From the same principles it may be collected that all such pompous theories of morals, however seemingly diversified, yet amount ultimately to the same thing, being all built upon the same false bottom of innate notions; and from the history of this science we may see that they have received no manner of improvement (as indeed by the supposition of their innateness they become incapable of any) from the days of Plato to our own; but must always take the main point, the ground of obligation, for granted: which is in truth the shortest and safest way of proceeding for such self-taught philosophers, and saves a deal of trouble in seeking reasons for what they advance, where none are to be found. Mr. Locke went a far different way to work, at the very entrance on his Essay, pointing out the true origin of all our passions and affections, i. e. sensitive pleasure and pain; and accordingly directing us to the proper principle and end of virtue, private happiness, in each individual; as well as laying down the adequate rule and only solid ground of moral obligation, the divine will. From whence also it may well be concluded that moral propositions are equally capable of certainty, and that such certainty is equally reducible to strict demonstration here as in other sciences, since they consist of the very same kind of ideas [viz. general abstract ones, the true and only ground of all general knowledge]: provided always that the terms be once clearly settled, in which lies the chief difficulty, and are constantly applied (as surely they may be) with equal steadiness and precision: which was undoubtedly Mr. Locke’s meaning in that assertion of his which drew upon him so many solicitations to set about such a systematic demonstration of morals.
The Essay on Human Understanding, that most distinguished of all his works, is to be considered as a system, at its first appearance absolutely new, and directly opposite to the notions and persuasions then established in the world. Now as it seldom happens that the person who first suggests a discovery in any science is at the same time solicitous, or perhaps qualified to lay open all the consequences that follow from it; in such a work much of course is left to the reader, who must carefully apply the leading principles to many cases and conclusions not there specified. To what else but a neglect of this application shall we impute it that there are still numbers amongst us who profess to pay the greatest deference to Mr. Locke, and to be well acquainted with his writings, and would perhaps take it ill to have this pretension questioned; yet appear either wholly unable, or unaccustomed, to draw the natural consequence from any one of his principal positions? Why, for instance, do we still continue so unsettled in the first principles and foundation of morals? How came we not to perceive that by the very same arguments which that great author used with so much success in extirpating innate ideas, he most effectually eradicated all innate or connate senses, instincts, &c. by not only leading us to conclude that every such sense must, in the very nature of it, imply an object correspondent to and of the same standing with itself, to which it refers [as each relative implies its correlate], the real existence of which object he has confuted in every shape; but also by showing that for each moral proposition men actually want and may demand a reason or proof deduced from another science, and founded on natural good and evil: and consequently where no such reason can be assigned, these same senses or instincts, with whatever titles decorated, whether styled sympathetic or sentimental, common or intuitive,—ought to be looked upon as no more than mere habits; under which familiar name their authority is soon discovered, and their effects accounted for.
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