nd
effects, and that which depends upon an interrupted and uncertain. It is
indeed evident, that in all determinations, where the mind decides from
contrary experiments, it is first divided within itself, and has an
inclination to either side in proportion to the number of experiments
we have seen and remember. This contest is at last determined to the
advantage of that side, where we observe a superior number of these
experiments; but still with a diminution of force in the evidence
correspondent to the number of the opposite experiments. Each
possibility, of which the probability is composed, operates separately
upon the imagination; and it is the larger collection of possibilities,
which at last prevails, and that with a force proportionable to its
superiority. All these phenomena lead directly to the precedent system;
nor will it ever be possible upon any other principles to give a
satisfactory and consistent explication of them. Without considering
these judgments as the effects of custom on the imagination, we shall
lose ourselves in perpetual contradiction and absurdity.

SECT. XIV. OF THE IDEA OF NECESSARY CONNEXION.

Having thus explained the manner, in which we reason beyond our
immediate impressions, and conclude that such particular causes must
have such particular effects; we must now return upon our footsteps to
examine that question, which [Sect. 2.] first occured to us, and which
we dropt in our way, viz. What is our idea of necessity, when we say
that two objects are necessarily connected together. Upon this head I
repeat what I have often had occasion to observe, that as we have
no idea, that is not derived from an impression, we must find some
impression, that gives rise to this idea of necessity, if we assert we
have really such an idea. In order to this I consider, in what objects
necessity is commonly supposed to lie; and finding that it is always
ascribed to causes and effects, I turn my eye to two objects supposed to
be placed in that relation; and examine them in all the situations,
of which they are susceptible. I immediately perceive, that they are
contiguous in time and place, and that the object we call cause precedes
the other we call effect. In no one instance can I go any farther,
nor is it possible for me to discover any third relation betwixt these
objects. I therefore enlarge my view to comprehend several instances;
where I find like objects always existing in like relations o