The Principles of Moral and Christian Philosophy. George Turnbull

must, in innumerable cases, act upon probable evidence, is a fact too evident to need any proof; and that acting upon probable evidence, is acting upon presumptions founded upon analogy or likeness, will likewise be readily acknowledged by all who will allow themselves to consider what probability means. That which chiefly constitutes it, is expressed in the word likely; that is,^a like some known truth or true event; like, in itself, in its evidence, in some more or fewer of its circumstances. Now, it belongs to the subject of logick to enquire into the nature, the foundation and measure of probability, or to reduce the extent, compass or force of analogical reasoning, to general observations and rules; and thus to guard against the errors to which reasoning from analogy is liable; but if we enquire from whence it proceeds, that likeness should beget that presumption, opinion, or full conviction, which the human mind is formed to receive from it; and which it does necessarily produce in every one proportionally to its various degrees. This question contains its own proper and full answer. It is because the mind is formed to receive satisfaction from it, and acquiesce in it proportionally to its several degrees. And the final cause of this formation is no less evident; since our present state makes our acting upon such evidence<42> necessary. When demonstration is said to force our assent, the meaning is, that by it, we have a clear perception of the necessary agreement or disagreement of certain ideas; an agreement or disagreement that cannot but take place. But where such a necessary agreement or disagreement of ideas cannot be perceived, as it cannot be with respect to any connexions of nature of positive institution, of which sort are, for instance, the connexion between the ideas of sight and touch, and almost all, if not all the connexions of the sensible world. In such cases, nothing but various degrees of likelihood or unlikelihood can be perceived; and such perceptions do not so properly operate upon our understanding producing assent, as upon our temper producing satisfaction and complacency; the contraries of which are wavering and mistrust, or dissidence. But not to seem to dispute about words, let the effect of probability, that is, of likeness, be called an effect upon the understanding, or upon the will; a judgment or a tendency to determine ourselves to act this or the other way, or not to act at all, according to the various force of presumption; yet the effect of it upon the mind cannot be ultimately accounted for, without supposing an aptitude or disposition in our natures to be influenced by presumptions or appearances of likeness. ’Tis the same here, as with regard to the perception of beauty; when we have analysed it into its constituent and concomitant parts; we have in that case a clearer and more adequate notion of it; yet it must still remain true with respect to it, that its constituent and concomitant parts make a perception that affects the mind in a certain manner, merely because the mind is intended and fitted by nature to be so affected by it. We must in all such cases at last come to an ultimate reason, which can be no other than the adjustment of the mind to certain objects. But so far as we see and find our minds suited to our state and circumstances;<43> so far do we see clear proofs of wisdom and goodness in our make and contrivance, or of care and concern about our welfare. ’Tis almost unnecessary to remark here, that to say, the mind often presumes rashly, and makes false judgments about probability, is no more any objection against its right formation in our circumstances with respect to its natural aptitude to be influenced by probability, than it is against certainty and scientific evidence, wherever that is attainable, to say many philosophers have been deceived, and have mistaken absurdities for demonstrations.

      Fifth instance.

      V. The care of nature about us, with respect to knowledge, appears by its giving us considerable light into some more necessary parts of knowledge; or, at least, considerable hints and helps for discovering several useful arts, by the operations and productions of inferior animals directed by their natural instincts. For these acting as nature impels them, shew some of us how to build, others to swim, others to dive and fish, some how to spin and weave, some how to cure wounds and diseases, others how to modulate the voice into melody, &c.

      This truth is charmingly represented by an excellent poet, in a poem (that must be highly valued while moral science and true harmony are relished in the world) which I shall have frequent occasion to quote.

      See him from nature rising slow to art!

      To copy instinct then was reason’s part;

       Thus then to man the voice of nature spake—

       “Go! from the creatures thy instructions take;

       Learn from the birds what food the thickets yield;

      Learn from the beasts the physic of the field:<44>

      Thy arts of building from the bee receive;

      Learn of the mole to plow, the worm to weave;

      Learn from the little nautilus to sail,

       Spread the thin oar and catch the driving gale.

       Here too all forms of social union find,

       And hence let reason, late instruct mankind:

       Here subterranean works and cities see,

       The towns aerial on the waving tree.

       Learn each small people’s genius, policies;

       The ants republic, and the realm of bees;

       How those in common all their stores bestow,

       And anarchy without confusion know,

       And these for ever, tho’ a monarch reign,

       Their sep’rate cells and properties maintain.

       Mark what unvary’d laws preserve their state,

       Laws wise as nature, and as fix’d as fate,

       In vain thy reason finer webs shall draw,

       Entangle justice in her net of law.

       And right too rigid, harden into wrong,

       Still for the strong too weak, the weak too strong.

       Yet go! and thus o’er all the creatures sway,

       Thus let the wiser make the rest obey,

       And for those arts mere instinct could afford,

       Be crown’d as monarchs, or as gods ador’d.

      Essay on man, epist. III.^a

      Sixth instance.

      VI. Add to this, that as it is from nature only that the real knowledge of nature can be learned, so the connexions of nature lie open to our view.^b It is only because men have wilfully shut their eyes against<45> nature, and have vainly set themselves to devise or guess its methods of operation, without taking any assistance from nature it self, that natural knowledge has made such slow advances. Whence it comes about that men have at any time been misled into the foolish attempt of understanding nature by any other method, than by attending to it, and carefully observing it, is a question I shall not now enter upon. But so obvious are the greater part of nature’s connexions to all those who study nature, that so soon as the right, the only method of getting into its secrets was pursued, great improvements were quickly made in that knowledge; and all discoveries in it, after they are found out, appear so simple and so obvious, that one cannot help wondering how it came about that they were not sooner seen and observed.

      Now nature, in order to put us into the right way of coming at real knowledge, has not only implanted in our minds an eager desire or thirst after knowledge, but likewise a strong disposition to emulate all the works of nature that fall more immediately under our cognisance, and in a manner to vie with nature in productions of our own. This disposition to emulate nature, as it adds considerable force to our desire of knowledge, so it serves to assist us in acquiring it; for it necessarily