Let us now join these three observations, and see what conclusion we can
draw from them. To every probability there is an opposite possibility.
This possibility is composed of parts, that are entirely of the same
nature with those of the probability; and consequently have the same
influence on the mind and understanding. The belief, which attends the
probability, is a compounded effect, and is formed by the concurrence
of the several effects, which proceed from each part of the probability.
Since therefore each part of the probability contributes to the
production of the belief, each part of the possibility must have the
same influence on the opposite side; the nature of these parts being
entirely the same. The contrary belief, attending the possibility,
implies a view of a certain object, as well as the probability does
an opposite view. In this particular both these degrees of belief are
alike. The only manner then, in which the superior number of similar
component parts in the one can exert its influence, and prevail above
the inferior in the other, is by producing a stronger and more lively
view of its object. Each part presents a particular view; and all these
views uniting together produce one general view, which is fuller and
more distinct by the greater number of causes or principles, from which
it is derived.
The component parts of the probability and possibility, being alike
in their nature, must produce like effects; and the likeness of their
effects consists in this, that each of them presents a view of a
particular object. But though these parts be alike in their nature, they
are very different in their quantity and number; and this difference
must appear in the effect as well as the similarity. Now as the view
they present is in both cases full and entire, and comprehends the
object in all its parts, it is impossible that in this particular there
can be any difference; nor is there any thing but a superior vivacity
in the probability, arising from the concurrence of a superior number of
views, which can distinguish these effects.