David Hume

“ Necessity is regular and certain. Human conduct is irregular and uncertain. The one, therefore, proceeds not from the other.
To this I reply, that in judging of the actions of men we must proceed upon the same maxims, as when we reason concerning external objects. When any phænomena are constantly and invariably conjoin'd together, they acquire such a connexion in the imagination, that it passes from one to the other, without any doubt or hesitation. ”

“ Are the changes of our body from infancy to old age more regular and certain than those of our mind and conduct? And wou'd a man be more ridiculous, who wou'd expect that an infant of four years old will raise a weight of three hundred pound, than one, who from a person of the same age, wou'd look for a philosophical reasoning, or a prudent and well-concerted action? ”

“ There is no philosopher, whose judgment is so riveted to this fantastical system of liberty, as not to acknowledge the force of moral evidence, and both in speculation and practice proceed upon it, as upon a reasonable foundation. Now moral evidence is nothing but a conclusion concerning the actions of men, deriv'd from the consideration of their motives, temper and situation. ”

“ There is a general course of nature in human actions, as well as in the operations of the sun and the climate. There are also characters peculiar to different nations and particular persons, as well as common to mankind. The knowledge of these characters is founded on the observation of an uniformity in the actions, that flow from them; and this uniformity forms the very essence of necessity. ”

“ And indeed, when we consider how aptly natural and moral evidence cement together, and form only one chain of argument betwixt them, we shall make no scruple to allow, that they are of the same nature, and deriv'd from the same principles. A prisoner, who has neither money nor interest, discovers the impossibility of his escape, as well from the obstinacy of the goaler, as from the walls and bars with which he is surrounded ”

“ And what creature departs more widely, not only from right reason, but from his own character and disposition? An hour, a moment is sufficient to make him change from one extreme to another, and overturn what cost the greatest pain and labour to establish. ”

“ It has been observ'd already, that in no single instance the ultimate connexion of any objects is discoverable, either by our senses or reason, and that we can never penetrate so far into the essence and construction of bodies, as to perceive the principle, on which their mutual influence depends. 'Tis their constant union alone, with which we are acquainted; and 'tis from the constant union the necessity arises. If objects had not an uniform and regular conjunction with each other, we shou'd never arrive at any idea of cause and effect ”

“ And for a like reason we must allow, that human society is founded on like principles; and our reason in the latter use, is better than even that in the former; because we not only observe, that men always seek society, but can also explain the principles, on which this universal propensity is founded. ”

“ But below this there are many inferior degrees of evidence and probability, nor does one single contrariety of experiment entirely destroy all our reasoning. The mind balances the contrary experiments, and deducting the inferior from the superior, proceeds with that degree of assurance or evidence, which remains. Even when these contrary experiments are entirely equal, we remove not the notion of causes and necessity ”

“ Every object is determin'd by an absolute fate to a certain degree and direction of its motion, and can no more depart from that precise line, in which it moves, than it can convert itself into an angel, or spirit, or any superior substance. ”

“ The skin, pores, muscles, and nerves of a day-labourer are different from those of a man of quality: So are his sentiments, actions and manners. The different stations of life influence the whole fabric, external and internal ”

“ The same kind of reasoning runs thro' politics, war, commerce, oeconomy, and indeed mixes itself so entirely in human life, that 'tis impossible to act or subsist a moment without having recourse to it. ”