scientific knowledge (Hume had argued, extract 7 above, that we can never know any causal connections a priori). For Kant, the principle that every event has a cause is synthetic; yet it is a priori in the sense of being presupposed by experience (Kant argues elsewhere that we could not even begin to classify sets of perceptions as constituting genuine events unless the mind had the power to interpret the world in terms of causal frameworks).4
So there is, after all, room for a genuine metaphysics – not one which fruitlessly attempts to speculate about what lies beyond experience, but one which instead analyses and systematically lays out all the a priori concepts of the understanding which the mind necessarily employs in processing and interpreting the data of experience (see penultimate paragraph of extracts below). Though Kant does from time to time talk of a hidden world beyond experience, a world of what he calls noumena or ‘Things in Themselves’, he makes it clear that there can be no valid philosophical speculation about what such an independent reality might be like; human reason, when it operates properly, is necessarily confined to phenomena – to the world as experienced. The confusions and pretensions of traditional metaphysics arose from its attempt to describe the supposed nature of reality ‘in itself’; the new ‘critical’ metaphysics, mapping out the necessary preconditions for human experience, can hope to provide instead ‘definite and perfect knowledge’. It has, Kant concludes, the kind of validity and authority which modern astronomy has when compared to the pretensions of fortune-telling or astrology.
The distinction between analytic and synthetic judgements.
Metaphysical knowledge must contain simply judgements a priori; so much is demanded by the speciality of its sources. But judgements, let them have what origin they may, or let them even as regards logical form be constituted as they may, possess a distinction according to their content, by virtue of which they are either simply explanatory and contribute nothing to the content of a cognition, or they are extensive, and enlarge the given cognition; the first may be termed analytic, and the second synthetic judgements.
Analytic judgements say nothing in the predicate but what was already thought in the conception of the subject, though perhaps not so clearly, or with the same degree of consciousness. When I say, all bodies are extended, I do not thereby enlarge my conception of a body in the least, but simply analyse it, inasmuch as extension, although not expressly stated, was already thought in that conception; the judgement is, in other words, analytic. On the other hand, the proposition ‘some bodies are heavy’ contains something in the predicate which was not already thought in the general conception of a body; it enlarges, that is to say, my knowledge, in so far as it adds something to my conception; and must therefore be termed a synthetic judgement.
The common principle of all analytic judgements is the principle of contradiction.
All analytic judgements are based entirely on the principle of contradiction, and are by their nature cognitions a priori, whether the conceptions serving as their matter be empirical or not. For inasmuch as the predicate of an affirmative analytic judgement is previously thought in the conception of the subject, it cannot without contradiction be denied of it; in the same way, its contrary, in a negative analytic judgement, must necessarily be denied of the subject, likewise in accordance with the principle of contradiction. It is thus with the propositions ‘every body is extended’; ‘no body is unextended’. For this reason all analytic propositions are judgements a priori, although their conceptions may be empirical. Let us take as an instance the proposition ‘gold is a yellow metal’. Now, to know this, I require no further experience beyond my conception of gold, which contains the propositions that this body is yellow and a metal, for this constitutes precisely my conception, and therefore I have only to dissect it,
