22 ideas
| 23367 | Even pointing a finger should only be done for a reason [Epictetus] |
| Full Idea: Philosophy says it is not right even to stretch out a finger without some reason. | |
| From: Epictetus (fragments/reports [c.57], 15) | |
| A reaction: The key point here is that philosophy concerns action, an idea on which Epictetus is very keen. He rather despise theory. This idea perfectly sums up the concept of the wholly rational life (which no rational person would actually want to live!). |
| 13070 | If definitions must be general, and general terms can't individuate, then Socrates can't be defined [Aquinas, by Cover/O'Leary-Hawthorne] |
| Full Idea: Socrates has no definition if definitions by their nature must be in purely general terms, and if no purely general terms can succeed in uniquely singling out this signated matter. | |
| From: report of Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], 23) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 1.1.2 | |
| A reaction: There seem to be two models. That general terms actually individuate the matter of Socrates, or that they cross-reference to (so to speak) define Socrates 'by elimination', as the only individual that fits. But the latter is a poor definition. |
| 11197 | The definitions expressing identity are used to sort things [Aquinas] |
| Full Idea: What sorts things into their proper genus and species are the definitions that express what they are. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.92) | |
| A reaction: This is straight from Aristotle, though Aristotle's view is a little more complex, I think. If the definitions 'express what they are', then definitions seem to specify the essence. |
| 9358 | There are several logics, none of which will ever derive falsehoods from truth [Lewis,CI] |
| Full Idea: The fact is that there are several logics, markedly different, each self-consistent in its own terms and such that whoever, using it, avoids false premises, will never reach a false conclusion. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.366) | |
| A reaction: As the man who invented modal logic in five different versions, he speaks with some authority. Logicians now debate which version is the best, so how could that be decided? You could avoid false conclusions by never reasoning at all. |
| 9357 | Excluded middle is just our preference for a simplified dichotomy in experience [Lewis,CI] |
| Full Idea: The law of excluded middle formulates our decision that whatever is not designated by a certain term shall be designated by its negative. It declares our purpose to make a complete dichotomy of experience, ..which is only our penchant for simplicity. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.365) | |
| A reaction: I find this view quite appealing. 'Look, it's either F or it isn't!' is a dogmatic attitude which irritates a lot of people, and appears to be dispensible. Intuitionists in mathematics dispense with the principle, and vagueness threatens it. |
| 9364 | Names represent a uniformity in experience, or they name nothing [Lewis,CI] |
| Full Idea: A name must represent some uniformity in experience or it names nothing. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.368) | |
| A reaction: I like this because, in the quintessentially linguistic debate about the exact logical role of names, it reminds us that names arise because of the way reality is; they are not sui generis private games for logicians. |
| 11195 | If affirmative propositions express being, we affirm about what is absent [Aquinas] |
| Full Idea: If being is what makes propositions true, then anything we can express in an affirmative proposition, however unreal, is said to be; so lacks and absences are, since we say that absences are opposed to presences, and blindness exists in an eye. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.92) | |
| A reaction: See Idea 11194 for the alternative Aristotelian approach to being, according to categories. Do absences and lacks have real essences, or causal properties? The absence of the sentry may cause the loss of the city. |
| 11201 | Properties have an incomplete essence, with definitions referring to their subject [Aquinas] |
| Full Idea: Incidental properties have an incomplete essence, and need to refer in their definitions to their subject, lying outside their own genus. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.93) | |
| A reaction: These are 'incidental' properties, but it is a nice question whether properties have essences. Presumably they must have if they are universals, or platonic Forms. The notion of being 'strong' can be defined without specific examples. |
| 11205 | If the form of 'human' contains 'many', Socrates isn't human; if it contains 'one', Socrates is Plato [Aquinas] |
| Full Idea: If (in the Platonic view) manyness was contained in humanness it could never be one as it is in Socrates, and if oneness was part of its definition then Socrates would be Plato and the nature couldn't be realised more than once. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.100) | |
| A reaction: I suppose the reply is that since we are trying to explain one-over-many, then this unusual combination of both manyness and oneness is precisely what distinguishes forms from other ideas. |
| 13090 | The principle of diversity for corporeal substances is their matter [Aquinas, by Cover/O'Leary-Hawthorne] |
| Full Idea: In the view of Aquinas, while substantial form is the ultimate ground of identity and difference of angels, it is matter that provides a principle of diversity in the case of corporeal substances. | |
| From: report of Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267]) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 5.2.3 | |
| A reaction: This is at least as good a proposal as their apatial location. There is more chance of reidentifying matter than of precisely reidentifying a spatial location. Two indistinguishable spheres remain the classic problem case (of Max Black, Idea 10195) |
| 11202 | It is by having essence that things exist [Aquinas] |
| Full Idea: It is by having essence that things exist. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.94) | |
| A reaction: Compare Idea 11199, which gives a fuller picture. This idea seems to suggest essence as the cause of existence, which sounds wrong. Perhaps essence is a necessary condition of existence, but it is necessary that nothing indeterminate can exist? |
| 11203 | Specific individual essence is defined by material, and generic essence is defined by form [Aquinas] |
| Full Idea: Specific essence differs from generic essence by being demarcated: individuals are demarcated within species by dimensionally defined material, but species within genus by a defining differentiation taken from the form. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.95) | |
| A reaction: It clearly won't be enough to define an individual just to define its material and its shape. The material might also be essential to the genus, as when defining fire. Probably not very helpful. |
| 11200 | The definition of a physical object must include the material as well as the form [Aquinas] |
| Full Idea: Form alone cannot be a composite substance's essence. For a thing's essence is expressed by its definition, and unless the definition of a physical substance included both form and material, the definition wouldn't differ from mathematical objects. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.93) | |
| A reaction: This is the sort of thoroughly sensible remark that you only get from the greatest philosophers. Minor philosophers fall in love with things like forms, and then try to use them to explain everything. |
| 11196 | Essence is something in common between the natures which sort things into categories [Aquinas] |
| Full Idea: Since being as belonging to a category expresses the 'isness' of things, and belongs to all ten Aristotelian categories, essence must be something all the natures that sort different beings into genera and species have in common. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.92) | |
| A reaction: I like this because it is the essence which does the sorting, not the sorting which defines the essence (which seems to me to be a deep and widespread confusion). |
| 11208 | A simple substance is its own essence [Aquinas] |
| Full Idea: A simple substance is its own essence. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.103) | |
| A reaction: Aquinas takes complex substances to have their essences in various ways, but this thought is the basis of all essence. Presumably the Greek word 'ousia' names the key ingredient. |
| 9362 | Necessary truths are those we will maintain no matter what [Lewis,CI] |
| Full Idea: Those laws and those laws only have necessary truth which we are prepared to maintain, no matter what. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.367) | |
| A reaction: This bold and simple claim has famously been torpedoed by a well-known counterexample - that virtually every human being will cling on to the proposition "dogs have at some time existed" no matter what, but it clearly isn't a necessary truth. |
| 9365 | We can maintain a priori principles come what may, but we can also change them [Lewis,CI] |
| Full Idea: The a priori contains principles which can be maintained in the face of all experience, representing the initiative of the mind. But they are subject to alteration on pragmatic grounds, if expanding experience shows their intellectual infelicity. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.373) | |
| A reaction: [compressed] This simply IS Quine's famous 'web of belief' picture, showing how firmly Quine is in the pragmatist tradition. Lewis treats a priori principles as a pragmatic toolkit, which can be refined to be more effective. Not implausible... |
| 11198 | Definition of essence makes things understandable [Aquinas] |
| Full Idea: It is definition of essence that makes things understandable. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.92) | |
| A reaction: The aim of philosophy is understanding, which is achieved by successful explanation. I totally agree with this Aristotelian view, so neatly summarised by Aquinas. |
| 9361 | We have to separate the mathematical from physical phenomena by abstraction [Lewis,CI] |
| Full Idea: Physical processes present us with phenomena in which the purely mathematical has to be separated out by abstraction. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.367) | |
| A reaction: This is the father of modal logic endorsing traditional abstractionism, it seems. He is also, though, endorsing the view that a priori knowledge is created by us, with pragmatic ends in view. |
| 11206 | The mind constructs complete attributions, based on the unified elements of the real world [Aquinas] |
| Full Idea: Attribution is something mind brings to completion by constructing propositional connections and disconnections, basing itself on real-world unity possessed by the things being attributed to one another. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.102) | |
| A reaction: This compromise story seems to me to be exactly right. I take it that we respond to the real joints of nature, but using thought and language which is riddled with convention. |
| 11207 | A cause can exist without its effect, but the effect cannot exist without its cause [Aquinas] |
| Full Idea: When things are so related that one causes the other to exist, the cause can exist without what it causes but not vice versa. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.103) | |
| A reaction: This is open to question, if causes are supposed to be sufficient for effects. Presumably Aquinas would support the view that if the cause had not been, the effect would not have happened. But the current idea indicates the priority relation. |
| 9363 | Science seeks classification which will discover laws, essences, and predictions [Lewis,CI] |
| Full Idea: The scientific search is for such classification as will make it possible to correlate appearance and behaviour, to discover law, to penetrate to the "essential nature" of things in order that behaviour may become predictable. | |
| From: C.I. Lewis (A Pragmatic Conception of the A Priori [1923], p.368) | |
| A reaction: Modern scientific essentialists no longer invoke scare quotes, and I think we should talk of the search for the 'mechanisms' which explain behaviour, but Lewis seems to have been sixty years ahead of his time. |