"he must consult the dictates of self-preservation alone"

"Suppose likewise, that it should be a virtuous man’s fate to fall into the society of ruffians, remote from the protection of laws and government; what conduct must he embrace in that melancholy situation? He sees such a desperate rapaciousness prevail; such a disregard to equity, such contempt of order, such stupid blindness to future consequences, as must immediately have the most tragical conclusion, and must terminate in destruction to the greater number, and in a total dissolution of society to the rest. He, meanwhile, can have no other expedient than to arm himself, to whomever the sword he seizes, or the buckler, may belong: To make provision of all means of defence and security: And his particular regard to justice being no longer of use to his own safety or that of others, he must consult the dictates of self-preservation alone, without concern for those who no longer merit his care and attention."

- David Hume, Enquiries Concerning the Human Understanding and Concerning the Principles of Morals, ed. L. A. Selby-Bigge, M.A. 2nd ed. (Oxford: Clarendon Press, 1902).