Book IV - Chapter XV Of Probability 1.
Probability is the appearance of agreement upon fallible proofs.
It is to supply our want of knowledge. Being that which makes us presume things to be true, before we know them to be so. Probability is likeliness to be true, the very notation of the word signifying such a proposition, for which there be arguments or proofs to make it pass, or be received for true. The entertainment the mind gives this sort of propositions is called belief, assent, or opinion, which is the admitting or receiving any proposition for true, upon arguments or proofs that are found to persuade us to receive it as true, without certain knowledge that it is so. The conformity of anything with our own knowledge, observation, and experience.