2. It is to supply our want of knowledge.
Our knowledge, as has been shown, being very narrow, and we not
happy enough to find certain truth in everything which we have occasion to consider; most of the propositions we
think, reason, discourse--nay, act upon, are such as we cannot have undoubted knowledge of their truth: yet some
of them border so near upon certainty, that we make no doubt at all about them; but assent to them as firmly, and
act, according to that assent, as resolutely as if they were infallibly demonstrated, and that our knowledge of them
was perfect and certain. But there being degrees herein, from the very neighbourhood of certainty and
demonstration, quite down to improbability and unlikeness, even to the confines of impossibility; and also degrees
of assent from full assurance and confidence, quite down to conjecture, doubt, and distrust: I shall come now,
(having, as I think, found out the bounds of human knowledge and certainty,) in the next place, to consider the
several degrees and grounds of probability, and assent or faith.