It is true, when any cause fails of producing its usual effect,
philosophers ascribe not this to any irregularity in nature; but
suppose, that some secret causes, in the particular structure of parts,
have prevented the operation. Our reasonings, however, and conclusions
concerning the event are the same as if this principle had no place.
Being determined by custom to transfer the past to the future, in all
our inferences; where the past has been entirely regular and uniform, we
expect the event with the greatest assurance, and leave no room for any
contrary supposition. But where different effects have been found to
follow from causes, which are to _appearance_ exactly similar, all these
various effects must occur to the mind in transferring the past to the
future, and enter into our consideration, when we determine the
probability of the event. Though we give the preference to that which
has been found most usual, and believe that this effect will exist, we
must not overlook the other effects, but must assign to each of them a
particular weight and authority, in proportion as we have found it to be
more or less frequent. It is more probable, in almost every country of
Europe, that there will be frost sometime in January, than that the
weather will continue open throughout that whole month; though this
probability varies according to the different climates, and approaches
to a certainty in the more northern kingdoms. Here then it seems
evident, that, when we transfer the past to the future, in order to
determine the effect, which will result from any cause, we transfer all
the different events, in the same proportion as they have appeared in
the past, and conceive one to have existed a hundred times, for
instance, another ten times, and another once. As a great number of
views do here concur in one event, they fortify and confirm it to the
imagination, beget that sentiment which we call _belief,_ and give its
object the preference above the contrary event, which is not supported
by an equal number of experiments, and recurs not so frequently to the