PROBABILITY is nothing but the ap pea•ance of the agreement or disagree ment of two ideas, by the intervention of proofs whose connection is not constant and immutable, or is not perceived to be so ; but is, or appears for the most part to be so ; and is enough- to induce the mind to judge the proposition true or false, rather than the contrary.
Of probability there are degrees, from the neighbourhood of certainty and de monstration, quite down to improbability and unlikeness, even to the confines of impossibility ; and also degrees of assent, from certain knowledge, and, what is next to it, full assurance and confidence, quite down to conjecture, doubt, dist rost, and disbelief. That proposition then is probable, for which there are arguments, or proof, to make it pass or be received for true. Probability being then to sup ply the defect of our knowledge, is al w.,ys conversant about a thing whereof we have no certainty, but only sonic in ducements to receive it for true. The
grounds of it are, in short, these two fol lowing i First, the conformity of any thing with our own knowledge, experi ence, or observation. Secondly, the testi mony of others vouching their observa tion and experience. In the testimony of others, is to be considered, 1. the number; 2 the integrity ; 3. the skill of the witnesses ; 4. the design of the au thor, if it be a testimony cited out of a book ; 5. the consistency of the parts and circumstances of the relation ; 6. contra ry testimonies. The mind, before it ra tionally assents or dissents to any proba ble proposition, ought to examine all the grounds of probability, and see how they make, more or less, for or against it; and, upon a due balancing the whole, reject or receive it, with a more or less firm as sent, according to the preponderance of the greater grounds of probability on one side or the other. •