An Enquiry Concerning Human Understanding HTML version

VI. Of Probability9
46. Though there be no such thing as Chance in the world; our ignorance of the real cause
of any event has the same influence on the understanding, and begets a like species of
belief or opinion.
There is certainly a probability, which arises from a superiority of chances on any side;
and according as this superiority encreases, and surpasses the opposite chances, the
probability receives a proportionable encrease, and begets still a higher degree of belief
or assent to that side, in which we discover the superiority. If a dye were marked with one
figure or number of spots on four sides, and with another figure or number of spots on the
two remaining sides, it would be more probable, that the former would turn up than the
latter; though, if it had a thousand sides marked in the same manner, and only one side
different, the probability would be much higher, and our belief or expectation of the event
more steady and secure. This process of the thought or reasoning may seem trivial and
obvious; but to those who consider it more narrowly, it may, perhaps, afford matter for
curious speculation.
It seems evident, that, when the mind looks forward to discover the event, which may
result from the throw of such a dye, it considers the turning up of each particular side as
alike probable; and this is the very nature of chance, to render all the particular events,
comprehended in it, entirely equal. But finding a greater number of sides concur in the
one event than in the other, the mind is carried more frequently to that event, and meets it
oftener, in revolving the various possibilities or chances, on which the ultimate result
depends. This concurrence of several views in one particular event begets immediately,
by an inexplicable contrivance of nature, the sentiment of belief, and gives that event the
advantage over its antagonist, which is supported by a smaller number of views, and
recurs less frequently to the mind. If we allow, that belief is nothing but a firmer and
stronger conception of an object than what attends the mere fictions of the imagination,
this operation may, perhaps, in some measure, be accounted for. The concurrence of
these several views or glimpses imprints the idea more strongly on the imagination; gives
it superior force and vigour; renders its influence on the passions and affections more
sensible; and in a word, begets that reliance or security, which constitutes the nature of
belief and opinion.
47. The case is the same with the probability of causes, as with that of chance. There are
some causes, which are entirely uniform and constant in producing a particular effect;
and no instance has ever yet been found of any failure or irregularity in their operation.
Fire has always burned, and water suffocated every human creature: The production of
motion by impulse and gravity is an universal law, which has hitherto admitted of no
exception. But there are other causes, which have been found more irregular and
uncertain; nor has rhubarb always proved a purge, or opium a soporific to every one, who
has taken these medicines. 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