Thomas Hobbes

“ But if running through many conclusions, we come to none that are absurd, then we think the supposition probable; likewise we think probable whatsoever proposition we admit for truth by error of reasoning, or from trusting to other men. ”

“ There are two things necessarily implied in this word knowledge; the one is truth, the other evidence; for what is not true, can never be known. For let a man say he knoweth a thing never so well, if the same shall afterwards appear to be false, he is driven to a confession, that it was not knowledge, but opinion. Likewise, if the truth be not evident, though a man holdeth it, yet is his knowledge of it no more than theirs that hold the contrary. For if truth were enough to make it knowledge, all truths were known: which is not so. ”

“ Belief, which is the admitting of propositions upon trust, in many cases is no less free from doubt, than perfect and manifest knowledge. For as there is nothing whereof there is not some cause; so, when there is doubt, there must be some cause thereof conceived. ”

“ It is either science or opinion which we commonly mean by the word conscience: for men say that such and such a thing is true upon, or in their consciences; which they never do, when they think it doubtful ”

“ Now there be many things which we receive from report of others, of which it is impossible to imagine any cause of doubt: for what can be opposed against the consent of all men, in things they can know, and have no cause to report otherwise than they are (such as is a great part of our histories) , unless a man would say that all the world had conspired to deceive him. ”

“ And thus much of sense, imagination, discursion, ratiocination, and knowledge, which are the acts of our power cognitive, or conceptive. That power of the mind which we call motive, differeth from the power motive of the body. for the power motive of the body is that by which it moveth other bodies, which we call strength: but the power motive of the mind, is that by which the mind giveth animal motion to that body wherein it existeth ”