22 ideas
1642 | We must fight fiercely for knowledge, understanding and intelligence [Plato] |
Full Idea: We need to use every argument we can to fight against anyone who does away with knowledge, understanding, and intelligence, but at the same time asserts anything at all about anything. | |
From: Plato (The Sophist [c.359 BCE], 249c) | |
A reaction: Thus showing that reason is only central if you want to put a high value on it? |
1645 | The desire to split everything into its parts is unpleasant and unphilosophical [Plato] |
Full Idea: To try to set apart everything from everything is not only especially jangling, but it is the mark of someone altogether unmusical and unphilosophic. | |
From: Plato (The Sophist [c.359 BCE], 259e) |
287 | Good analysis involves dividing things into appropriate forms without confusion [Plato] |
Full Idea: It takes expertise in dialectic to divide things by kinds and not to think that the same form is a different one or that a different form is the same. | |
From: Plato (The Sophist [c.359 BCE], 253d) |
1644 | Dialectic should only be taught to those who already philosophise well [Plato] |
Full Idea: The dialectical capacity - you won't give it to anyone else, I suspect, except to whoever philosophises purely and justly. | |
From: Plato (The Sophist [c.359 BCE], 253e) |
20478 | In discussion a person's opinions are shown to be in conflict, leading to calm self-criticism [Plato] |
Full Idea: They collect someone's opinions together during the discussion, put them side by side, and show that they conflict with each other at the same time on the same subjects.... The person sees this, gets angry at themselves, and calmer towards others. | |
From: Plato (The Sophist [c.359 BCE], 230b) | |
A reaction: He goes on to say that the process is like a doctor purging a patient of internal harms. If anyone talks for long enough (even a good philosopher), their opinions will probably be seen to be in conflict. But which opinions do you abandon? |
11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
From: Ian Rumfitt ("Yes" and "No" [2000]) | |
A reaction: This is the standard view which Rumfitt sets out to challenge. |
11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
11278 | What does 'that which is not' refer to? [Plato] |
Full Idea: What should the name 'that which is not' be applied to? | |
From: Plato (The Sophist [c.359 BCE], 237c) | |
A reaction: This leads into a discussion of the problem, in The Sophist. It became a large issue when modern logic was being developed by Frege and Russell. |
1643 | If statements about non-existence are logically puzzling, so are statements about existence [Plato] |
Full Idea: When the question was put to us as to the name of 'that which is not', to whatever one must apply it, we got stuck in every kind of perplexity. Are we now in any less perplexity about 'that which is'? | |
From: Plato (The Sophist [c.359 BCE], 250d) | |
A reaction: Nice. This precapitulates the whole story of modern philosophy of language. What started as a nagging doubt about reference to non-existents ends as bewilderment about everything we say. |
7022 | To be is to have a capacity, to act on other things, or to receive actions [Plato] |
Full Idea: A thing really is if it has any capacity, either by nature to do something to something else or to have even the smallest thing done to it by the most trivial thing, even if it only happens once. I'll define those which are as nothing other than capacity. | |
From: Plato (The Sophist [c.359 BCE], 247e) | |
A reaction: If philosophy is footnotes to Plato, this should be the foundational remark in all discussions of existence (though Parmenides might claim priority). It seems to say 'to be is to have a causal role (active or passive)'. It also seems essentialist. |
1641 | Some alarming thinkers think that only things which you can touch exist [Plato] |
Full Idea: One group drags everything down to earth, insisting that only what offers tangible contact is, since they define being as the same as body, despising anyone who says that something without a body is. These are frightening men. | |
From: Plato (The Sophist [c.359 BCE], 246b) |
10784 | Whenever there's speech it has to be about something [Plato] |
Full Idea: Whenever there's speech it has to be about something. It's impossible for it not to be about something. | |
From: Plato (The Sophist [c.359 BCE], 262e) | |
A reaction: [Quoted by Marcus about ontological commitment] The interesting test case would be speech about the existence of circular squares. |
13095 | Essence is primitive force, or a law of change [Leibniz] |
Full Idea: The essence of substances consists in the primitive force of action, or the law of the sequence of changes. | |
From: Gottfried Leibniz (Letters to Foucher [1675], 1676) | |
A reaction: [a 1676 note on Foucher's reply] It take these to be the two key distinctive Leibnizian contributions to the sort of metaphysic that is needed by modern science. Nature works with intrinsic essences, which are forces determining action. |
16122 | Good thinkers spot forms spread through things, or included within some larger form [Plato] |
Full Idea: It takes dialectic to divide things by kinds...such a person can discriminate a single form spread through a lot of separate things…and forms included in a single outside form…or a form connected as a unit through many wholes. | |
From: Plato (The Sophist [c.359 BCE], 253d) | |
A reaction: [compressed] This is very helpful in indicating the complex structure of the Forms that Plato envisages. If you talk of the meanings of words (other than names), though, it comes to the same thing. Wise people fully understand their language. |
10422 | The not-beautiful is part of the beautiful, though opposed to it, and is just as real [Plato] |
Full Idea: So 'the not beautiful' turns out to be ..both marked off within one kind of those that are, and also set over against one of those that are, ..and the beautiful is no more a being than the not beautiful. | |
From: Plato (The Sophist [c.359 BCE], 257d) | |
A reaction: [dialogue eliminated] This is a highly significant passage, for two reasons. It suggests that the Form of the beautiful can have parts, and also that the negations of Forms are Forms themselves (both of which come as a surprise). |
15855 | If we see everything as separate, we can then give no account of it [Plato] |
Full Idea: To dissociate each thing from everything else is to destroy totally everything there is to say. The weaving together of forms is what makes speech [logos] possible for us. | |
From: Plato (The Sophist [c.359 BCE], 259e) | |
A reaction: This I take to be the lynchpin of metaphysics. We are forced to see the world in a way which enables us to give some sort of account of it. Our metaphysics is 'inference to the best logos'. |
1637 | A soul without understanding is ugly [Plato] |
Full Idea: The soul that lacks understanding must be set down as ugly. | |
From: Plato (The Sophist [c.359 BCE], 228d) | |
A reaction: The teleological view of things understands their nature in things of their perfection. and the essence of beauty is perfection. It is the mind's nature to know. Failing to know is as ugly as allowing your crops to die. |
11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |
1636 | Wickedness is an illness of the soul [Plato] |
Full Idea: Wickedness is a sedition and illness of the soul. | |
From: Plato (The Sophist [c.359 BCE], 228b) |
1638 | Didactic education is hard work and achieves little [Plato] |
Full Idea: With a lot of effort the admonitory species of education accomplishes little. | |
From: Plato (The Sophist [c.359 BCE], 230a) |
2117 | The connection in events enables us to successfully predict the future, so there must be a constant cause [Leibniz] |
Full Idea: There is a connection among our appearances that provides us the means to predict future appearances with success, and this connection must have a constant cause. | |
From: Gottfried Leibniz (Letters to Foucher [1675]) |