But, secondly, it is equally obvious in this species of reasoning, that
if the transference of the past to the future were founded merely on a
conclusion of the understanding, it could never occasion any belief or
assurance. When we transfer contrary experiments to the future, we
can only repeat these contrary experiments with their particular
proportions; which could not produce assurance in any single event, upon
which we reason, unless the fancy melted together all those images
that concur, and extracted from them one single idea or image, which is
intense and lively in proportion to the number of experiments from which
it is derived, and their superiority above their antagonists. Our past
experience presents no determinate object; and as our belief, however
faint, fixes itself on a determinate object, it is evident that the
belief arises not merely from the transference of past to future, but
from some operation of the fancy conjoined with it. This may lead us
to conceive the manner, in which that faculty enters into all our
reasonings.
I shall conclude this subject with two reflections, which may deserve
our attention. The FIRST may be explained after this manner. When the
mind forms a reasoning concerning any matter of fact, which is
only probable, it casts its eye backward upon past experience, and
transferring it to the future, is presented with so many contrary
views of its object, of which those that are of the same kind uniting
together, and running into one act of the mind, serve to fortify and
inliven it. But suppose that this multitude of views or glimpses of an
object proceeds not from experience, but from a voluntary act of the
imagination; this effect does not follow, or at least, follows not in
the same degree. For though custom and education produce belief by such
a repetition, as is not derived from experience, yet this requires
a long tract of time, along with a very frequent and undesigned
repetition. In general we may pronounce, that a person who would
voluntarily repeat any idea in his mind, though supported by one past
experience, would be no more inclined to believe the existence of its
object, than if he had contented himself with one survey of it.
Beside the effect of design; each act of the mind, being separate and
independent, has a separate influence, and joins not its force with that
of its fellows. Not being united by any common object, producing them,
they have no relation to each other; and consequently make no transition
or union of forces. This phænomenon we shall understand better
afterwards.