| The difference, therefore, of our conduct in preferring the greater number depends not upon our passions, but upon custom, and general rules. |
| We have found in a multitude of instances, that the augmenting the numbers of any sum augments the passion, where the numbers are precise and the difference sensible. |
| The mind can perceive from its immediate feeling, that three guineas produce a greater passion than two; and this it transfers to larger numbers, because of the resemblance; and by a general rule assigns to a thousand guineas, a stronger passion than to nine hundred and ninety nine. |
| These general rules we shall explain presently. |
| But beside these two species of probability, which a-re derived from an imperfect experience and from contrary causes, there is a third arising from ANALOGY, which differs from them in some material circumstances. |
| According to the hypothesis above explained all kinds of reasoning from causes or effects are founded on two particulars, viz., the constant conjunction of any two objects in all past experience, and the resemblance of a present object to any one of them. |
| The effect of these two particulars is, that the present object invigorates and inlivens the imagination; and the resemblance, along with the constant union, conveys this force and vivacity to the related idea; which we are therefore said to believe, or assent to. |
| If you weaken either the union or resemblance, you weaken the principle of transition, and of consequence that belief, which arises from it. |
| The vivacity of the first impression cannot be fully conveyed to the related idea, either where the conjunction of their objects is not constant, or where the present impression does not perfectly resemble any of those, whose union we are accustomed to observe. |
| In those probabilities of chance and causes above-explained, it is the constancy of the union, which is diminished; and in the probability derived from analogy, it is the resemblance only, which is affected. |
| Without some degree of resemblance, as well as union, it is impossible there can be any reasoning: but as this resemblance admits of many different degrees, the reasoning becomes proportionably more or less firm and certain. |
| An experiment loses of its force, when transferred to instances, which are not exactly resembling; though it is evident it may still retain as much as may be the foundation of probability, as long as there is any resemblance remaining. |
| SECT. XIII. OF UNPHILOSOPHICAL PROBABILITY. |
| All these kinds of probability are received by philosophers, and allowed to be reasonable foundations of belief and opinion. |
| But there are others, that are derived from the same principles, though they have not had the good fortune to obtain the same sanction. |
| The first probability of this kind may be accounted for thus. |
| The diminution of the union, and of the resemblance, as above explained, diminishes the facility of the transition, and by that means weakens the evidence; and we may farther observe, that the same diminution of the evidence will follow from a diminution of the impression, and from the shading of those colours, under which it appears to the memory or senses. |
| The argument, which we found on any matter of fact we remember, is more or less convincing according as the fact is recent or remote; and though the difference in these degrees of evidence be not received by philosophy as solid and legitimate; because in that case an argument must have a different force to day, from what it shall have a month hence; yet notwithstanding the opposition of philosophy, it is certain, this circumstance has a considerable influence on the understanding, and secretly changes the authority of the same argument, according to the different times, in which it is proposed to us. |
| A greater force and vivacity in the impression naturally conveys a greater to the related idea; and it is on the degrees of force and vivacity, that the belief depends, according to the foregoing system. |
| There is a second difference, which we may frequently observe in our degrees of belief and assurance, and which never fails to take place, though disclaimed by philosophers. |
| An experiment, that is recent and fresh in the memory, affects us more than one that is in some measure obliterated; and has a superior influence on the judgment, as well as on the passions. |