Entia non sunt multiplicanda praeter necessitatem.
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Entities should not be multiplied beyond necessity.
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Though widely cited as Occam's razor, the popular wording is not found in his extant works.William of Occam
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There never was a sounder logical maxim of scientific procedure than Ockham's razor: Entia non sunt multiplicanda praeter necessitatem. That is to say; before you try a complicated hypothesis, you should make quite sure that no simplification of it will explain the facts equally well. No matter if it takes fifty generations of arduous experimentation to explode the simpler hypothesis, and no matter how incredible it may seem that that simpler hypothesis should suffice, still fifty generations are nothing in the life of science, which has all time before it; and in the long run, say in some thousands of generations, time will be economized by proceeding in an orderly manner, and by making it an invariable rule to try the simpler hypothesis first. Indeed, one can never be sure that the simpler hypothesis is not the true one, after all, until its cause has been fought out to the bitter end. But you will mark the limitation of my approval of Ockham's razor. It is a sound maxim of scientific procedure. If the question be what one ought to believe, the logic of the situation must take other factors into account. Speaking strictly, belief is out of place in pure theoretical science, which has nothing nearer to it than the establishment of doctrines, and only the provisional establishment of them, at that. Compared with living belief it is nothing but a ghost. If the captain of a vessel on a lee shore in a terrific storm finds himself in a critical position in which he must instantly either put his wheel to port acting on one hypothesis, or put his wheel to starboard acting on the contrary hypothesis, and his vessel will infallibly be dashed to pieces if he decides the question wrongly, Ockham's razor is not worth the stout belief of any common seaman. For stout belief may happen to save the ship, while Entia non sunt multiplicanda praeter necessitatem would be only a stupid way of spelling Shipwreck. Now in matters of real practical concern we are all in something like the situation of that sea-captain.
Charles Sanders Peirce
Omnia periclitabuntur aliter accipi quam sunt, et amittere quod sunt dum aliter accipiuntur, si aliter quam sunt cognominantur. Fides nominum salus est proprietatum.
Tertullian
Sunt item, quae appellantur alces. Harum est consimilis capris figura et varietas pellium, sed magnitudine paulo antecedunt mutilaeque sunt cornibus et crura sine nodis articulisque habent neque quietis causa procumbunt neque, si quo adflictae casu conciderunt, erigere sese aut sublevare possunt. His sunt arbores pro cubilibus: ad eas se applicant atque ita paulum modo reclinatae quietem capiunt. Quarum ex vestigiis cum est animadversum a venatoribus, quo se recipere consuerint, omnes eo loco aut ab radicibus subruunt aut accidunt arbores, tantum ut summa species earum stantium relinquatur. Huc cum se consuetudine reclinaverunt, infirmas arbores pondere adfligunt atque una ipsae concidunt.
Julius Caesar
Non semper ea sunt quae videntur.
Phaedrus
Horum omnium fortissimi sunt Belgae.
Julius Caesar
William of Occam
William, Prince of Wales
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