44 ideas
| 15053 | If metaphysics can't be settled, it hardly matters whether it makes sense [Fine,K] |
| Full Idea: If there is no way of settling metaphysical questions, then who cares whether or not they make sense? | |
| From: Kit Fine (The Question of Realism [2001], 4 n20) | |
| A reaction: This footnote is aimed at logical positivists, who seemed to worry about whether metaphysics made sense, and also dismissed its prospects even if it did make sense. |
| 15054 | 'Quietist' says abandon metaphysics because answers are unattainable (as in Kant's noumenon) [Fine,K] |
| Full Idea: The 'quietist' view of metaphysics says that realist metaphysics should be abandoned, not because its questions cannot be framed, but because their answers cannot be found. The real world of metaphysics is akin to Kant's noumenal world. | |
| From: Kit Fine (The Question of Realism [2001], 4) | |
| A reaction: [He cites Blackburn, Dworkin, A.Fine, and Putnam-1987 as quietists] Fine aims to clarify the concepts of factuality and of ground, in order to show that metaphysics is possible. |
| 6950 | You can be rational with undetected or minor inconsistencies [Harman] |
| Full Idea: Rationality doesn't require consistency, because you can be rational despite undetected inconsistencies in beliefs, and it isn't always rational to respond to a discovery of inconsistency by dropping everything in favour of eliminating that inconsistency. | |
| From: Gilbert Harman (Rationality [1995], 1.2) | |
| A reaction: This strikes me as being correct, and is (I am beginning to realise) a vital contribution made to our understanding by pragmatism. European thinking has been too keen on logic as the model of good reasoning. |
| 6954 | A coherent conceptual scheme contains best explanations of most of your beliefs [Harman] |
| Full Idea: A set of unrelated beliefs seems less coherent than a tightly organized conceptual scheme that contains explanatory principles that make sense of most of your beliefs; this is why inference to the best explanation is an attractive pattern of inference. | |
| From: Gilbert Harman (Rationality [1995], 1.5.2) | |
| A reaction: I find this a very appealing proposal. The central aim of rational thought seems to me to be best explanation, and I increasingly think that most of my beliefs rest on their apparent coherence, rather than their foundations. |
| 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. |
| 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) |
| 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. |
| 15007 | If you make 'grounding' fundamental, you have to mention some non-fundamental notions [Sider on Fine,K] |
| Full Idea: My main objection to Fine's notion of grounding as fundamental is that it violates 'purity' - that fundamental truths should involve only fundamental notions. | |
| From: comment on Kit Fine (The Question of Realism [2001]) by Theodore Sider - Writing the Book of the World 08.2 | |
| A reaction: [p.106 of Sider for 'purity'] The point here is that to define a grounding relation you have to mention the 'higher' levels of the relationship (as in a 'city' being grounded in physical stuff), which doesn't seem fundamental enough. |
| 15006 | Something is grounded when it holds, and is explained, and necessitated by something else [Fine,K, by Sider] |
| Full Idea: When p 'grounds' q then q holds in virtue of p's holding; q's holding is nothing beyond p's holding; the truth of p explains the truth of q in a particularly tight sense (explanation of q by p in this sense requires that p necessitates q). | |
| From: report of Kit Fine (The Question of Realism [2001], 15-16) by Theodore Sider - Writing the Book of the World 08.1 | |
| A reaction: This proposal has become a hot topic in current metaphysics, as attempts are made to employ 'grounding' in various logical, epistemological and ontological contexts. I'm a fan - it is at the heart of metaphysics as structure of reality. |
| 15055 | Grounding relations are best expressed as relations between sentences [Fine,K] |
| Full Idea: I recommend that a statement of ground be cast in the following 'canonical' form: Its being the case that S consists in nothing more than its being the case that T, U... (where S, T, U... are particular sentences). | |
| From: Kit Fine (The Question of Realism [2001], 5) | |
| A reaction: The point here is that grounding is to be undestood in terms of sentences (and 'its being the case that...'), rather than in terms of objects, properties or relations. Fine thus makes grounding a human activity, rather than a natural activity. |
| 15050 | Reduction might be producing a sentence which gets closer to the logical form [Fine,K] |
| Full Idea: One line of reduction is logical analysis. To say one sentence reduces to another is to say that they express the same proposition (or fact), but the grammatical form of the second is closer to the logical form than the grammatical form of the first. | |
| From: Kit Fine (The Question of Realism [2001], 3) | |
| A reaction: Fine objects that S-and-T reduces to S and T, which is two propositions. He also objects that this approach misses the de re ingredient in reduction (that it is about the things themselves, not the sentences). It also overemphasises logical form. |
| 15051 | Reduction might be semantic, where a reduced sentence is understood through its reduction [Fine,K] |
| Full Idea: A second line of reduction is semantic, and holds in virtue of the meaning of the sentences. It should then be possible to acquire an understanding of the reduced sentence on the basis of understanding the sentences to which it reduces. | |
| From: Kit Fine (The Question of Realism [2001], 3) | |
| A reaction: Fine says this avoids the first objection to the grammatical approach (see Reaction to Idea 15050), but still can't handle the de re aspect of reduction. Fine also doubts whether this understanding qualifies as 'reduction'. |
| 15052 | Reduction is modal, if the reductions necessarily entail the truth of the target sentence [Fine,K] |
| Full Idea: The third, more recent, approach to reduction is a modal matter. A class of propositions will reduce to - or supervene upon - another if, necessarily, any truth from the one is entailed by truths from the other. | |
| From: Kit Fine (The Question of Realism [2001], 3) | |
| A reaction: [He cites Armstrong, Chalmers and Jackson for this approach] Fine notes that some people reject supervenience as a sort of reduction. He objects that this reduction doesn't necessarily lead to something more basic. |
| 15056 | The notion of reduction (unlike that of 'ground') implies the unreality of what is reduced [Fine,K] |
| Full Idea: The notion of ground should be distinguished from the strict notion of reduction. A statement of reduction implies the unreality of what is reduced, but a statement of ground does not. | |
| From: Kit Fine (The Question of Realism [2001], 5) | |
| A reaction: That seems like a bit of a caricature of reduction. If you see a grey cloud and it reduces to a swarm of mosquitoes, you do not say that the cloud was 'unreal'. Fine is setting up a stall for 'ground' in the metaphysical market. We all seek structure. |
| 15047 | What is real can only be settled in terms of 'ground' [Fine,K] |
| Full Idea: Questions of what is real are to be settled upon the basis of considerations of ground. | |
| From: Kit Fine (The Question of Realism [2001], Intro) | |
| A reaction: This looks like being one of Fine's most important ideas, which is shifting the whole basis of contemporary metaphysics. Only Parmenides and Heidegger thought Being was the target. Aristotle aims at identity. What grounds what is a third alternative. |
| 15046 | Reality is a primitive metaphysical concept, which cannot be understood in other terms [Fine,K] |
| Full Idea: I conclude that there is a primitive metaphysical concept of reality, one that cannot be understood in fundamentally different terms. | |
| From: Kit Fine (The Question of Realism [2001], Intro) | |
| A reaction: Fine offers arguments to support his claim, but it seems hard to disagree with. The only alternative I can see is to understand reality in terms of our experiences, and this is the road to metaphysical hell. |
| 15060 | Why should what is explanatorily basic be therefore more real? [Fine,K] |
| Full Idea: We may grant that some things are explanatorily more basic than others, but why should that make them more real? | |
| From: Kit Fine (The Question of Realism [2001], 8) | |
| A reaction: This is the question asked by the 'quietist'. Fine's answer is that our whole conception of Reality, with its intrinsic structure, is what lies at the basis, and this is primitive. |
| 15048 | In metaphysics, reality is regarded as either 'factual', or as 'fundamental' [Fine,K] |
| Full Idea: The first main approach says metaphysical reality is to be identified with what is 'objective' or 'factual'. ...According to the second conception, metaphysical reality is to be identified with what is 'irreducible' or 'fundamental'. | |
| From: Kit Fine (The Question of Realism [2001], 1) | |
| A reaction: Fine is defending the 'fundamental' approach, via the 'grounding' relation. The whole structure, though, seems to be reality. In particular, a complete story must include the relations which facilitate more than mere fundamentals. |
| 15061 | Although colour depends on us, we can describe the world that way if it picks out fundamentals [Fine,K] |
| Full Idea: As long as colour terms pick out fundamental physical properties, I would be willing to countenance their use in the description of Reality in itself, ..even if they are based on a peculiar form of sensory awareness. | |
| From: Kit Fine (The Question of Realism [2001], 8) | |
| A reaction: This seems to explain why metaphysicians are so fond of using colour as their example of a property, when it seems rather subjective. There seem to be good reasons for rejecting Fine's view. |
| 6955 | Enumerative induction is inference to the best explanation [Harman] |
| Full Idea: We might think of enumerative induction as inference to the best explanation, taking the generalization to explain its instances. | |
| From: Gilbert Harman (Rationality [1995], 1.5.2) | |
| A reaction: This is a helpful connection. The best explanation of these swans being white is that all swans are white; it ceased to be the best explanation when black swans turned up. In the ultimate case, a law of nature is the explanation. |
| 6952 | Induction is 'defeasible', since additional information can invalidate it [Harman] |
| Full Idea: It is sometimes said that inductive reasoning is 'defeasible', meaning that considerations that support a given conclusion can be defeated by additional information. | |
| From: Gilbert Harman (Rationality [1995], 1.4.5) | |
| A reaction: True. The point is that being defeasible does not prevent such thinking from being rational. The rational part of it is to acknowledge that your conclusion is defeasible. |
| 6953 | All reasoning is inductive, and deduction only concerns implication [Harman] |
| Full Idea: Deductive logic is concerned with deductive implication, not deductive reasoning; all reasoning is inductive | |
| From: Gilbert Harman (Rationality [1995], 1.4.5) | |
| A reaction: This may be an attempt to stipulate how the word 'reasoning' should be used in future. It is, though, a bold and interesting claim, given the reputation of induction (since Hume) of being a totally irrational process. |
| 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) |
| 15059 | Grounding is an explanation of truth, and needs all the virtues of good explanations [Fine,K] |
| Full Idea: The main sources of evidence for judgments of ground are intuitive and explanatory. The relationship of ground is a form of explanation, ..explaining what makes a proposition true, which needs simplicity, breadth, coherence, non-circularity and strength. | |
| From: Kit Fine (The Question of Realism [2001], 7) | |
| A reaction: My thought is that not only must grounding explain, and therefore be a good explanation, but that the needs of explanation drive our decisions about what are the grounds. It is a bit indeterminate which is tail and which is dog. |
| 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. |
| 15057 | Ultimate explanations are in 'grounds', which account for other truths, which hold in virtue of the grounding [Fine,K] |
| Full Idea: We take ground to be an explanatory relation: if the truth that P is grounded in other truths, then they account for its truth; P's being the case holds in virtue of the other truths' being the case. ...It is the ultimate form of explanation. | |
| From: Kit Fine (The Question of Realism [2001], 5) | |
| A reaction: To be 'ultimate' that which grounds would have to be something which thwarted all further explanation. Popper, for example, got quite angry at the suggestion that we should put a block on further investigation in this way. |
| 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) |
| 6951 | Ordinary rationality is conservative, starting from where your beliefs currently are [Harman] |
| Full Idea: Ordinary rationality is generally conservative, in the sense that you start from where you are, with your present beliefs and intentions. | |
| From: Gilbert Harman (Rationality [1995], 1.3) | |
| A reaction: This stands opposed to the Cartesian or philosophers' rationality, which requires that (where possible) everything be proved from scratch. Harman seems right, that the normal onus of proof is on changing beliefs, rather proving you should retain them. |
| 15058 | A proposition ingredient is 'essential' if changing it would change the truth-value [Fine,K] |
| Full Idea: A proposition essentially contains a given constituent if its replacement by some other constituent induces a shift in truth value. Thus Socrates is essential to the proposition that Socrates is a philosopher, but not to Socrates is self-identical. | |
| From: Kit Fine (The Question of Realism [2001], 6) | |
| A reaction: In this view the replacement of 'is' by 'isn't' would make 'is' (or affirmation) part of the essence of most propositions. This is about linguistic essence, rather than real essence. It has the potential to be trivial. Replace 'slightly' by 'fairly'? |