possesses some weight, and bestows on the conclusion a certain degree of probability; of all which, accumulated, the credibility of the fact is compounded. Thus, the proof, that the Romans once possessed Great Britain, is made up of a variety of independent arguments: as, immemorial tradition; the testimony of historians; the ruins of Roman buildings, camps, and walls; Roman coins, inscriptions, and the like. These are independent arguments; but they all conspire to establish the fact. 92. Sixthly. It may be further noticed, that the obstacles, which occur in the practice of these two modes of reasoning, are of different kinds. Those, which impede our progress in demonstration, arise from the large number of intermediate steps, and the difficulty of finding suitable media of proof. In moral reasoning, the processes are usually short, and the chief obstacles, by which we are retarded, arise from the want of exact definitions to our words; the difficulty of keeping steadily in view the various circumstances, on which our judgment should be formed; and from the prejudices arising from early impressions and associations. 93. It should be remarked here. that the epithet probable, as applied by logicians to the evidence of moral reasoning, has a technical meaning, altogether different from its usual signification. In common discourse, it is applied to evidence, which does not command a full assent; but in logical discussions, it has a more comprehensive meaning, not only including every subordinate degree of moral evidence, but also the highest. In this latter sense, it is not to be considered as implying any deficiency of proof, but as contradistinguishing one species of proof from another;-not as opposed to what is certain, but to what may be demonstrated after the manner of mathematicians;-not as denoting the degree of evidence, but its nature. It is the more important to keep in mind this distinction between the popular and technical meaning of the term probable, as the neglect or misapprehension of it has given origin to a distrust of moral reasoning, as inferior in evidence to mathematical demonstration; and induced many authors to seek for a mode of proof altogether unattainable in moral inquiries; and which, if it could be attained, would not be less liable to the cavils of scepticks.* CHAPTER THIRD. INDUCTION. 94. The first kind of moral reasoning is that, by which we infer general truths from particular facts, that have fallen under our observation. This has been called the method of induction. It is founded on the belief, that the course of nature is governed by uniform laws, and that things will happen in future, as we have observed them to happen in time past. We can have no proof of a permanent connexion between any events, or between any two qualities either of body or mind. The only reason for supposing such a connexion in any instance is, that we have invariably found certain things to have been conjoined in fact; and this experience, in many cases, produces a conviction equal to that of demonstration. 95. When a property has been found in Campbell, Phil * Reid, Intellectual Powers, essay vii. ch. 3. Rhet. b. i. ch. 5. sect. 2. Gambier, Mor. Evid. ch. 1. Stewart, Elem, Phil. of Mind, vol. i. Introd. part ii. sect. 2. vol. ii. ch. 2. sect. 4. many subjects of a similar kind, and no contradictory instance has been discovered, though diligently sought, we have an irresistible persuasion, that the same property belongs to all the individuals of that class. Thus, having applied a magnet to several masses of iron, and found uniformly a strong attraction to take place, we feel no doubt, that it belongs to the nature of iron to be thus affected by that substance; and, though our experience reaches only to a small part of the masses of iron in existence, we assert with confidence, that all iron is susceptible of magnetical attraction. So, having often noticed, that, by the application of heat to a certain degree, water is made to boil, and that, in the absence of heat to a certain degree, it becomes congealed; and having ascertained these changes to be uniform, so far as they have been observed by ourselves and others, we readily ascribe them to the nature of water, and conclude, that in every country water will boil or freeze, on being exposed to those opposite degrees of temperature. 96. In this way, by observations and experiments on individuals of a similar kind, noticing with exactness their agreement, or the circum stances, in which they differ, we obtain general truths relating to the properties and laws of material objects. By the same inductive process we investigate the laws, which govern the phenomena of mind. Thus, from experience, it has been ascertained, that, when two ideas have been often presented to the mind in immediate succession, they acquire a tendency mutually to suggest each other; so that, when either of them occurs to our thoughts, the other readily follows it. We learn also from experience, that the durability of past impressions on the mind depends greatly on the attention, with which they were at first received. From the uniformity of these facts we are taught, that contiguity in time or place is a principle of association; and that attention is necessary to memory. 97. As we deduce the common properties of a single class of beings from observations on individuals of that class, so, by comparing individuals of different classes, we discover important resemblances between one species and another, and are enabled to obtain more extensive conclusions. Thus, having seen the milk of several animals of different species, and |