46 ideas
| 5896 | Speak the truth, for this alone deifies man [Pythagoras, by Porphyry] |
| Full Idea: Pythagoras advised above all things to speak the truth, for this alone deifies man. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Porphyry - Life of Pythagoras §41 | |
| A reaction: Idea 4421 (of Nietzsche) stands in contrast to this. I am not quite sure why speaking the truth has such a high value. I am inclined to a minimalist view, which is just that philosophy is an attempt to speak the truth, as fishermen try to catch fish. |
| 9247 | Life will be lived better if it has no meaning [Camus] |
| Full Idea: Life will be lived all the better if it has no meaning. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs free') | |
| A reaction: One image of the good life is that of a successful wild animal, for which existence is not a problem, merely a constant activity and pursuit. Maybe life begins to acquire meaning once we realise that meaning should not be sought directly. |
| 3051 | Pythagoras discovered the numerical relation of sounds on a string [Pythagoras, by Diog. Laertius] |
| Full Idea: Pythagoras discovered the numerical relation of sounds on a string. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 08.1.11 |
| 6707 | Suicide - whether life is worth living - is the one serious philosophical problem [Camus] |
| Full Idea: There is but one truly serious philosophical problem and that is suicide. Judgine whether life is or is not worth living amounts to answering the fundamental question of philosophy. | |
| From: Albert Camus (The Myth of Sisyphus [1942], p.11) | |
| A reaction: What a wonderful thesis for a book. In Idea 2682 there is the possibility of life being worth living, but not worth a huge amount of effort. It is better to call Camus' question the first question, rather than the only question. |
| 9245 | To an absurd mind reason is useless, and there is nothing beyond reason [Camus] |
| Full Idea: To an absurd mind reason is useless, and there is nothing beyond reason. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Phil Suic') | |
| A reaction: But there is, surely, intuition and instinct? Read Keats's Letters. There is good living through upbringing and habit. Read Aristotle. If you like Camus' thought, you will love Chuang Tzu. Personally I am a child of the Enlightenment. |
| 17926 | Rejecting double negation elimination undermines reductio proofs [Colyvan] |
| Full Idea: The intuitionist rejection of double negation elimination undermines the important reductio ad absurdum proof in classical mathematics. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) |
| 17925 | Showing a disproof is impossible is not a proof, so don't eliminate double negation [Colyvan] |
| Full Idea: In intuitionist logic double negation elimination fails. After all, proving that there is no proof that there can't be a proof of S is not the same thing as having a proof of S. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) | |
| A reaction: I do like people like Colyvan who explain things clearly. All of this difficult stuff is understandable, if only someone makes the effort to explain it properly. |
| 9244 | Logic is easy, but what about logic to the point of death? [Camus] |
| Full Idea: It is always easy to be logical. It is almost impossible to be logical to the bitter end. The only problem that interests me is: is there a logic to the point of death? | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs and Suic') | |
| A reaction: This is a lovely hand grenade to lob into an analytical logic class! It is very hard to get logicians to actually ascribe a clear value to their activity. They tend to present it as a marginal private game, and yet it has high status. |
| 17924 | Excluded middle says P or not-P; bivalence says P is either true or false [Colyvan] |
| Full Idea: The law of excluded middle (for every proposition P, either P or not-P) must be carefully distinguished from its semantic counterpart bivalence, that every proposition is either true or false. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) | |
| A reaction: So excluded middle makes no reference to the actual truth or falsity of P. It merely says P excludes not-P, and vice versa. |
| 17929 | Löwenheim proved his result for a first-order sentence, and Skolem generalised it [Colyvan] |
| Full Idea: Löwenheim proved that if a first-order sentence has a model at all, it has a countable model. ...Skolem generalised this result to systems of first-order sentences. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 2.1.2) |
| 17930 | Axioms are 'categorical' if all of their models are isomorphic [Colyvan] |
| Full Idea: A set of axioms is said to be 'categorical' if all models of the axioms in question are isomorphic. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 2.1.2) | |
| A reaction: The best example is the Peano Axioms, which are 'true up to isomorphism'. Set theory axioms are only 'quasi-isomorphic'. |
| 17928 | Ordinal numbers represent order relations [Colyvan] |
| Full Idea: Ordinal numbers represent order relations. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.2.3 n17) |
| 7485 | For Pythagoreans 'one' is not a number, but the foundation of numbers [Pythagoras, by Watson] |
| Full Idea: For Pythagoreans, one, 1, is not a true number but the 'essence' of number, out of which the number system emerges. | |
| From: report of Pythagoras (reports [c.530 BCE], Ch.8) by Peter Watson - Ideas Ch.8 | |
| A reaction: I think this is right! Counting and numbers only arise once the concept of individuality and identity have arisen. Counting to one is no more than observing the law of identity. 'Two' is the big adventure. |
| 17923 | Intuitionists only accept a few safe infinities [Colyvan] |
| Full Idea: For intuitionists, all but the smallest, most well-behaved infinities are rejected. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) | |
| A reaction: The intuitionist idea is to only accept what can be clearly constructed or proved. |
| 17941 | Infinitesimals were sometimes zero, and sometimes close to zero [Colyvan] |
| Full Idea: The problem with infinitesimals is that in some places they behaved like real numbers close to zero but in other places they behaved like zero. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 7.1.2) | |
| A reaction: Colyvan gives an example, of differentiating a polynomial. |
| 17922 | Reducing real numbers to rationals suggested arithmetic as the foundation of maths [Colyvan] |
| Full Idea: Given Dedekind's reduction of real numbers to sequences of rational numbers, and other known reductions in mathematics, it was tempting to see basic arithmetic as the foundation of mathematics. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.1) | |
| A reaction: The reduction is the famous Dedekind 'cut'. Nowadays theorists seem to be more abstract (Category Theory, for example) instead of reductionist. |
| 17936 | Transfinite induction moves from all cases, up to the limit ordinal [Colyvan] |
| Full Idea: Transfinite inductions are inductive proofs that include an extra step to show that if the statement holds for all cases less than some limit ordinal, the statement also holds for the limit ordinal. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1 n11) |
| 17940 | Most mathematical proofs are using set theory, but without saying so [Colyvan] |
| Full Idea: Most mathematical proofs, outside of set theory, do not explicitly state the set theory being employed. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 7.1.1) |
| 17931 | Structuralism say only 'up to isomorphism' matters because that is all there is to it [Colyvan] |
| Full Idea: Structuralism is able to explain why mathematicians are typically only interested in describing the objects they study up to isomorphism - for that is all there is to describe. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 3.1.2) |
| 17932 | If 'in re' structures relies on the world, does the world contain rich enough structures? [Colyvan] |
| Full Idea: In re structuralism does not posit anything other than the kinds of structures that are in fact found in the world. ...The problem is that the world may not provide rich enough structures for the mathematics. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 3.1.2) | |
| A reaction: You can perceive a repeating pattern in the world, without any interest in how far the repetitions extend. |
| 17943 | Probability supports Bayesianism better as degrees of belief than as ratios of frequencies [Colyvan] |
| Full Idea: Those who see probabilities as ratios of frequencies can't use Bayes's Theorem if there is no objective prior probability. Those who accept prior probabilities tend to opt for a subjectivist account, where probabilities are degrees of belief. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 9.1.8) | |
| A reaction: [compressed] |
| 17939 | Mathematics can reveal structural similarities in diverse systems [Colyvan] |
| Full Idea: Mathematics can demonstrate structural similarities between systems (e.g. missing population periods and the gaps in the rings of Saturn). | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 6.3.2) | |
| A reaction: [Colyvan expounds the details of his two examples] It is these sorts of results that get people enthusiastic about the mathematics embedded in nature. A misunderstanding, I think. |
| 17938 | Mathematics can show why some surprising events have to occur [Colyvan] |
| Full Idea: Mathematics can show that under a broad range of conditions, something initially surprising must occur (e.g. the hexagonal structure of honeycomb). | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 6.3.2) |
| 17934 | Proof by cases (by 'exhaustion') is said to be unexplanatory [Colyvan] |
| Full Idea: Another style of proof often cited as unexplanatory are brute-force methods such as proof by cases (or proof by exhaustion). | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1) |
| 17933 | Reductio proofs do not seem to be very explanatory [Colyvan] |
| Full Idea: One kind of proof that is thought to be unexplanatory is the 'reductio' proof. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1) | |
| A reaction: Presumably you generate a contradiction, but are given no indication of why the contradiction has arisen? Tracking back might reveal the source of the problem? Colyvan thinks reductio can be explanatory. |
| 17935 | If inductive proofs hold because of the structure of natural numbers, they may explain theorems [Colyvan] |
| Full Idea: It might be argued that any proof by induction is revealing the explanation of the theorem, namely, that it holds by virtue of the structure of the natural numbers. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1) | |
| A reaction: This is because induction characterises the natural numbers, in the Peano Axioms. |
| 17942 | Can a proof that no one understands (of the four-colour theorem) really be a proof? [Colyvan] |
| Full Idea: The proof of the four-colour theorem raises questions about whether a 'proof' that no one understands is a proof. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 9.1.6) | |
| A reaction: The point is that the theorem (that you can colour countries on a map with just four colours) was proved with the help of a computer. |
| 17937 | Mathematical generalisation is by extending a system, or by abstracting away from it [Colyvan] |
| Full Idea: One type of generalisation in mathematics extends a system to go beyond what is was originally set up for; another kind involves abstracting away from some details in order to capture similarities between different systems. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.2) |
| 9249 | Whether we are free is uninteresting; we can only experience our freedom [Camus] |
| Full Idea: Knowing whether or not a man is free doesn't interest me. I can only experience my own freedom. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs free') | |
| A reaction: Camus has the right idea. Personally I think you could drop the word 'freedom', and just say that I am confronted by the need to make decisions. |
| 9253 | The human heart has a tiresome tendency to label as fate only what crushes it [Camus] |
| Full Idea: The human heart has a tiresome tendency to label as fate only what crushes it. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Appendix') | |
| A reaction: Nice. It might just as much be fate that you live a happy bourgeois life, as that you inadvertently murder your own father at a crossroads. But you can't avoid the powerful awareness of fate when a road accident occurs. |
| 9250 | Discussing ethics is pointless; moral people behave badly, and integrity doesn't need rules [Camus] |
| Full Idea: There can be no question of holding forth on ethics. I have seen people behave badly with great morality and I note every day that integrity has no need of rules. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs Man') | |
| A reaction: I don't agree. If someone 'behaves badly with great morality' there is something wrong with their morality, and I want to know what it is. The last part is more plausible, and could be a motto for Particularism. Rules dangerously over-simplify life. |
| 3053 | Pythagoras taught that virtue is harmony, and health, and universal good, and God [Pythagoras, by Diog. Laertius] |
| Full Idea: Pythagoras taught that virtue is harmony, and health, and universal good, and God. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 08.1.19 | |
| A reaction: I like the link with health, because I consider that a bridge over the supposed fact-value gap. Very Pythagorean to think that virtue is harmony. Plato liked that thought. |
| 9252 | The more one loves the stronger the absurd grows [Camus] |
| Full Idea: The more one loves the stronger the absurd grows. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Don Juan') | |
| A reaction: A penetrating remark, to be placed as a contrary to the remarks of Harry Frankfurt on love. But if the absurd increases the intensity of life, as Camus thinks, then they both make love the great life-affirmation, but in different ways. |
| 9251 | One can be virtuous through a whim [Camus] |
| Full Idea: One can be virtuous through a whim. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs Man') | |
| A reaction: A nice remark. Obviously neither Aristotle nor Kant would be too impressed by someone who did this, and Aristotle would certainly say that it is not really virtue, but merely right behaviour. I agree with Aristotle. |
| 5244 | For Pythagoreans, justice is simply treating all people the same [Pythagoras, by Aristotle] |
| Full Idea: Some even think that what is just is simple reciprocity, as the Pythagoreans maintained, because they defined justice simply as having done to one what one has done to another. | |
| From: report of Pythagoras (reports [c.530 BCE], 28) by Aristotle - Nicomachean Ethics 1132b22 | |
| A reaction: One wonders what Pythagoreans made of slavery. Aristotle argues that officials, for example, have superior rights. The Pythagorean idea makes fairness the central aspect of justice, and that must at least be partly right. |
| 9243 | If we believe existence is absurd, this should dictate our conduct [Camus] |
| Full Idea: What a man believes to be true must determine his action. Belief in the absurdity of existence must then dictate his conduct. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs and Suic') | |
| A reaction: It is intriguing to speculate what the appropriate conduct is. Presumably it is wild existential gestures, like sticking a knife through your hand. Suicide will be an obvious temptation. But bourgeois life might be equally appropriate. |
| 6708 | Happiness and the absurd go together, each leading to the other [Camus] |
| Full Idea: Happiness and the absurd are two sons of the same earth; they are inseparable; it would be a mistake to say that happiness necessarily springs from the absurd discovery; it happens as well that the feeling of the absurd springs from happiness. | |
| From: Albert Camus (The Myth of Sisyphus [1942], p.110) | |
| A reaction: I'm not sure that I understand this, but I understand the experience of absurdity, and I can see that somehow one feels a bit more alive when one acknowledges the absurdity of it all. Meta-meta-thought is the highest form of human life, I say. |
| 9242 | Essential problems either risk death, or intensify the passion of life [Camus] |
| Full Idea: The essential problems are those that run the risk of leading to death, or those that intensify the passion of living. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs and Suic') | |
| A reaction: This seems to be distinctively existentialist, in a way that a cool concern for great truths are not ranked as so important. Ranking dangerous problems as crucial seems somehow trivial for a philosopher. Intensity of life is more impressive. |
| 9246 | Danger and integrity are not in the leap of faith, but in remaining poised just before the leap [Camus] |
| Full Idea: The leap of faith does not represent an extreme danger as Kierkegaard would like it to do. The danger, on the contrary, lies in the subtle instant that precedes the leap. Being able to remain on the dizzying crest - that is integrity. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Phil Suic') | |
| A reaction: I have always found that a thrilling thought. It perfectly distinguishes atheist existentialism from religious existentialism. It is Camus' best image for how the Absurd can be a life affirming idea, rather than a sort of nihilism. Life gains intensity. |
| 9248 | It is essential to die unreconciled and not of one's own free will [Camus] |
| Full Idea: It is essential to die unreconciled and not of one's own free will. Suicide is a repudiation. | |
| From: Albert Camus (The Myth of Sisyphus [1942], 'Abs free') | |
| A reaction: Camus' whole book addresses the question of suicide. He suggests that life can be redeemed and become livable if you squarely face up to the absurdity of it, and the gap between what we hope for and what we get. |
| 638 | Pythagoreans define timeliness, justice and marriage in terms of numbers [Pythagoras, by Aristotle] |
| Full Idea: The Pythagoreans offered definitions of a limited range of things on the basis of numbers; examples are timeliness, justice and marriage. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Aristotle - Metaphysics 1078b |
| 553 | Pythagoreans think mathematical principles are the principles of all of nature [Pythagoras, by Aristotle] |
| Full Idea: The Pythagoreans thought that the principles of mathematical entities were the principles of all entities. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Aristotle - Metaphysics 985b |
| 375 | When musical harmony and rhythm were discovered, similar features were seen in bodily movement [Pythagoras, by Plato] |
| Full Idea: When our predecessors discovered musical scales, they also discovered similar features in bodily movement, which should also be measured numerically, and called 'tempos' and 'measures'. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Plato - Philebus 17d |
| 554 | Pythagoreans say things imitate numbers, but Plato says things participate in numbers [Pythagoras, by Aristotle] |
| Full Idea: Pythagoreans said that entities existed by imitation of the numbers, whereas Plato said that it was by participation. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Aristotle - Metaphysics 987b |
| 644 | For Pythagoreans the entire universe is made of numbers [Pythagoras, by Aristotle] |
| Full Idea: For Pythagoreans the entire universe is constructed of numbers. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Aristotle - Metaphysics 1080b |
| 7467 | The modern idea of an immortal soul was largely created by Pythagoras [Pythagoras, by Watson] |
| Full Idea: The modern concept of the immortal soul is a Greek idea, which owes much to Pythagoras. | |
| From: report of Pythagoras (reports [c.530 BCE]) by Peter Watson - Ideas Ch.5 | |
| A reaction: You can see why it caught on - it is a very appealing idea. Watson connects the 'modern' view with the ideas of heaven and hell. Obviously the idea of an afterlife goes a long way back (judging from the contents of ancient graves). |