Now when Hume goes on to consider more closely what is subsumed under experience, he finds categories of the understanding present there, and more especially the determination of the universal and of universal necessity; he took under his consideration more particularly the category of cause and effect, and in it set forth the rational element, inasmuch as in this causal relationship necessity is especially contained. Here Hume really completed the system of Locke, since he consistently drew attention to the fact that if this point of view be adhered to, experience is indeed the principle of whatever one knows, or perception itself contains everything that happens, but nevertheless the determination of universality and necessity are not contained in, nor were they given us by experience. Hume has thus destroyed the objectivity or absolute nature of thought-determinations. “Our conviction of the truth of a fact rests on feeling, memory, and the reasonings founded on the causal connection, i.e. on the relation of cause and effect. The knowledge of this relation is not attained by reasonings a priori, but arises entirely from experience; and we draw inferences, since we expect similar results to follow from similar causes, by reason of the principle of the custom or habit of conjoining different manifestations, i.e. by reason of the principle of the association of ideas. Hence there is no knowledge and no metaphysics beyond experience.”[291]
The simple thought we have here is exactly what Locke says, that we must receive the conception of cause and effect, and thus of a necessary connection, from experience; but experience, as sensuous perception, contains no necessity, has no causal connection. For in what we term such, that which we properly speaking perceive is merely the fact that something first of all happens and that then something else follows. Immediate perception relates only to a content of conditions or things which are present alongside of and in succession to one another, but not to what we call cause and effect; in time-succession there is thus no relation of cause and effect, and consequently no necessity either.[292] When we say the pressure of the water is the cause of the destruction of this house, that is no pure experience. We have merely seen the water pressing or moving along in this direction, and subsequently the house falling down; and so with other examples. Necessity is thus not justified by experience, but we carry it into experience; it is accidentally arrived at by us and is subjective merely. This kind of universality which we connect with necessity, Hume calls custom. Because we have often seen results to follow we are accustomed to regard the connection as a necessary one; the necessity to him is thus a quite contingent association of ideas, which is custom.
It is the same thing in respect of the universal. What we perceive are individual phenomena and sensations in which we see that this is now one thing and now another. It may likewise be that we perceive the same determination frequently repeated and in manifold ways. But this is still far removed from universality; universality is a determination which is not given to us through experience. It may be said that this is quite a correct remark on Hume’s part, if by experience we understand outward experience. Experience is sensible that something exists, but nevertheless the universal is not as yet present in it. Indeed, sensuous existence as such is something which is set forth as indifferent, not differentiated from anything else; but sensuous existence is likewise universal in itself, or the indifference of its determinateness is not its only determinateness. But since Hume regards necessity, the unity of opposites, as resting quite subjectively on custom, we cannot get any deeper in thought. Custom is indeed so far a necessity in consciousness, and to this extent we really see the principle of this idealism in it; but in the second place this necessity is represented as something quite devoid of thought or Notion.
This custom obtains both in our perception which relates to sensuous nature, and in relation to law and morality. The ideas of justice and morality rest upon an instinct, on a subjective, but very often deceptive moral feeling.[293] From a sceptical point of view the opposite may likewise be demonstrated. From this side Hume considers justice, morality, religious determinations, and disputes their absolute validity. That is to say when it is assumed that our knowledge arises from experience, and that we must consider only what we obtain thereby to be the truth, we find indeed in our feeling, the sentiment e.g. that the murderer, the thief, &c., must be punished; and because this is likewise felt by others it is universally allowed. But Hume, like the sceptics of former days, appeals to the various opinions of various nations: amongst different nations and in different times various standards of right have been held.[294] There are those who in this case do not have the feeling of wrong-doing in respect of stealing, e.g. the Lacedæmonians or the so-called innocent inhabitants of the South Sea Islands. What is by one nation called immoral, shameful and irreligious, is by another not considered so at all. Thus because such matters rest upon experience, one subject has such and such an experience, finds, for instance, in his religious feelings this determination which inclines him to God, while another subject has different experiences altogether. We are in the habit of allowing one thing to be just and moral, others have another mode of regarding it. Hence if the truth depends upon experience, the element of universality, of objectivity, &c., comes from elsewhere, or is not justified by experience. Hume thus declared this sort of universality, as he declared necessity, to be rather subjectively than objectively existent; for custom is just a subjective universality of this kind. This is an important and acute observation in relation to experience looked at as the source of knowledge; and it is from this point that the Kantian reflection now begins.
Hume (Essays and Treatises on several subjects, Vol. III. Sect. 8, 11) then extended his scepticism to the conceptions and doctrines of freedom and necessity, and to the proofs of the existence of God; and in fact scepticism here possesses a wide field. To such a system of reasoning from thoughts and possibilities another method of reasoning may again be opposed, and this reasoning is no better than the other. What is said to be metaphysically established regarding immortality, God, nature, &c., lacks a real ground for resting upon, such as is professed to be given; for the inferences on which men ground their proofs are subjectively formed conceptions. But where a universality is found, it does not rest in the matter in itself, but is simply a subjective necessity which is really mere custom. Hence the result which Hume arrives at is necessarily astonishment regarding the condition of human knowledge, a general state of mistrust, and a sceptical indecision—which indeed does not amount to much. The condition of human knowledge regarding which Hume so much wonders, he further describes as containing an antagonism between reason and instinct; this instinct, it is said, which embraces many sorts of powers, inclinations, &c., deceives us in many different ways, and reason demonstrates this. But on the other side it is empty, without content or principles of its own; and if a content is in question at all, it must keep to those inclinations. In itself reason thus has no criterion whereby the antagonism between individual desires, and between itself and the desires, may be settled.[295] Thus everything appears in the form of an irrational existence devoid of thought; the implicitly true and right is not in thought, but in the form of an instinct, a desire.
[B. Scottish Philosophy.]
In Scotland quite another school of thought developed, and the Scotch are the foremost of Hume’s opponents; in German philosophy, on the other hand, we have to recognize in Kant another opposing force to that of Hume. To the Scottish school many philosophers belong; English philosophy is now restricted to Edinburgh and Glasgow, in which places a number of professors belonging to this school succeeded one another. To the scepticism of Hume they oppose an inward independent source of truth for all that pertains to religion and morality. This coincides with Kant, who also maintains an inward source or spring as against external perception; but in the case of Kant this has quite another form than that which it possesses with the Scottish philosophers. To them this inward independent source is not thought or reason as such, for the content which comes to pass from this inwardness is concrete in its nature, and likewise demands for itself the external matter of experience. It consists of popular principles, which on the one hand are opposed to the externality of the sources of knowledge, and, on the other, to metaphysics as such, to abstract thought or reasoning on its own account. This sort of reasoning understanding applied itself to ethics and to politics—sciences which have been much developed by German, French, and above all by Scottish philosophers (supra, p. 320): they regarded morality as cultured men would, and sought to bring moral duties under a principle. Many of their works are translated into German; several of these on ethics or morality are translated by Garve, for instance, who also translated Cicero De Officiis, and they are written in a manner similar to that of Cicero when he uses the expression Insitum est a natura (Vol. I. p. 93). This moral sentiment and the ordinary human understanding hereafter formed the common principle to a whole succession of Scots, such as Thomas Reid, Beattie, Oswald, and others; in this way they frequently made sagacious observations, but with them speculative philosophy quite disappears. One special characteristic of these Scottish philosophers is that they have sought accurately to define the principle of knowledge; but on the whole they start from the same point as that which was in Germany likewise accepted as the principle. That is to say they represented the so-called healthy reason, or common-sense (sensus communis), as the ground of truth. The following are the principal members of this school, each of whom has some special feature distinguishing him from the rest.
[1. Thomas Reid.]
Thomas Reid, born in 1710, died as a professor in Glasgow in 1796.[296] He maintained the principle of common-sense. His endeavour was to discover the principles of knowledge, and the following are his conclusions: “(a) There are certain undemonstrated and undemonstrable fundamental truths which common-sense begets and recognizes as immediately conclusive and absolute.” This hence constitutes an immediate knowledge; in it an inward independent source is set forth which is hereby opposed to religion as revealed. “(b) These immediate truths require no support from any elaborated science, nor do they submit to its criticism;” they cannot be criticized by philosophy. “(c) Philosophy itself has no root other than that of an immediate, self-enlightening truth; whatever contradicts such truth is in itself false, contradictory, and absurd.” This is true for knowledge and “(d) Morality; the individual is moral if he acts in accordance with the perfect principles of the perfection of the whole and with his own duty as it is known to him.”[297]