ld proceed
upon that principle, that instances, of which we have had no experience,
must resemble those, of which we have had experience, and that the
course of nature continues always uniformly the same. In order therefore
to clear up this matter, let us consider all the arguments, upon which
such a proposition may be supposed to be founded; and as these must be
derived either from knowledge or probability, let us cast our eye on
each of these degrees of evidence, and see whether they afford any just
conclusion of this nature.

Our foregoing method of reasoning will easily convince us, that there
can be no demonstrative arguments to prove, that those instances, of
which we have, had no experience, resemble those, of which we have had
experience. We can at least conceive a change in the course of nature;
which sufficiently proves, that such a change is not absolutely
impossible. To form a clear idea of any thing, is an undeniable
argument for its possibility, and is alone a refutation of any pretended
demonstration against it.

Probability, as it discovers not the relations of ideas, considered as
such, but only those of objects, must in some respects be founded on the
impressions of our memory and senses, and in some respects on our ideas.
Were there no mixture of any impression in our probable reasonings, the
conclusion would be entirely chimerical: And were there no mixture
of ideas, the action of the mind, in observing the relation, would,
properly speaking, be sensation, not reasoning. It is therefore
necessary, that in all probable reasonings there be something present
to the mind, either seen or remembered; and that from this we infer
something connected with it, which is not seen nor remembered.

The only connexion or relation of objects, which can lead us beyond the
immediate impressions of our memory and senses, is that of cause and
effect; and that because it is the only one, on which we can found a
just inference from one object to another. The idea of cause and effect
is derived from experience, which informs us, that such particular
objects, in all past instances, have been constantly conjoined with
each other: And as an object similar to one of these is supposed to
be immediately present in its impression, we thence presume on the
existence of one similar to its usual attendant. According to this
account of things, which is, I think, in every point unquestionable,
probability is founded on the presumpt