32 ideas
| 18450 | Philosophy has its own mode of death, by separating soul from body [Porphyry] |
| Full Idea: There is a double death. One, known by all men, consists in the separation of the body with the soul; the other, characteristic of philosophers, results in the separation of the soul from the body. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn9 3) |
| 8952 | We reach 'reflective equilibrium' when intuitions and theory completely align [Fisher] |
| Full Idea: A state of 'reflective equilibrium' is when our theory and our intuitions become completely aligned | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 12.IV) | |
| A reaction: [Rawls made this concept famous] This is a helpful concept in trying to spell out the ideal which is the dream of believers in 'pure reason' - that there is a goal in which everything comes right. The problem is when people have different intuitions! |
| 8943 | Three-valued logic says excluded middle and non-contradition are not tautologies [Fisher] |
| Full Idea: In three-valued logic (L3), neither the law of excluded middle (p or not-p), nor the law of non-contradiction (not(p and not-p)) will be tautologies. If p has the value 'indeterminate' then so will not-p. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 07.I) | |
| A reaction: I quite accept that the world is full of indeterminate propositions, and that excluded middle and non-contradiction can sometimes be uncertain, but I am reluctant to accept that what is being offered here should be called 'logic'. |
| 8945 | Fuzzy logic has many truth values, ranging in fractions from 0 to 1 [Fisher] |
| Full Idea: In fuzzy logic objects have properties to a greater or lesser degree, and truth values are given as fractions or decimals, ranging from 0 to 1. Not-p is defined as 1-p, and other formula are defined in terms of maxima and minima for sets. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 07.II) | |
| A reaction: The question seems to be whether this is actually logic, or a recasting of probability theory. Susan Haack attacks it. If logic is the study of how truth is preserved as we move between propositions, then 0 and 1 need a special status. |
| 8951 | Classical logic is: excluded middle, non-contradiction, contradictions imply all, disjunctive syllogism [Fisher] |
| Full Idea: For simplicity, we can say that 'classical logic' amounts to the truth of four sentences: 1) either p or not-p; 2) it is not the case that both p and not-p; 3) from p and not-p, infer q; 4) from p or q and not-p, infer q. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 12.I) | |
| A reaction: [She says there are many ways of specifying classical logic] Intuition suggests that 2 and 4 are rather hard to dispute, while 1 is ignoring some grey areas, and 3 is totally ridiculous. There is, of course, plenty of support for 3! |
| 8950 | Logic formalizes how we should reason, but it shouldn't determine whether we are realists [Fisher] |
| Full Idea: Even if one is inclined to be a realist about everything, it is hard to see why our logic should be the determiner. Logic is supposed to formalize how we ought to reason, but whether or not we should be realists is a matter of philosophy, not logic. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 09.I) | |
| A reaction: Nice to hear a logician saying this. I do not see why talk in terms of an object is a commitment to its existence. We can discuss the philosopher's stone, or Arthur's sword, or the Loch Ness monster, or gravitinos, with degrees of commitment. |
| 8946 | We could make our intuitions about heaps precise with a million-valued logic [Fisher] |
| Full Idea: We could construct a 1,000,000-valued logic that would allow our intuitions concerning a heap to vary exactly with the amount of sand in the heap. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008]) | |
| A reaction: Presumably only an infinite number of grains of sand would then produce a true heap, and even one grain would count as a bit of a heap, which must both be wrong, so I can't see this helping much. |
| 18451 | The presence of the incorporeal is only known by certain kinds of disposition [Porphyry] |
| Full Idea: Being everywhere and nowhere, the incorporeal, wherever it happens to be, betrays its presence only by a certain kind of disposition. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 4Enn3 21(20)) | |
| A reaction: There is a mystical or dualist view of fundamental powers, as the spiritual engine which drives passive physical nature. It's rubbish of course, but if powers are primitive in a naturalistic theory, it is not a view which can be refuted. |
| 18459 | Diversity arises from the power of unity [Porphyry] |
| Full Idea: Diversity is born of the development of the power of unity. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn5 42) | |
| A reaction: I doubt whether even Porphyry understood this, but we might say that once the principle of unification enters into nature, it will inevitably result in diversity. One all-embracing unity would be indiscernible. |
| 8944 | Vagueness can involve components (like baldness), or not (like boredom) [Fisher] |
| Full Idea: Vague terms come in at least two different kinds: those whose constituent parts come in discrete packets (bald, rich, red) and those that don't (beauty, boredom, niceness). | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 07.II) | |
| A reaction: The first group seem to be features of the external world, and the second all occur in the mind. Baldness may be vague, but presumably hairs are (on the whole) not. Nature doesn't care whether someone is actually 'bald' or not. |
| 8941 | We can't explain 'possibility' in terms of 'possible' worlds [Fisher] |
| Full Idea: Explaining 'it is possible that p' by saying p is true in at least one possible world doesn't get me very far. If I don't understand what possibility is, then appealing to possible worlds is not going to do me much good. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 06.III) | |
| A reaction: This seems so blatant that I assume friends of possible worlds will have addressed the problem. Note that you will also need to understand 'possible' to define necessity as 'true in all possible worlds'. Necessarily-p is not-possibly-not-p. |
| 8947 | If all truths are implied by a falsehood, then not-p might imply both q and not-q [Fisher] |
| Full Idea: If all truths are implied by a falsehood, then 'if there are no trees in the park then there is no shade' and 'if there are no trees in the park there is plenty of shade' both come out as true. Intuitively, though, the second one is false. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 08.I) | |
| A reaction: The rule that a falsehood implies all truths must be the weakest idea in classical logic, if it actually implies a contradiction. This means we must take an interest in relevance logics. |
| 8949 | In relevance logic, conditionals help information to flow from antecedent to consequent [Fisher] |
| Full Idea: A good account of relevance logic suggests that a conditional will be true when the flow of information is such that a conditional is the device that helps information to flow from the antecedent to the consequent. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 08.III) | |
| A reaction: Hm. 'If you are going out, you'll need an umbrella'. This passes on information about 'out', but also brings in new information. 'If you are going out, I'm leaving you'. What flows is an interpretation of the antecedent. Tricky. |
| 18452 | Memory is not conserved images, but reproduction of previous thought [Porphyry] |
| Full Idea: Memory does not consist in preserving images. It is a faculty of reproducing the conceptions with which our soul has been occupied. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 5Enn6 25(2)) |
| 18453 | Intelligence is aware of itself, so the intelligence is both the thinker and the thought [Porphyry] |
| Full Idea: Since intelligence is intelligible for intelligence, intelligence is its own object. ...Intelligence, therefore, is simultaneously thinker and thought, all that thinks and all that is thought. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 5Enn3 32(5-7)) | |
| A reaction: This is a bit of a problem for Descartes, if the Cogito is taken as offering evidence (thought) for the existence of a thinker ('I'). Porphyry implies that the separation Descartes requires is impossible. |
| 18462 | The soul is everywhere and nowhere in the body, and must be its cause [Porphyry] |
| Full Idea: The soul is neither a body, nor in the body, but is only the cause of the body, because she is simultaneously everywhere and nowhere in the body. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn5 43) | |
| A reaction: This is the rather bewildering phenomenology of consciousness which persuaded Descartes of dualism. |
| 18463 | Successful introspection reveals the substrate along with the object of thought [Porphyry] |
| Full Idea: He who by thought can penetrate within his own substance, and can thus acquire knowledge of it, finds himself in this actualisation of knowledge and consciousness, where the substrate that knows is identical with the object that is known. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn5 44) | |
| A reaction: It seems remarkably that this ability is confidently asserted by Porphyry, and flatly denied by Hume. Were they just different people, or were they looking for different things, or was one of them deluded? |
| 18458 | The soul is bound to matter by the force of its own disposition [Porphyry] |
| Full Idea: The individual soul, which declines towards matter, is bound to the matter by the form which her disposition has made her choose. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn4 39) | |
| A reaction: This sounds like the soul is boss over the matter, and yet the soul is 'made' to choose union with matter. The Universal Soul is seen by Porphyr as the controller of the situation. |
| 18464 | Justice is each person fulfilling his function [Porphyry] |
| Full Idea: Justice, as has been rightly said, consists in each one fulfilling his [authentic and proper] function. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn5 44) | |
| A reaction: This is presumably a direct reference to the theory in Plato's 'Republic'. It makes the connection between virtue and function which I take to be basic to virtue theory, giving it a naturalistic advantaged over other theories. |
| 18448 | We should avoid the pleasures of love, or at least, should not enact our dreams [Porphyry] |
| Full Idea: The pleasures of love will not even involuntarily be tasted, at least, she will not allow herself to be drawn beyond the lights of fancy that occur in dreams. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn2 I.4) | |
| A reaction: Presumably erotic dreams are only tolerated because not much can be done about them. This brings out the puritanism of neo-platonism. |
| 18444 | Civil virtues make us behave benevolently, and thereby unite citizens [Porphyry] |
| Full Idea: The object of the civil virtues is to make us benevolent in our dealings with our fellow-human beings, and are so-called because they unite citizens. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn2 I.1) | |
| A reaction: Modern commentators underestimate the close link between ancient virtue and citizenship. It is hard for one person to have much of a notion of virtue if they live on a desert island, beyond caring for personal health. |
| 18445 | Civil virtues control the passions, and make us conform to our nature [Porphyry] |
| Full Idea: The civil virtues moderate the passions; their object is to teach us to live in conformity with the laws of human nature. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn2 I.2) | |
| A reaction: The link with human nature is basic to virtue theory, but this proposal is rather too vague. Are passions not part of the laws of human nature? |
| 18446 | Purificatory virtues detach the soul completely from the passions [Porphyry] |
| Full Idea: The object of the 'purificatory' virtues is to detach the soul completely from the passions. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn2 I.4) | |
| A reaction: This is an aspect of virtue theory which doesn't appear in Aristotle. He is in favour of rational control of the passions, but not of totally abandoning them. The neo-platonists are much more puritanical. They seem to go against human nature. |
| 18447 | There are practical, purificatory, contemplative, and exemplary virtues [Porphyry] |
| Full Idea: The practical virtues make man virtuous; the purificatory virtues make man divine....; the contemplative virtues defiy; while the exemplary virtues make a man the parent of divinities. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn2 I.4) | |
| A reaction: I like the idea of the 'exemplary' virtues. I think an entire theory of morality could be built on the notion that we are all role-models for one another. |
| 18456 | Unified real existence is neither great nor small, though greatness and smallness participate in it [Porphyry] |
| Full Idea: By its identity and numerical unity, real existence is neither great nor small, neither very large nor very small, though it causes even greatest and smallest to participate in its nature. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn4 37(5)) | |
| A reaction: Note the platonic word 'participate' [metechein], suggesting that he is talking about the Form of Existence here. Note also that we have 'real' existence here, implying a lesser type of existence that participates in it. |
| 18454 | Time is the circular movement of the soul [Porphyry] |
| Full Idea: It is the circular movement of the soul that constitutes time, just as the permanence of intelligence in itself constitutes eternity. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 5Enn3 32(5-7)) | |
| A reaction: Plato loved circles. If you think time is subjective, this is trying to express your intuition. Personally I think it is nonsense |
| 18455 | Some think time is seen at rest, as well as in movement [Porphyry] |
| Full Idea: Some have believed that time manifested in rest as well as in movement. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 5Enn3 32(5-7)) | |
| A reaction: If you like this idea, you should see Shoemaker's lovely three-worlds thought experiment. |
| 18460 | God is nowhere, and hence everywhere [Porphyry] |
| Full Idea: The divinity is everywhere because it is nowhere. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn5 43) |
| 1515 | Pythagoreans believe it is absurd to seek for goodness anywhere except with the gods [Iamblichus] |
| Full Idea: The thinking behind Pythagorean philosophy is that people behave in an absurd fashion if they try to find any source for the good other than the gods. | |
| From: Iamblichus (Life of Pythagoras [c.290], 137) |
| 18461 | Everything existing proceeds from divinity, and is within divinity [Porphyry] |
| Full Idea: All things that possess or do not possess existence proceed from divinity, and are within divinity. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn5 43) | |
| A reaction: Nice to see Porphyry endorsing Meinongian objects. I doubt whether he counts as a pantheist, but this is a very pantheistic remark. |
| 18449 | Nature binds or detaches body to soul, but soul itself joins and detaches soul from body [Porphyry] |
| Full Idea: Nature binds the body to the soul, but it is the soul herself that has bound herself to the body. It, therefore, belongs to nature to detach the body from the soul, while it is the soul herself that detaches herself from the body. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 1Enn9 2) | |
| A reaction: Baffling. What happens if there is a conflict? I suppose either party can cancel the bargain, but who wins when they disagree? |
| 18457 | Individual souls are all connected, though distinct, and without dividing universal Soul [Porphyry] |
| Full Idea: Individual souls are distinct without being separated from each other, and without dividing the universal Soul into a number of parts; they are united to each other without becoming confused. | |
| From: Porphyry (Launching Points to the Realm of the Mind [c.280], 6Enn4 39) | |
| A reaction: This sounds like Jung's theory that there is a universal subconscious which links us all together. Taken literally, I assume it is nonsense. As an invitation to acknowledge how much we all have in common, it is a nice corrective to liberal individualism. |