31 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) |
| 10688 | 'Equivocation' is when terms do not mean the same thing in premises and conclusion [Beall/Restall] |
| Full Idea: 'Equivocation' is when the terms do not mean the same thing in the premises and in the conclusion. | |
| From: JC Beall / G Restall (Logical Consequence [2005], Intro) |
| 10690 | Formal logic is invariant under permutations, or devoid of content, or gives the norms for thought [Beall/Restall] |
| Full Idea: Logic is purely formal either when it is invariant under permutation of object (Tarski), or when it has totally abstracted away from all contents, or it is the constitutive norms for thought. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) | |
| A reaction: [compressed] The third account sounds rather woolly, and the second one sounds like a tricky operation, but the first one sounds clear and decisive, so I vote for Tarski. |
| 10691 | Logical consequence needs either proofs, or absence of counterexamples [Beall/Restall] |
| Full Idea: Technical work on logical consequence has either focused on proofs, where validity is the existence of a proof of the conclusions from the premises, or on models, which focus on the absence of counterexamples. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 10695 | Logical consequence is either necessary truth preservation, or preservation based on interpretation [Beall/Restall] |
| Full Idea: Two different views of logical consequence are necessary truth-preservation (based on modelling possible worlds; favoured by Realists), or truth-preservation based on the meanings of the logical vocabulary (differing in various models; for Anti-Realists). | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) | |
| A reaction: Thus Dummett prefers the second view, because the law of excluded middle is optional. My instincts are with the first one. |
| 10689 | A step is a 'material consequence' if we need contents as well as form [Beall/Restall] |
| Full Idea: A logical step is a 'material consequence' and not a formal one, if we need the contents as well as the structure or form. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) |
| 16974 | The nature of each logical concept is given by a collection of inference rules [Correia] |
| Full Idea: The view presented here presupposes that each logical concept is associated with some fixed and well defined collection of rules of inference which characterize its basic logical nature. | |
| From: Fabrice Correia (On the Reduction of Necessity to Essence [2012], 4) | |
| A reaction: [He gives Fine's 'Senses of Essences' 57-8 as a source] He seems to have in mind natural deduction, where the rules are for the introduction and elimination of the concepts. |
| 10696 | A 'logical truth' (or 'tautology', or 'theorem') follows from empty premises [Beall/Restall] |
| Full Idea: If a conclusion follows from an empty collection of premises, it is true by logic alone, and is a 'logical truth' (sometimes a 'tautology'), or, in the proof-centred approach, 'theorems'. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 4) | |
| A reaction: These truths are written as following from the empty set Φ. They are just implications derived from the axioms and the rules. |
| 10693 | Models are mathematical structures which interpret the non-logical primitives [Beall/Restall] |
| Full Idea: Models are abstract mathematical structures that provide possible interpretations for each of the non-logical primitives in a formal language. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 10692 | Hilbert proofs have simple rules and complex axioms, and natural deduction is the opposite [Beall/Restall] |
| Full Idea: There are many proof-systems, the main being Hilbert proofs (with simple rules and complex axioms), or natural deduction systems (with few axioms and many rules, and the rules constitute the meaning of the connectives). | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 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. |
| 16973 | Explain logical necessity by logical consequence, or the other way around? [Correia] |
| Full Idea: One view is that logical consequence is to be understood in terms of logical necessity (some proposition holds necessarily, if some group of other propositions holds). Alternatively, logical necessity is a logical consequence of the empty set. | |
| From: Fabrice Correia (On the Reduction of Necessity to Essence [2012], 3) | |
| A reaction: I think my Finean preference is for all necessities to have a 'necessitator', so logical necessity results from logic in some way, perhaps from logical consequence, or from the essences of the connectives and operators. |
| 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) |
| 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. |