demonstrative: Of what nature is it, then? To say it is experimental, is
begging the question. For all inferences from experience suppose, as
their foundation, that the future will resemble the past, and that
similar powers will be conjoined with similar sensible qualities. If
there be any suspicion that the course of nature may change, and that
the past may be no rule for the future, all experience becomes useless,
and can give rise to no inference or conclusion. It is impossible,
therefore, that any arguments from experience can prove this resemblance
of the past to the future; since all these arguments are founded on the
supposition of that resemblance. Let the course of things be allowed
hitherto ever so regular; that alone, without some new argument or
inference, proves not that, for the future, it will continue so. In vain
do you pretend to have learned the nature of bodies from your past
experience. Their secret nature, and consequently all their effects and
influence, may change, without any change in their sensible qualities.
This happens sometimes, and with regard to some objects: Why may it not
happen always, and with regard to all objects? What logic, what process
of argument secures you against this supposition? My practice, you say,
refutes my doubts. But you mistake the purport of my question. As an
agent, I am quite satisfied in the point; but as a philosopher, who has
some share of curiosity, I will not say scepticism, I want to learn the
foundation of this inference. No reading, no enquiry has yet been able
to remove my difficulty, or give me satisfaction in a matter of such
importance. Can I do better than propose the difficulty to the public,
even though, perhaps, I have small hopes of obtaining a solution? We
shall at least, by this means, be sensible of our ignorance, if we do
not augment our knowledge.

33. I must confess that a man is guilty of unpardonable arrogance who
concludes, because an argument has escaped his own investigation, that