He reviews the famous argument of Descartes, " We think, therefore we are." "Nothing more certain: for the Ego or I being established in the first part of the proposition, the Ergo, no doubt, must hold it good in the latter." "For my own part," he adds, "I take my being upon trust" He everywhere appeals to the "Sensus Communis," or Common Sense.His general doctrine is thus expressed: "Some moral and philosophical truths there are withal so evident in themselves, that it would be easier to imagine half mankind to have run mad, and joined precisely in one and the same species of folly, than to admit any thing as truth which should be advanced against such <natural knowledge, fundamental reason, and common sense>." He allows that what is natural to us may require labor and pains to bring it out." Whatever materials or principles of this kind we may possibly bring with us, whatever good faculties, senses, or anticipating sensations and imaginations may be of nature's growth, and arise properly of themselves without our art, promotion, or assistance, the general <idea> which is formed of all this management, and the clear notion we attain of what is preferable and principal in all these subjects of choice and estimation, will not, as I imagine, by any person be taken for {32} <innate>.Use, practice, and culture must precede the under standing and wit of such an advanced size and growth as this." These surely are the very views which were developed more fully and articulately by Reid, in his opposition to the scepticism of Hume.The object of his works is to carry out these principles to taste and morals."Nor do I ask more when I undertake to prove the reality of virtue and morals.If I be certain that I am, it is certain and demonstrable who and what I should be." Should one who had the countenance of a gentleman ask me why I would avoid being nasty when nobody was present?'
in the first place, I should be fully satisfied that he himself was a very nasty gentleman who could ask this question, and that it would be a hard matter for me to make him ever conceive what true cleanliness was.However, Imight, notwithstanding this, be contented to give him a slight answer, and say, I It was because I had a nose.'
Should he trouble me further, and ask again, 'What if I had a cold? or what if naturally I had no such nice smell?' Imight answer perhaps, 'That I cared as little to see myself nasty as that others should see me in that condition.' I But what if it were in the dark?' 'Why, even then, though I had neither nose nor eyes, my <sense> of the matter would still be the same: my nature would rise at the thought of what was sordid."' He thus reaches a sense of beauty."Much in the same manner have I heard it asked, 'Why should a man be honest in the dark?"' The answer to this question brings him to a moral sense.
He speaks of nature in general, and human nature in particular, as an " economy," and as having a "constitution"and a "frame." In examining the nature of the soul, he finds (1) self-affections, which lead only to " the good of the private." He enumerates, as belonging to this class, ,love of life, resentment of injury, pleasure, or appetite towards nourishment and the means of generation; interest, or the desire of those conveniences by which we are well provided for or maintained; emulation, or love of praise and honor;indolence, or love of ease and rest." But he finds also (2)natural affections, which lead to the good of the public.He takes great pains to establish the existence of disinterested affections, and opposes the views of those who, like Rochefoucauld, would resolve all human action {33}