52 ideas
| 2056 | Philosophers are always switching direction to something more interesting [Plato] |
| Full Idea: Philosophers are always ready to change direction, if a topic crops up which is more attractive than the one to hand. | |
| From: Plato (Theaetetus [c.368 BCE], 172d) | |
| A reaction: Which sounds trivial, but it may be what God does. |
| 2086 | Understanding mainly involves knowing the elements, not their combinations [Plato] |
| Full Idea: A perfect grasp of any subject depends far more on knowing elements than on knowing complexes. | |
| From: Plato (Theaetetus [c.368 BCE], 206b) |
| 2083 | Either a syllable is its letters (making parts as knowable as whole) or it isn't (meaning it has no parts) [Plato] |
| Full Idea: Either a syllable is not the same as its letters, in which case it cannot have the letters as parts of itself, or it is the same as its letters, in which case these basic elements are just as knowable as it is. | |
| From: Plato (Theaetetus [c.368 BCE], 205b) |
| 2082 | A rational account is essentially a weaving together of things with names [Plato] |
| Full Idea: Just as primary elements are woven together, so their names may be woven together to produce a spoken account, because an account is essentially a weaving together of names. | |
| From: Plato (Theaetetus [c.368 BCE], 202b) | |
| A reaction: If justification requires 'logos', and logos is a 'weaving together of names', then Plato might be taken as endorsing the coherence account of justification. Or do the two 'weavings' correspond? |
| 4643 | The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations [Baggini /Fosl] |
| Full Idea: The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.28) | |
| A reaction: This sounds a reasonable note of caution, but doesn't carry much weight unless some type of non-causal reason can be envisaged. God's free will? Our free will? The laws of causation? |
| 4633 | You cannot rationally deny the principle of non-contradiction, because all reasoning requires it [Baggini /Fosl] |
| Full Idea: Anyone who denies the principle of non-contradiction simultaneously affirms it; it cannot be rationally criticised, because it is presupposed by all rationality. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.12) | |
| A reaction: Nietzsche certainly wasn't afraid to ask why we should reject something because it is a contradiction. The 'logic of personal advantage' might allow logical contradictions. |
| 4635 | Dialectic aims at unified truth, unlike analysis, which divides into parts [Baggini /Fosl] |
| Full Idea: Dialectic can be said to aim at wholeness or unity, while 'analytic' thinking divides that with which it deals into parts. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.03) | |
| A reaction: I don't accept this division (linked here to Hegel). I am a fan of analysis, as practised by Aristotle, but it is like dismantling an engine to identify and clean the parts, before reassembling it more efficiently. |
| 2052 | Eristic discussion is aggressive, but dialectic aims to help one's companions in discussion [Plato] |
| Full Idea: Eristic discussions involve as many tricks and traps as possible, but dialectical discussions involve being serious and correcting the interlocutor's mistakes only when they are his own fault or the result of past conditioning. | |
| From: Plato (Theaetetus [c.368 BCE], 167e) |
| 15854 | A primary element has only a name, and no logos, but complexes have an account, by weaving the names [Plato] |
| Full Idea: A primary element cannot be expressed in an account; it can only be named, for a name is all that it has. But with the things composed of these ...just as the elements are woven together, so the names can woven to become an account. | |
| From: Plato (Theaetetus [c.368 BCE], 202b01-3) | |
| A reaction: This is the beginning of what I see as Aristotle's metaphysics, as derived from his epistemology, that is, ontology is what explains, and what we can give an account [logos] of. Aristotle treats this under 'definitions'. |
| 4632 | 'Natural' systems of deduction are based on normal rational practice, rather than on axioms [Baggini /Fosl] |
| Full Idea: A 'natural' system of deduction does not posit any axioms, but looks instead for its formulae to the practices of ordinary rationality. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.09) | |
| A reaction: Presumably there is some middle ground, where we attempt to infer the axioms of normal practice, and then build a strict system on them. We must be allowed to criticise 'normal' rationality, I hope. |
| 4631 | In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use [Baggini /Fosl] |
| Full Idea: In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.09) | |
| A reaction: Yes, but the trouble is that all our notions of 'rational' (giving reasons, being consistent) break down when we look at unsupported axioms. In what sense is something rational if it is self-evident? |
| 4638 | The principle of bivalence distorts reality, as when claiming that a person is or is not 'thin' [Baggini /Fosl] |
| Full Idea: Forcing everything into the straightjacket of bivalence seriously distorts the world. The problem is most acute in the case of vague concepts, such as thinness. It is not straightforwardly true or false that a person is thin. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.03) | |
| A reaction: Can't argue with that. Can we divide all our concepts into either bivalent or vague? Presumably both propositions and concepts could be bivalent. |
| 10216 | We master arithmetic by knowing all the numbers in our soul [Plato] |
| Full Idea: It must surely be true that a man who has completely mastered arithmetic knows all numbers? Because there are pieces of knowledge covering all numbers in his soul. | |
| From: Plato (Theaetetus [c.368 BCE], 198b) | |
| A reaction: This clearly views numbers as objects. Expectation of knowing them all is a bit startling! They also appear to be innate in us, and hence they appear to be Forms. See Aristotle's comment in Idea 645. |
| 2060 | There seem to be two sorts of change: alteration and motion [Plato] |
| Full Idea: There are two kinds of change, I think: alteration and motion. | |
| From: Plato (Theaetetus [c.368 BCE], 181d) |
| 2084 | If a word has no parts and has a single identity, it turns out to be the same kind of thing as a letter [Plato] |
| Full Idea: If a complex or a syllable has no parts and is a single identity, hasn't it turned out to be the same kind of thing as an element or letter? | |
| From: Plato (Theaetetus [c.368 BCE], 205d) |
| 15844 | A sum is that from which nothing is lacking, which is a whole [Plato] |
| Full Idea: But this sum now - isn't it just when there is nothing lacking that it is a sum? Yes, necessarily. And won't this very same thing - that from which nothing is lacking - be a whole? | |
| From: Plato (Theaetetus [c.368 BCE], 205a) | |
| A reaction: This seems to be right, be rather too vague and potentially circular to be of much use. What is the criterion for deciding that nothing is lacking? |
| 15843 | The whole can't be the parts, because it would be all of the parts, which is the whole [Plato] |
| Full Idea: The whole does not consist of parts; for it did, it would be all the parts and so would be the sum. | |
| From: Plato (Theaetetus [c.368 BCE], 204e) | |
| A reaction: That is, 'the whole is the sum of its parts' is a tautology! The claim that 'the whole is more than the sum of its parts' gets into similar trouble. See Verity Harte on this. |
| 4640 | If identity is based on 'true of X' instead of 'property of X' we get the Masked Man fallacy ('I know X but not Y') [Baggini /Fosl, by PG] |
| Full Idea: The Masked Man fallacy is when Leibniz's Law is taken as 'X and Y are identical if what is true of X is true of Y' (rather than being about properties). Then 'I know X' but 'I don't know Y' (e.g. my friend wearing a mask) would make X and Y non-identical. | |
| From: report of J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.17) by PG - Db (ideas) | |
| A reaction: As the book goes on to explain, Descartes is guilty of this when arguing that I necessarily know my mind but not my body, so they are different. Seems to me that Kripke falls into the same trap. |
| 4647 | 'I have the same car as you' is fine; 'I have the same fiancée as you' is not so good [Baggini /Fosl] |
| Full Idea: If you found that I had the same car as you, I don't suppose you would care, but if you found I had the same fiancée as you, you might not be so happy. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.17) | |
| A reaction: A very nice illustration of the ambiguity of "same", and hence of identity. 'I had the same thought as you'. 'I have the same DNA as you'. |
| 4639 | Leibniz's Law is about the properties of objects; the Identity of Indiscernibles is about perception of objects [Baggini /Fosl] |
| Full Idea: Leibniz's Law ('if identical, must have same properties') defines identity according to the properties possessed by the object itself, but the Identity of Indiscernibles defines identity in terms of how things are conceived or grasped by the mind. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.16) | |
| A reaction: This is the heart of the problem of identity. We realists must fight for Leibniz's Law, and escort the Identity of Indiscernibles to the door. |
| 4646 | Is 'events have causes' analytic a priori, synthetic a posteriori, or synthetic a priori? [Baggini /Fosl] |
| Full Idea: Of the proposition that "all experienced events have causes", Descartes says this is analytic a priori, Hume says it is synthetic a posteriori, and Kant says it is synthetic a priori. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.01) | |
| A reaction: I am not sympathetic to Hume on this (though most people think he is right). I prefer the Kantian view, but he makes a very large claim. Something has to be intuitive. |
| 2080 | Things are only knowable if a rational account (logos) is possible [Plato] |
| Full Idea: Things which are susceptible to a rational account are knowable. | |
| From: Plato (Theaetetus [c.368 BCE], 201d) |
| 16126 | Expertise is knowledge of the whole by means of the parts [Plato] |
| Full Idea: A man has passed from mere judgment to expert knowledge of the being of a wagon when he has done so in virtue of having gone over the whole by means of the elements. | |
| From: Plato (Theaetetus [c.368 BCE], 207c) | |
| A reaction: Plato is emphasising that the expert must know the hundred parts of a wagon, and not just the half dozen main components, but here the point is to go over the whole via the parts, and not just list the parts. |
| 2050 | It is impossible to believe something which is held to be false [Plato] |
| Full Idea: It is impossible to believe something which is not the case. | |
| From: Plato (Theaetetus [c.368 BCE], 167a) |
| 2076 | How can a belief exist if its object doesn't exist? [Plato] |
| Full Idea: If the object of a belief is what is not, the object of this belief is nothing; but if there is no object to a belief, then that is not belief at all. | |
| From: Plato (Theaetetus [c.368 BCE], 189a) |
| 4645 | 'A priori' does not concern how you learn a proposition, but how you show whether it is true or false [Baggini /Fosl] |
| Full Idea: What makes something a priori is not the means by which it came to be known, but the means by which it can be shown to be true or false. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §4.01) | |
| A reaction: Helpful. Kripke in particular has labelled the notion as an epistemological one, but that does imply a method of acquiring it. Clearly I can learn an a priori truth by reading it the newspaper. |
| 2045 | Perception is infallible, suggesting that it is knowledge [Plato] |
| Full Idea: Perception is always of something that is, and it is infallible, which suggests that it is knowledge. | |
| From: Plato (Theaetetus [c.368 BCE], 152c) |
| 2067 | Our senses could have been separate, but they converge on one mind [Plato] |
| Full Idea: It would be peculiar if each of us were like a Trojan horse, with a whole bunch of senses sitting inside us, rather than that all these perceptions converge onto a single identity (mind, or whatever one ought to call it). | |
| From: Plato (Theaetetus [c.368 BCE], 184d) |
| 2068 | With what physical faculty do we perceive pairs of opposed abstract qualities? [Plato] |
| Full Idea: With what physical faculty do we perceive being and not-being, similarity and dissimilarity, identity and difference, oneness and many, odd and even and other maths, ….fineness and goodness? | |
| From: Plato (Theaetetus [c.368 BCE], 185d) |
| 2078 | You might mistake eleven for twelve in your senses, but not in your mind [Plato] |
| Full Idea: Sight or touch might make someone take eleven for twelve, but he could never form this mistaken belief about the contents of his mind. | |
| From: Plato (Theaetetus [c.368 BCE], 195e) |
| 2069 | Thought must grasp being itself before truth becomes possible [Plato] |
| Full Idea: If you can't apprehend being you can't apprehend truth, and so a thing could not be known. Therefore knowledge is not located in immediate experience but in thinking about it, since the latter makes it possible to grasp being and truth. | |
| From: Plato (Theaetetus [c.368 BCE], 186c) |
| 2089 | An inadequate rational account would still not justify knowledge [Plato] |
| Full Idea: If you don't know which letters belong together in the right syllables…it is possible for true belief to be accompanied by a rational account and still not be entitled to the name of knowledge. | |
| From: Plato (Theaetetus [c.368 BCE], 208b) | |
| A reaction: In each case of justification there is a 'clinching' stage, for which there is never going to be a strict rule. It might be foundational, but equally it might be massive coherence, or no alternative. |
| 2085 | Parts and wholes are either equally knowable or equally unknowable [Plato] |
| Full Idea: Either a syllable and its letters are equally knowable and expressible in a rational account, or they are both equally unknowable and inexpressible. | |
| From: Plato (Theaetetus [c.368 BCE], 205e) | |
| A reaction: Presumably you could explain the syllable by the letters, but not vice versa, but he must mean that the explanation is worthless without the letters being explained too. So all explanation is worthless? |
| 2091 | Without distinguishing marks, how do I know what my beliefs are about? [Plato] |
| Full Idea: If I only have beliefs about Theaetetus when I don't know his distinguishing mark, how on earth were my beliefs about you rather than anyone else? | |
| From: Plato (Theaetetus [c.368 BCE], 209b) | |
| A reaction: This is a rather intellectualist approach to mental activity. Presumably Theaetetus has lots of distinguishing marks, but they are not conscious. Must Socrates know everything? |
| 2087 | A rational account might be seeing an image of one's belief, like a reflection in a mirror [Plato] |
| Full Idea: A rational account might be forming an image of one's belief, as in a mirror or a pond. | |
| From: Plato (Theaetetus [c.368 BCE], 206d) | |
| A reaction: Not promising, since the image is not going to be clearer than the original, or contain any new information. Maybe it would be clarified by being 'framed', instead of drifting in muddle. |
| 2090 | A rational account involves giving an image, or analysis, or giving a differentiating mark [Plato] |
| Full Idea: A third sort of rational account (after giving an image, or analysing elements) is being able to mention some mark which differentiates the object in question ('the sun is the brightest heavenly body'). | |
| From: Plato (Theaetetus [c.368 BCE], 208c) | |
| A reaction: This is Plato's clearest statement of what would be involved in adding the necessary logos to your true belief. An image of it, or an analysis, or an individuation. How about a cause? |
| 2081 | Maybe primary elements can be named, but not receive a rational account [Plato] |
| Full Idea: Maybe the primary elements of which things are composed are not susceptible to rational accounts. Each of them taken by itself can only be named, but nothing further can be said about it. | |
| From: Plato (Theaetetus [c.368 BCE], 201e) | |
| A reaction: This still seems to be more or less the central issue in philosophy - which things should be treated as 'primitive', and which other things are analysed and explained using the primitive tools? |
| 4582 | Basic beliefs are self-evident, or sensual, or intuitive, or revealed, or guaranteed [Baggini /Fosl] |
| Full Idea: Sentence are held to be basic because they are self-evident or 'cataleptic' (Stoics), or rooted in sense data (positivists), or grasped by intuition (Platonists), or revealed by God, or grasped by faculties certified by God (Descartes). | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.01) | |
| A reaction: These are a bit blurred. Isn't intuition self-evident? Isn't divine guarantee a type of revelation? How about reason, experience or authority? |
| 2088 | A rational account of a wagon would mean knowledge of its hundred parts [Plato] |
| Full Idea: In the case of a wagon, we may only have correct belief, but someone who is able to explain what it is by going through its hundred parts has got hold of a rational account. | |
| From: Plato (Theaetetus [c.368 BCE], 207b) | |
| A reaction: A wonderful example. In science, you know smoking correlates with cancer, but you only know it when you know the mechanism, the causal structure. This may be a general truth. |
| 2047 | What evidence can be brought to show whether we are dreaming or not? [Plato] |
| Full Idea: What evidence could be brought if we were asked at this very moment whether we are asleep and are dreaming all our thoughts? | |
| From: Plato (Theaetetus [c.368 BCE], 158b) |
| 2053 | If you claim that all beliefs are true, that includes beliefs opposed to your own [Plato] |
| Full Idea: To say that everyone believes what is the case, is to concede the truth of the oppositions' beliefs; in other words, the person has to concede that he himself is wrong. | |
| From: Plato (Theaetetus [c.368 BCE], 171a) |
| 2059 | How can a relativist form opinions about what will happen in the future? [Plato] |
| Full Idea: Does a relativist have any authority to decide about things which will happen in the future? | |
| From: Plato (Theaetetus [c.368 BCE], 178c) | |
| A reaction: Nice question! It seems commonsense that such speculations are possible, but without a concept of truth they are ridiculous. |
| 2054 | Clearly some people are superior to others when it comes to medicine [Plato] |
| Full Idea: In medicine, at least, most people are not self-sufficient at prescribing and effecting cures for themselves, and here some people are superior to others. | |
| From: Plato (Theaetetus [c.368 BCE], 171e) |
| 4644 | A proposition such as 'some swans are purple' cannot be falsified, only verified [Baggini /Fosl] |
| Full Idea: The problem with falsification is that it fails to work with logically particular claims such as 'some swans are purple'. Examining a million swans and finding no purple ones does not falsify the claim, as there might still be a purple swan out there. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.29) | |
| A reaction: Isn't it beautiful how unease about a theory (Popper's) slowly crystallises into an incredibly simple and devastating point? Maybe 'some swans are purple' isn't science unless there is a good reason to propose it? |
| 4584 | The problem of induction is how to justify our belief in the uniformity of nature [Baggini /Fosl] |
| Full Idea: At its simplest, the problem of induction can be boiled down to the problem of justifying our belief in the uniformity of nature. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.03) | |
| A reaction: An easy solution to the problem of induction: we treat the uniformity of nature as axiomatic, and then induction is all reasoning which is based on that axiom. The axiom is a working hypothesis, which may begin to appear false. Anomalies are hard. |
| 4583 | How can an argument be good induction, but poor deduction? [Baggini /Fosl] |
| Full Idea: The problem of induction is the problem of how an argument can be good reasoning as induction but poor reasoning as deduction. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.03) | |
| A reaction: Nicely put, and a good defence of Hume against the charge that he has just muddled induction and deduction. All reasoning, we insist, should be consistent, or it isn't reasoning. |
| 4634 | Abduction aims at simplicity, testability, coherence and comprehensiveness [Baggini /Fosl] |
| Full Idea: There are some 'principles of selection' in abduction: 1) prefer simple explanations, 2) prefer coherent explanations (consistent with what is already held true), 3) prefer theories that make testable predictions, and 4) be comprehensive in scope. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §2.01) | |
| A reaction: Note that these are desirable, but not necessary (pace Ockham and Ayer). I cannot think of anything to add to the list, so I will adopt it. Abduction is the key to rationality. |
| 4637 | To see if an explanation is the best, it is necessary to investigate the alternative explanations [Baggini /Fosl] |
| Full Idea: The only way to be sure we have the best explanation is to investigate the alternatives and see if they are any better. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §3.01) | |
| A reaction: Unavoidable! Since I love 'best explanation', I now seem to be committed to investigation every mad theory that comes up, just in case it is better. I hope I am allowed to reject after a very quick sniff. |
| 4629 | Consistency is the cornerstone of rationality [Baggini /Fosl] |
| Full Idea: Consistency is the cornerstone of rationality. | |
| From: J Baggini / PS Fosl (The Philosopher's Toolkit [2003], §1.06) | |
| A reaction: This is right, and is a cornerstone of Kant's approach to ethics. Rational beings must follow principles - in order to be consistent in their behaviour. 'Consistent' now requires a definition…. |
| 11911 | Some philosophers always want more from morality; for others, nature is enough [Blackburn] |
| Full Idea: The history of moral theory is largely a history of battles between people who want more (truth, absolutes...) - Plato, Locke, Cudworth, Kant, Nagel - and people content with what we have (nature) - Aristotle, Epicurus, Hobbes, Hume, Stevenson. | |
| From: Simon Blackburn (Précis of 'Ruling Passions' [2002], p.133) | |
| A reaction: [Thanks to Neil Sinclair for this one] As a devotee of Aristotle, I like this. I'm always impressed, though, by people who go the extra mile in morality, because they are in the grips of purer and loftier ideals than I am. They also turn into monsters! |
| 2058 | God must be the epitome of goodness, and we can only approach a divine state by being as good as possible [Plato] |
| Full Idea: It is impossible for God to be immoral and not to be the acme of morality; and the only way any of us can approximate to God is to become as moral as possible. | |
| From: Plato (Theaetetus [c.368 BCE], 176c) |
| 2057 | There must always be some force of evil ranged against good [Plato] |
| Full Idea: The elimination of evil is impossible, Theodorus; there must always be some force ranged against good. | |
| From: Plato (Theaetetus [c.368 BCE], 176a) |