Philosophical Works, v. 1 (of 4): Including All the Essays, and Exhibiting the More Important Alterations and Corrections in the Successive Editions Published by the Author
David Hume · en
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, 'tis 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.