the knowledge imparted by the senses in common.This continued, for long, to be one of the meanings of the phrase in philosophy; but by Reid's time it was thus known only to scholars.In the use which Reid makes of it, there is a fatal ambiguity.It is employed to signify two very different things.It denotes that combination of qualities which constitutes <good sense>, being, according to an old saying, the most uncommon of all the senses.This valuable property is not common to all men, but is possessed only by a certain number; and there are others who can never acquire it, and it is always the result of a number of gifts and attainments, such as an originally sound judgment and a careful observation of mankind and the world.In this signification common sense is not to be the final appeal in philosophy, science, or any other department of investigation; though in all it may keep us from much error.
Practical sense, as it claimed to be, long opposed the doctrine of there being an antipodes and of the earth moving; it spoke contemptuously in the first instance of some of the greatest achievements of our world, the deeds {222} of philanthropists, and the sufferings of martyrs; it laughed at the early poetry of Wordsworth and Tennyson.All that good sense can do in science and philosophy is to guard us against accepting any doctrine till it is settled by inductive proof.
But the phrase has another and a different signification in the philosophical works, including Reid's, of last century.It denotes the aggregate of original principles planted in the minds of all, and in ordinary circumstances operating in the minds of all.It is only in this last sense that it can be legitimately employed in overthrowing scepticism, or for any philosophic purpose.
Reid seeks to take advantage of both these meanings.He would show that the views he opposes, though supported by men of high intellectual power,-such as Locke, Berkeley, and Hume, -- have the good sense of mankind against them.It can easily be shown that he employs the phrase once and again to designate sound practical judgment.He describes Newton's "Regulae Philosophandi" as " maxims of common sense." (P.
97.) He is constantly opposing common sense to reason and philosophy; whereas he admits elsewhere, using the phrase in the other sense that " philosophy has no other root but the principles of common sense." (p.101.) This dexterous attempt to combine the two meanings, while perhaps contributing to the immediate popularity of Reid, and still more of Beattie, turned in the end against them (in the use of a two-edged sword, one edge is apt to wound him who uses it) in the estimation of philosophic thinkers, who, looking on the appeal as only to vulgar judgment, which may be prejudice, have denied the validity of the argument.
Hamilton has succeeded, so I think, in showing that the argument as employed by Reid is valid in itself, and legitimately used against scepticism.His appeal is to principles in our constitution which all are obliged to admit and act upon.But an appeal in a loose way to a sense supposed to be in all men may be very illusive.In order to its philosophical application, it must be shown that the principle is in all men as a necessary principle; and this Reid has commonly done, though there are cases, we have seen, in which he admits first principles too readily.But he should have done more: it is only when we have carefully ascertained the precise nature of the original perception, and expressed it in a law, that we are entitled {223} to employ it in constructing a philosophy or in opposing scepticism.As long as it is a mere loose appeal to an undetermined principle, the argument may be very illusive.
At this point Reid has often failed, owing to a deficiency of logical power.What he calls in is commonly a genuine mental principle; but, owing to his not furnishing a rigid account of its nature and its laws, we may be in doubt whether the application which he makes of it is legitimate.
The important work of Reid needs to be supplemented by an investigation, conducted in his own careful manner, of the precise nature of the principles of common sense, of their points of agreement and of difference, of their precise laws and varied modes of action.
It is not easy to determine to what the appeal is ultimately to be in the philosophy of Reid.It is to common sense: but in what signification? Because it is a sense? Or because it is so constituted as to discern objects and truth? Or because it is common to all men? Or because we must trust to it whether we will or no? It is not easy to ascertain what would be Reid's, or even Hamilton's, answers to these questions.There are frequent passages in which Reid's appeal seems to be to the constitution of our minds (Hamilton's ultimate test, like Kant's, seems to be necessity); for he says, we " cannot have a better reason for trusting consciousness, than that every man, while his mind is sound, is determined by the constitution of his nature, to give implicit belief to it." But some one may ask, Why should we trust our constitution? May not our constitution, common or individual, deceive us? Has Hume succeeded in showing that our constitution followed out in different ways leads to contradictions? To such questions Reid would have little else to say than that we <must>
