What Has Probability to do with Strength of Belief

There is an old dispute in Western philosophy about whether the human mind is active or passive in the process of acquiring knowledge concerning the facts and laws of Nature. According to Descartes we articulate such knowledge in voluntary judgements whereby we either assent to or dissent from some relevant mental representation. Thus each item of conscious knowledge is gained by an act of free-will. But according to Hume we learn about Nature via the formation of beliefs and-on his view-a person’s beliefs are not controllable by his will. In other words on Hume’s view our knowledge of nature is not acquired by voluntary acts of cognitive judgement, as Descartes held, but by the involuntary growth of cognitive feelings.