CHAP. III. SECTION V. HUME (1711-1776). § 60. David Hume was the natural successor in philosophy of Locke and Berkeley, and he carried their principles to a logical conclusion. The same clearness and acuteness of analytic power which we observed in Berkeley are to be found in perhaps a still greater degree in Hume. The publication of his writings constituted a crisis in modern philosophy, which led his successors to go back to the consideration of the premises from which modern philosophers started, in order that they might avoid his conclu- Hume's sions. We shall give in his own words his most important doctrines. "All the perceptions of the human mind resolve themselves into two distinct kinds, which I shall call impressions and ideas. The difference betwixt these consists in the degrees of force and liveliness with which they strike upon the mind, and make their way into our thought or consciousness. Those perceptions which enter with most force and violence, we may name impressions; and, under this name, I comprehend all our sensations, passions and emotions, as they make their first appearance in the soul. By ideas, I mean the faint images of these in thinking and reasoning." "There is another division of our perceptions, *Treatise of Human Nature,' bk I., part I., § 1. doctrines. Impres ideas. sions and CHAP. III. SECT. V. Simple and complex perception. Character and relations of impressions and ideas. which it will be convenient to observe, and which extends itself both to our impressions and ideas. This division is into simple and complex. Simple perceptions, or impressions and ideas, are such as admit of no distinction or separation. The complex are the contrary to these, and may be distinguished into parts. Though a particular colour, taste, and smell, are qualities all united together in this apple, it is easy to perceive they are not the same, but are at least distinguishable from each other." * "All our simple ideas in their first appearance are derived from simple impressions which are correspondent to them, and which they exactly represent." † causes. "Impressions may be divided into two kinds, those of sensation and those of reflection. The first kind arises on the soul originally, from unknown The second is derived, in a great measure, from our ideas, and that in the following order. An impression first strikes upon the senses, and makes us perceive heat or cold, thirst or hunger, pleasure or pain, of some kind or other. Of this impression there is a copy taken by the mind, which remains after the impression ceases; and this we call an idea. This idea of pleasure or pain, when it returns upon the soul, produces the new impressions of desire and aversion, hope and fear, which may properly be called impressions of reflection, because derived from it. These again are copied by the memory and imagination and becomes ideas. "+ * Treatise,' bk. I., part I., § 1. † Ib. With reference to the substratum of bodies, Hume asks "whether the idea of substance be derived from the impressions of sensation or reflection? If it be conveyed to us by our senses, I ask, which of them, and after what manner? If it be perceived by the eyes, it must be a colour; if by the ears, a sound; if by the palate, a taste, and so of the other senses. But I believe none will assert that substance is either a colour, a sound, or a taste. The idea of substance must, therefore, be derived from an impression of reflection, if it really exist. But the impressions of reflection resolve themselves into our passions and emotions; none of which can possibly represent a substance. We have, therefore, no idea of substance distinct from that of a collection of particular qualities, nor have we any other meaning when we either talk or reason concerning it. The idea of a substance, as well as that of a mode, is nothing but a collection of simple ideas, that are united by the imagination and have a particular name assigned them, by which we are able to recall, either to ourselves or others, that collection. the difference betwixt these ideas consists in this, that the particular qualities which form a substance are commonly referred to an unknown something, in which they are supposed to inhere; or granting this fiction should not take place, are at least supposed to be closely and inseparably connected by the relations of contiguity and causation.” * But CHAP. III. SECT. V. Substance, what, "Upon opening my eyes and turning them to the Extension. *Treatise,' bk. I., part I., § 6. SECT. V. CHAP. III. surrounding objects, I perceive many visible bodies; and upon shutting them again, and considering the distance betwixt these bodies, I acquire the idea of extension. As every idea is derived from some impression which is exactly similar to it, the impressions similar to this idea of extension must either be some sensations derived from the sight, or some internal impressions arising from these sensations.”* It is not the latter, therefore it must be the former. "My senses convey to me only the impressions of coloured points, disposed in a certain manner. Hence we may conclude with certainty that the idea of extension is nothing but a copy of these coloured points and of the manner of their appearance." † Time. Space. Thus Hume concludes that extension is an idea abstracted from particular impressions of sense, the peculiarities of colour, &c., being left out of view, and attention paid only to the disposition of points. "As it is from the disposition of visible and tangible objects we receive the idea of space, so from the succession of ideas and impressions we form the idea of time; nor is it possible for time alone ever to make its appearance, or be taken notice of by the mind.” ‡ "We have no idea of space or extension but when we regard it is an object of our sight or feeling." So "the indivisible movements of time must be filled with some real object or existence, whose succession forms the duration, and makes it to be conceivable by the mind."§ * Treatise.' bk. I., part II., § 3. † Ib. ‡ Ib. § Ib. SECT. V. Cause of phenomena explic "As to those impressions, which arise from the CHAP. III. senses, their ultimate cause is, in my opinion, perfectly inexplicable by human reason, and it will always be impossible to decide with certainty, whether they arise immediately from the object, or are produced by the creative power of the mind, or are derived from the Author of our being.' able. "The opinion of the continued existence of body Objectivity depends on the coherence and constancy of certain explained. impressions."† § 61. Having given the important psychological doctrines of Hume in his own language, we now proceed to make such remarks upon them as seem called for. But, before doing so, we shall arrange more systematically the doctrines to which we propose to refer. (1.) All our simple ideas are copies of some impressions previously experienced. No idea, therefore, can be found in the mind which has not, more or less proximately, been copied from some impression. (2.) There is no idea in the mind of substance, either corporeal or spiritual, except in so far as substance means a collection of qualities or of impressions and ideas. This doctrine follows immediately from the preceding, since substance is admitted to be neither a sensation nor the copy of a sensation. (3.) Extension and duration, or space and time, are ideas abstracted from sensations. The idea of extension is a copy of the co-existent points of visible or tactual impressions. The idea of duration is a * Treatise,' bk. I., part III., § 5. † Treatise,' bk. I. part IV. § 2. Doctrines arranged. |