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berless classes of beings rising one above another by differences scarce perceptible, and leaving no where a single gap or interval : and from conviction of the uniformity of nature we infer, that the line is not broken off here, but is carried on in other worlds, till it end in the Deity. I proceed to another example. Every man is conscious of a self-motive power in himself; and from the uniformity of nature, we infer the same power in every one of our own species. The argument here from analogy carries great weight, because we entertain no doubt of the uniformity of nature with respect to beings of our own kind. We apply the same argument to other animals; tho' their resemblance to man appears not so certain, as that of one man to another. But why not also apply the same argument to infer a felf-motive power in matter? When we fee matter in motion without an external mover, we naturally infer, that, like us, it moves itself. Another example is borrow'd from Maupertuis. “ As there is no “ known space of the earth covered with 6C water so large as the Terra Australis in
cognita, we may reasonably infer, that
“ fo great a part of the earth is not alto
gether sea, but that there must be some
proportion of land.” The uniformity of nature with respect to the intermixture of sea and land, is an argument that affords but a very slender degree of conviction; and from late voyages it is discovered, that the argument holds not in fact. The following argument of the same kind, tho' it cannot be much rely'd on, seems however better founded. “ The inhabit
ants of the northern hemisphere, have,
in arts and sciences, excelled such of the “ fouthern as we have any knowledge of: · “ and therefore among the latter we ought
not to expect many arts, nor much cul66 tivation.'
After a fatiguing investigation of numberless particulars which divide and scatter the thought, it may not be unpleasant to bring all under one view by a succinct recapitulation.
We have two means for discovering truth and acquiring knowledge, viz. intuition and reasoning. By intuition we discover subjects and their attributes, palfions, internal action, and in short every thing that is matter of fact. By intuition
we also discover several relations. There are some facts and many relations, thaç cannot be discovered by a single act of intuition, but require several such acts linked together in a chain of reafoning.
Knowledge acquired by intuition, includes for the most part certainty: in some instances it includes probability only. Knowledge acquired by reasoning, frequently includes certainty; but more frequently includes probability only.
Probable knowledge, whether founded on intuition or on reasoning, is termed opinion when it concerns relations; and is termed belief when it concerns facts. Where knowledge includes certainty, it retains its proper name.
Reasoning that produces certainty, is termed demonstrative; and is termed probable, when it only produces probability.
Demonstrative reasoning is of two kinds. The first is, where the conclusion is derived from the nature and inherent properties of the subject : mathematical reasoning is of that kind; and perhaps the only instance. The second is, where the conclusion is derived from some proposition, of which we are certain by intuition.
Probable reasoning is endless in its van rieties; and affords different degrees of conviction, depending on the nature of the subject upon which it is employ’d.
A Progress from infancy to maturity in
the mind of man, similar to that in his body, has been often mentioned. The external senses, being early necessary for self-preservation, arrive quickly at maturity. The internal sentes are of a flower growth, as well as every other mental power : their maturity would be of little or no 'use while the body is weak, and unfit for action. Reasoning, as observed in the first section, requires two mental
power of invention, and that of perceiving relations. By the former are discovered intermediate propositions, having the same relation to the fundamental proposition and to the conclusion;
and that relation is verified by the latter. Both powers are necessary to the person who frames an argument, or a chain of reasoning: the latter only, to the person who judges of it. Savages are miserably deficient in both. With respect to the former, a savage may have from his nature a talent for invention; but it will stand him in little stead without a stock of ideas enabling him to select what may answer his purpose; and a favage has no opportunity to acquire such a stock. With respect to the latter, he knows little of relations. And how should he know, when both study and practice are necessary for distinguishing between relations ? The understanding, at the same time, is among the illiterate obsequious to passion and prepoffeffion; and among them the imagination acts without control, forming conclusions often no better than mere dreams. In short, considering the many causes that mislead from just reasoning, in days especially of ignorance, the erroneous and absurd opinions that have prevailed in the world, and that continue in some measure to prevail, are far from being surprising. Were reason our only