ABSTRACT
David Hume explains a number of important mental phenomena as the effects of what he calls the principles of the association of ideas. Ideas are attracted to each other in a systematic way. The principles of mental attraction are supposed to order the mental world in much the same way as Newton's law of gravitational attraction governs the behaviour of particles in the physical world. Liveliness and force are the criteria according to which Hume classifies all the perceptions of the mind. The 'additional force and vivacity' of a belief comes from the more forceful and vivacious impression of sensation to which it is related. Vivacity is transferred from an impression to the idea of its associate in a degree sufficient to make that idea a belief Hume makes belief 'more properly an act of the sensitive, than of the cognitive part of our natures', a matter not of reason, but of 'feeling, or sentiment'.
