12 ideas
9108 | From an impossibility anything follows [William of Ockham] |
Full Idea: From an impossibility anything follows ('quod ex impossibili sequitur quodlibet'). | |
From: William of Ockham (Summa totius logicae [1323], III.c.xxxvi) | |
A reaction: The hallmark of a true logician, I suspect, is that this opinion is really meaningful and important to them. They yearn to follow the logic wherever it leads. Common sense would seem to say that absolutely nothing follows from an impossibility. |
9107 | A proposition is true if its subject and predicate stand for the same thing [William of Ockham] |
Full Idea: If in the proposition 'This is an angel' subject and predicate stand for the same thing, the proposition is true. | |
From: William of Ockham (Summa totius logicae [1323], II.c.ii) | |
A reaction: An interesting statement of what looks like a correspondence theory, employing the idea that both the subject and the predicate have a reference. I think Frege would say that 'x is an angel' is unsaturated, and so lacks reference. |
16300 | Ockham had an early axiomatic account of truth [William of Ockham, by Halbach] |
Full Idea: Theories structurally very similar to axiomatic compositional theories of truth can be found in Ockham's 'Summa Logicae'. | |
From: report of William of Ockham (Summa totius logicae [1323]) by Volker Halbach - Axiomatic Theories of Truth 3 |
8942 | Lukasiewicz's L3 logic has three truth-values, T, F and I (for 'indeterminate') [Lukasiewicz, by Fisher] |
Full Idea: In response to Aristotle's sea-battle problem, Lukasiewicz proposed a three-valued logic that has come to be known as L3. In addition to the values true and false (T and F), there is a third truth-value, I, meaning 'indeterminate' or 'possible'. | |
From: report of Jan Lukasiewicz (Elements of Mathematical Logic [1928], 7.I) by Jennifer Fisher - On the Philosophy of Logic | |
A reaction: [He originated the idea in 1917] In what sense is the third value a 'truth' value? Is 'I don't care' a truth-value? Or 'none of the above'? His idea means that formalization doesn't collapse when things get obscure. You park a few propositions under I. |
9106 | The word 'every' only signifies when added to a term such as 'man', referring to all men [William of Ockham] |
Full Idea: The syncategorematic word 'every' does not signify any fixed thing, but when added to 'man' it makes the term 'man' stand for all men actually. | |
From: William of Ockham (Summa totius logicae [1323], I.c.iv) | |
A reaction: Although quantifiers may have become a part of formal logic with Frege, their importance is seen from Aristotle onwards, and it is clearly a key part of William's understanding of logic. |
9113 | Just as unity is not a property of a single thing, so numbers are not properties of many things [William of Ockham] |
Full Idea: Number is nothing but the actual numbered things themselves. Hence just as unity is not an accident added to the thing which is one, so number is not an accident of the things which are numbered. | |
From: William of Ockham (Summa totius logicae [1323], I.c.xliv) | |
A reaction: [William does not necessarily agree with this view] It strikes me as a key point here that any account of the numbers had better work for 'one', though 'zero' might be treated differently. Some people seem to think unity is a property of things. |
9110 | The words 'thing' and 'to be' assert the same idea, as a noun and as a verb [William of Ockham] |
Full Idea: The words 'thing' and 'to be' (esse) signify one and the same thing, but the one in the manner of a noun and the other in the manner of a verb. | |
From: William of Ockham (Summa totius logicae [1323], III,II,c,xxvii) | |
A reaction: Well said - as you would expect from a thoroughgoing nominalist. I would have thought that this was the last word on the subject of Being, thus rendering any need for me to read Heidegger quite superfluous. Or am I missing something? |
15388 | Universals are single things, and only universal in what they signify [William of Ockham] |
Full Idea: Every universal is one particular thing and it is not a universal except in its signification, in its signifying many thing. | |
From: William of Ockham (Summa totius logicae [1323]), quoted by Claude Panaccio - Medieval Problem of Universals 'William' | |
A reaction: Sounds as if William might have liked tropes. It seems to leave the problem unanswered (the 'ostrich' problem?). How are they able to signify in this universal way, if each thing is just distinct and particular? |
9109 | If essence and existence were two things, one could exist without the other, which is impossible [William of Ockham] |
Full Idea: If essence and existence were two things, then no contradiction would be involved if God preserved the essence of a thing in the world without its existence, or vice versa, its existence without its essence; both of which are impossible. | |
From: William of Ockham (Summa totius logicae [1323], III,II,c,xxvii) | |
A reaction: Not that William is using the concept of a supreme mind as a tool in argument. His denial of essence as something separable is presumably his denial of the Aristotelian view of universals, as well as of the Platonic view. |
9105 | Some concepts for propositions exist only in the mind, and in no language [William of Ockham] |
Full Idea: Conceptual terms and the propositions formed by them are those mental words which do not belong to any language; they remain only in the mind and cannot be uttered exteriorly, though signs subordinated to these can be exteriorly uttered. | |
From: William of Ockham (Summa totius logicae [1323], I.c.i) | |
A reaction: [He cites Augustine] A glimmer of the idea of Mentalese, and is probably an integral part of any commitment to propositions. Quine would hate it, but I like it. Logicians seem to dislike anything that cannot be articulated, but brains are like that. |
541 | Virtue comes more from habit than character [Critias] |
Full Idea: More men are good through habit than through character. | |
From: Critias (fragments/reports [c.440 BCE], B09), quoted by John Stobaeus - Anthology 3.29.41 |
542 | Fear of the gods was invented to discourage secret sin [Critias] |
Full Idea: When the laws forbade men to commit open crimes of violence, and they began to do them in secret, a wise and clever man invented fear of the gods for mortals, to frighten the wicked, even if they sin in secret. | |
From: Critias (fragments/reports [c.440 BCE], B25), quoted by Sextus Empiricus - Against the Professors (six books) 9.54 |