"be no second truths, nor third, nor indeed any "truth at all."

So much for intuitive evidence, in the extensive meaning which hath here been given to that term, as including every thing whose evidence results from the simple contemplation of the ideas or perceptions which form the proposition under conside ration, and requires not the intervention of any third idea as a medium of proof. This, for order's sake, I have distributed into three classes, the truths of pure intellection, of consciousness, and of com. The first may be denominated metaphysical, the second physical, the third moral; all of them natural, original, and unaccountable.

mon sense.

SECTION II.

Of deductive evidence.

PART I.-Division of the subject into scientific and moral, with the principal distinctions between them.

ALL rational or deductive evidence is derived from one or other of these two sources: from the invariable properties or relations of general ideas; or from the actual, though perhaps, variable connexions, subsisting among things. The former we call demonstrative, the latter moral. Demonstration is built on pure intellection, and consisteth in

an uninterrupted series of axioms. That propositions formerly demonstrated are taken into the series, doth not in the least invalidate this account; inasmuch as these propositions are all resolvable into axioms, and are admitted as links in the chain; not because necessary, but merely to avoid the useless prolixity which frequent and tedious repetitions of proofs formerly given would occasion. Moral evidence is founded on the principles we have from consciousness and common sense, improved by experience; and as it proceeds on this general presumption or moral axiom, that the course of nature in time to come, will be similar to what it hath been hitherto, it decides, in regard to particulars, concerning the future from the past, and concerning things unknown, from things familiar to us. The first is solely conversant about number and extension, and about those other qualities which are measurable by these. Such are duration, velocity, and weight. With regard to such qualities as pleasure and pain, virtue and vice, wisdom and folly, beauty and deformity, though they admit degrees, yet, as there is no standard or common measure, by which their differences and proportions can be ascertained and expressed in numbers, they can never become the subject of demonstrative reasoning. Here rhetoric, it must be acknowledged, hath little to do. Simplicity of diction, and precision in arrangement, whence results perspicuity, are, as was

observed already, all the requisites. The proper province of rhetoric is the second, or moral evidence; for to the second belong all decisions concerning fact, and things without us.

But that the nature of moral evidence may be better understood, it will not be amiss to remark a few of the most eminent differences between this and the demonstrative.

The first difference that occurs is in their subjects. The subject of the one is, as hath been observed, abstract independent truth, or the unchangeable and necessary relations of ideas; that of the other, the real, but often changeable and contingent connexions that subsist among things actually existing. Abstract truths, as the properties of quanti ty, have no respect to time or to place, no dependence on the volition of any being, or on any cause whatever, but are eternally and immutably the

same.

The very reverse of all this generally obtains with regard to fact. In consequence of what has been now advanced, assertions opposite to truths of the former kind, are not only false, but absurd. They are not only not true, but it is impossible they should be true, whilst the meanings of the words (and consequently the ideas compared) remain the same. This doth not hold commonly in any other kind of evidence. Take, for instance, of

the first kind, the following affirmations, The cube of two is the half of sixteen.'- The square of the hypotenuse is equal to the sum of the squares of the sides. If equal things be taken ⚫ from equal things, the remainders will be equal.' Contrary propositions, as, The cube of two is · more than the half of sixteen.'-' The square of • the hypotenuse is less than the sum of the squares • of the sides. If equal things be taken from

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equal things, the remainders will be unequal," are chargeable, not only with falsity, but with absurdity, being inconceivable and contradictory. Whereas, to these truths which we acquire by moral evidence, Cæsar overcame Pompey.'- The sun will rise to-morrow.'- All men will die,' the opposite assertions, though untrue, are easily conceivable without changing, in the least, the im port of the words, and therefore do not imply a contradiction.

The second difference I shall remark is, that mo ral evidence admits degrees, demonstration doth not. This is a plain consequence of the preceding diffe rence. Essential or necessary truth, the sole object of the latter, is incompatible with degree. And though actual truth, or matter of fact, be the ultimate aim of the former, likelihood alone, which is susceptible of degree, is usually the utmost attainment. Whatever is exhibited as demonstration, is either mere illusion, and so no evidence at all, or

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absolutely perfect. There is no medium. In moral reasoning we ascend from possibility, by an insensible gradation, to probability, and thence, in the same manner, to the summit of moral certainty. On this summit, or on any of the steps leading to it, the conclusion of the argument may rest. Hence the result of that is, by way of eminence, denominated science; and the evidence itself is termed scientific ; the result of this is frequently (not always) intitled to no higher denomination than opinion. Now, in the mathematical sciences, no mention is ever made of opinions.

The third difference is, that in the one there never can be any contrariety of proofs; in the other, there not only may be, but almost always is. If one demonstration were ever capable of being refuted, it could be solely by another demonstration, this being the only sort of evidence adapted to the subject, and the only sort by which the former could be matched. But, to suppose that contraries are demonstrable, is to suppose that the same proposition is both true and false, which is a manifest contradiction. Consequently, if there should ever be the appearance of demonstration on opposite sides, that on one side must be fallacious and sophis tical. It is not so with moral evidence, for unless in a few singular instances, there is always real, not apparent evidence on both sides. There are contrary experiences, contrary presumptions, contrary