42 ideas
| 7578 | I conceived it my task to create difficulties everywhere [Kierkegaard] |
| Full Idea: I conceived it my task to create difficulties everywhere. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Author') | |
| A reaction: Nice. It is like Socrates's image of himself as the 'gadfly' of Athens. The interesting question is always to see what the rest of society makes of having someone in their midst who sees it as their social role to 'create difficulties'. |
| 22047 | Wherever there is painless contradiction there is also comedy [Kierkegaard] |
| Full Idea: Wherever there is contradiction, the comical is also present. ...The tragic is the suffering contradiction, the comical is the painless contradiction. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], p.459), quoted by Terry Pinkard - German Philosophy 1760-1860 13 | |
| A reaction: He is not saying that this is the only source of comedy. I once heard an adult say that there is one thing that is always funny, and that is a fart. |
| 22092 | Kierkegaard's truth draws on authenticity, fidelity and honesty [Kierkegaard, by Carlisle] |
| Full Idea: Kierkegaard offers a different interpretation of truth, which draws on the notions of authenticity, fidelity and honesty. | |
| From: report of Søren Kierkegaard (Concluding Unscientific Postscript [1846]) by Clare Carlisle - Kierkegaard: a guide for the perplexed 4 | |
| A reaction: This notion of truth, meaning 'the real thing' (as in 'she was a true scholar'), seems to begin with Hegel. I suggest we use the word 'genuine' for that, and save 'truth' for its traditional role. It is disastrous to blur the simple concept of truth. |
| 15999 | Pure truth is for infinite beings only; I prefer endless striving for truth [Kierkegaard] |
| Full Idea: If God held all truth enclosed in his right hand, and in his left hand the ever-striving drive for truth, even if erring forever, and he were to say Choose! I would humbly fall at his left hand and say Father, give! Pure truth is for infinite beings only. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], p.106) | |
| A reaction: A sobering realistic thought of our own limitations; Kierkegaard allows that there is no limit to how far we can strive for truth. Just that truth is comprehended by infinite beings (if any), not by mere mortals. [SY] |
| 20313 | The highest truth we can get is uncertainty held fast by an inward passion [Kierkegaard] |
| Full Idea: An objective uncertainty held fast in an appropriation-process of the most passionate inwardness is the truth, the highest truth available for an existing individual. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846]) | |
| A reaction: [Bk 711] Offered as a definition of truth, knowing how strange and paradoxical it sounds. If we view all life as subjectivity, then there can of course be nothing more to truth than passionate conviction. Personally I think thought can be objective. |
| 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. |
| 17884 | Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner] |
| Full Idea: There are many coherent stopping points in the hierarchy of increasingly strong mathematical systems, starting with strict finitism, and moving up through predicativism to the higher reaches of set theory. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], Intro) |
| 17893 | 'Reflection principles' say the whole truth about sets can't be captured [Koellner] |
| Full Idea: Roughly speaking, 'reflection principles' assert that anything true in V [the set hierarchy] falls short of characterising V in that it is true within some earlier level. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 2.1) |
| 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'. |
| 17894 | We have no argument to show a statement is absolutely undecidable [Koellner] |
| Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3) |
| 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) |
| 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. |
| 17890 | There are at least eleven types of large cardinal, of increasing logical strength [Koellner] |
| Full Idea: Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable). | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) | |
| A reaction: [I don't understand how cardinals can have 'logical strength', but I pass it on anyway] |
| 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. |
| 17887 | PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner] |
| Full Idea: To the extent that we are justified in accepting Peano Arithmetic we are justified in accepting its consistency, and so we know how to expand the axiom system so as to overcome the limitation [of Gödel's Second Theorem]. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.1) | |
| A reaction: Each expansion brings a limitation, but then you can expand again. |
| 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) |
| 17891 | Arithmetical undecidability is always settled at the next stage up [Koellner] |
| Full Idea: The arithmetical instances of undecidability that arise at one stage of the hierarchy are settled at the next. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) |
| 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) |
| 20742 | The real subject is ethical, not cognitive [Kierkegaard] |
| Full Idea: The real subject is not the cognitive subject …the real subject is the ethically existing subject. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], p.281), quoted by Kevin Aho - Existentialism: an introduction 2 'Subjective' | |
| A reaction: Perhaps we should say the essence of the self is its drive to live, not its drive to know. Just getting through the day is top priority, and ethics don’t figure much for the solitary person. But each activity, such as cooking, has its virtues. |
| 7579 | While big metaphysics is complete without ethics, personal philosophy emphasises ethics [Kierkegaard] |
| Full Idea: While the Hegelian philosophy goes on and is finished without having an Ethics, the more simple philosophy which is propounded by an existing individual for existing individuals, will more especially emphasis the ethical. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Lessing') | |
| A reaction: This is reminiscent of the Socratic revolution, which shifted philosophy from the study of nature to the study of personal virtue. However, if we look for ethical teachings in existentialism, there often seems to be a black hole in the middle. |
| 7581 | Speculative philosophy loses the individual in a vast vision of humanity [Kierkegaard] |
| Full Idea: Being an individual man is a thing that has been abolished, and every speculative philosopher confuses himself with humanity at large, whereby he becomes infinitely great - and at the same time nothing at all. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Lessing') | |
| A reaction: Compare Idea 4840. This is a beautiful statement of the motivation for existentialism. The sort of philosophers who love mathematics (Plato, Descartes, Leibniz, Russell) love losing themselves in abstractions. This is the rebellion. |
| 20314 | People want to lose themselves in movements and history, instead of being individuals [Kierkegaard] |
| Full Idea: Everything must attach itself so as to be part of some movement; men are determined to lose themselves in the totality of things, in world-history, fascinated and deceived by a magic witchery; no one wants to be an individual human being. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846]) | |
| A reaction: [Bk 711] I presume 'world-history' refers to the exhilerating ideas of Hegel. Right now [2017] I would say we have far too much of people only wanting to be individuals, with insufficient attention to our social nature. |
| 7582 | Becoming what one is is a huge difficulty, because we strongly aspire to be something else [Kierkegaard] |
| Full Idea: Striving to become what one already is is a very difficult task, the most difficult of all, because every human being has a strong natural bent and passion to become something more and different. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Subjective') | |
| A reaction: Presumably most people continually drift between vanity and low self-esteem, and between unattainable daydreams and powerless immediate reality. That creates the stage on which Kierkegaard's interesting battle would have to be fought. |
| 7586 | God does not think or exist; God creates, and is eternal [Kierkegaard] |
| Full Idea: God does not think, He creates; God does not exist, he is eternal. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Thinker') | |
| A reaction: The sort of nicely challenging remarks we pay philosophers to come up with. I don't understand the second claim, but the first one certainly avoids all paradoxes that arise if God experiences all the intrinsic problems of thinking. |
| 20312 | God cannot be demonstrated objectively, because God is a subject, only existing inwardly [Kierkegaard] |
| Full Idea: Choosing the objective way enters upon the entire approximation-process by which it is proposed to bring God to light objectively. But this is in all eternity impossible, because God is a subject, and therefore exist only for subjectivity in inwardness. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846]) | |
| A reaction: [pg in 711] This seems to have something like Wittgenstein's problem with a private language - that with no external peer-review it is unclear what the commitment is. |
| 7580 | Pantheism destroys the distinction between good and evil [Kierkegaard] |
| Full Idea: So called pantheistic systems have often been characterised and challenged by the assertion that they abrogate the distinction between good and evil. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Lessing') | |
| A reaction: He will have Spinoza in mind. Interesting. Obviously this criticism would come from someone who thought that the traditional deity was the only source of goodness. Good/evil isn't all-or-nothing. A monistic system could contain them. |
| 7583 | Faith is the highest passion in the sphere of human subjectivity [Kierkegaard] |
| Full Idea: Faith is the highest passion in the sphere of human subjectivity. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Subjective') | |
| A reaction: The word 'highest' should always ring alarm bells. The worst sort of religious fanatics seem to be in the grip of this 'high' passion. The early twenty-first century is an echo of eighteenth century England, with its dislike of religious 'enthusiasm'. |
| 7584 | Without risk there is no faith [Kierkegaard] |
| Full Idea: Without risk there is no faith. | |
| From: Søren Kierkegaard (Concluding Unscientific Postscript [1846], 'Inwardness') | |
| A reaction: Remarks like this make you realise that Kierkegaard is just as much of a romantic as most of the other nineteenth century philosophers. Plunge into the dark unknown of the human psyche, in order to intensify and heighten human life. |