18 ideas
| 8952 | We reach 'reflective equilibrium' when intuitions and theory completely align [Fisher] |
| Full Idea: A state of 'reflective equilibrium' is when our theory and our intuitions become completely aligned | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 12.IV) | |
| A reaction: [Rawls made this concept famous] This is a helpful concept in trying to spell out the ideal which is the dream of believers in 'pure reason' - that there is a goal in which everything comes right. The problem is when people have different intuitions! |
| 8943 | Three-valued logic says excluded middle and non-contradition are not tautologies [Fisher] |
| Full Idea: In three-valued logic (L3), neither the law of excluded middle (p or not-p), nor the law of non-contradiction (not(p and not-p)) will be tautologies. If p has the value 'indeterminate' then so will not-p. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 07.I) | |
| A reaction: I quite accept that the world is full of indeterminate propositions, and that excluded middle and non-contradiction can sometimes be uncertain, but I am reluctant to accept that what is being offered here should be called 'logic'. |
| 8945 | Fuzzy logic has many truth values, ranging in fractions from 0 to 1 [Fisher] |
| Full Idea: In fuzzy logic objects have properties to a greater or lesser degree, and truth values are given as fractions or decimals, ranging from 0 to 1. Not-p is defined as 1-p, and other formula are defined in terms of maxima and minima for sets. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 07.II) | |
| A reaction: The question seems to be whether this is actually logic, or a recasting of probability theory. Susan Haack attacks it. If logic is the study of how truth is preserved as we move between propositions, then 0 and 1 need a special status. |
| 8951 | Classical logic is: excluded middle, non-contradiction, contradictions imply all, disjunctive syllogism [Fisher] |
| Full Idea: For simplicity, we can say that 'classical logic' amounts to the truth of four sentences: 1) either p or not-p; 2) it is not the case that both p and not-p; 3) from p and not-p, infer q; 4) from p or q and not-p, infer q. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 12.I) | |
| A reaction: [She says there are many ways of specifying classical logic] Intuition suggests that 2 and 4 are rather hard to dispute, while 1 is ignoring some grey areas, and 3 is totally ridiculous. There is, of course, plenty of support for 3! |
| 8950 | Logic formalizes how we should reason, but it shouldn't determine whether we are realists [Fisher] |
| Full Idea: Even if one is inclined to be a realist about everything, it is hard to see why our logic should be the determiner. Logic is supposed to formalize how we ought to reason, but whether or not we should be realists is a matter of philosophy, not logic. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 09.I) | |
| A reaction: Nice to hear a logician saying this. I do not see why talk in terms of an object is a commitment to its existence. We can discuss the philosopher's stone, or Arthur's sword, or the Loch Ness monster, or gravitinos, with degrees of commitment. |
| 14620 | Theories in logic are sentences closed under consequence, but in truth discussions theories have axioms [Fine,K] |
| Full Idea: It is customary in logic to take a theory to be a set of sentences closed under logical consequence, whereas it is common in discussions of theories of truth to take a theory to be an axiomatized theory. | |
| From: Kit Fine (Semantic Necessity [2010], n8) |
| 8946 | We could make our intuitions about heaps precise with a million-valued logic [Fisher] |
| Full Idea: We could construct a 1,000,000-valued logic that would allow our intuitions concerning a heap to vary exactly with the amount of sand in the heap. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008]) | |
| A reaction: Presumably only an infinite number of grains of sand would then produce a true heap, and even one grain would count as a bit of a heap, which must both be wrong, so I can't see this helping much. |
| 8944 | Vagueness can involve components (like baldness), or not (like boredom) [Fisher] |
| Full Idea: Vague terms come in at least two different kinds: those whose constituent parts come in discrete packets (bald, rich, red) and those that don't (beauty, boredom, niceness). | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 07.II) | |
| A reaction: The first group seem to be features of the external world, and the second all occur in the mind. Baldness may be vague, but presumably hairs are (on the whole) not. Nature doesn't care whether someone is actually 'bald' or not. |
| 8941 | We can't explain 'possibility' in terms of 'possible' worlds [Fisher] |
| Full Idea: Explaining 'it is possible that p' by saying p is true in at least one possible world doesn't get me very far. If I don't understand what possibility is, then appealing to possible worlds is not going to do me much good. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 06.III) | |
| A reaction: This seems so blatant that I assume friends of possible worlds will have addressed the problem. Note that you will also need to understand 'possible' to define necessity as 'true in all possible worlds'. Necessarily-p is not-possibly-not-p. |
| 23900 | Chance is compatible with necessity, and the two occur together [Weil] |
| Full Idea: Chance is not the contrary of necessity; it is not incompatible with necessity. On the contrary, it never appears except at the same time as necessity. | |
| From: Simone Weil (The Scientific Image [1941], p.175) | |
| A reaction: She illustrates it with the six terminating results of a die throw, and the innumerabe ways the throw can occur. This thought strikes me as relevant to discussions of free will. …But I'm not sure I fully understand it. |
| 8947 | If all truths are implied by a falsehood, then not-p might imply both q and not-q [Fisher] |
| Full Idea: If all truths are implied by a falsehood, then 'if there are no trees in the park then there is no shade' and 'if there are no trees in the park there is plenty of shade' both come out as true. Intuitively, though, the second one is false. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 08.I) | |
| A reaction: The rule that a falsehood implies all truths must be the weakest idea in classical logic, if it actually implies a contradiction. This means we must take an interest in relevance logics. |
| 8949 | In relevance logic, conditionals help information to flow from antecedent to consequent [Fisher] |
| Full Idea: A good account of relevance logic suggests that a conditional will be true when the flow of information is such that a conditional is the device that helps information to flow from the antecedent to the consequent. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 08.III) | |
| A reaction: Hm. 'If you are going out, you'll need an umbrella'. This passes on information about 'out', but also brings in new information. 'If you are going out, I'm leaving you'. What flows is an interpretation of the antecedent. Tricky. |
| 14530 | The role of semantic necessity in semantics is like metaphysical necessity in metaphysics [Fine,K, by Hale/Hoffmann,A] |
| Full Idea: Fine's paper argues that the notion of semantic necessity has a role to play in understanding the nature and content of semantics comparable to the role of metaphysical necessity in metaphysics. | |
| From: report of Kit Fine (Semantic Necessity [2010]) by Bob Hale/ Aviv Hoffmann - Introduction to 'Modality' 2 |
| 14618 | Semantics is either an assignment of semantic values, or a theory of truth [Fine,K] |
| Full Idea: On one view, a semantics for a given language is taken to be an assignment of semantic values to its expressions; according to the other, a semantics is taken to be a theory of truth for that language. | |
| From: Kit Fine (Semantic Necessity [2010], Intro) | |
| A reaction: The first is Frege, the second Tarski via Davidson, says Fine. Fine argues against these as the correct alternatives, and says the distinction prevents us understanding what is really going on. He votes for semantics as giving 'semantic requirements'. |
| 14621 | Semantics is a body of semantic requirements, not semantic truths or assigned values [Fine,K] |
| Full Idea: Semantics should be conceived as a body of semantic requirements or facts - and not as a body of semantic truths, or as an assignment of semantic values. | |
| From: Kit Fine (Semantic Necessity [2010], 5) | |
| A reaction: The 'truths' view is Tarski, and the 'values' view is Frege. You'll have to read the Fine paper to grasp his subtle claim. |
| 14622 | Referential semantics (unlike Fregeanism) allows objects themselves in to semantic requirements [Fine,K] |
| Full Idea: What distinguishes the referential position in semantics from Fregeanism is that it makes use of de re semantic facts, in which it is required of an object itself that it enter into certain semantic requirements. | |
| From: Kit Fine (Semantic Necessity [2010], 5) | |
| A reaction: I have a repugnance to any sort of semantics that involves the objects themselves, even when dealing with proper names. If I talk of 'Napoleon', no small Frenchman is to be found anywhere in my sentences. |
| 14619 | The Quinean doubt: are semantics and facts separate, and do analytic sentences have no factual part? [Fine,K] |
| Full Idea: The source of the Quinean scepticism about analytic and synthetic is, first, scepticism over whether we can factor truth into a semantic and a factual component, and (second) if we can, is the factual component ever null? | |
| From: Kit Fine (Semantic Necessity [2010], 1) | |
| A reaction: You certainly can't grasp 'bachelors are unmarried men' if you haven't grasped the full Woosterian truth about men and marriage. But I could interdefine four meaningless words, so that you could employ them in analytic sentences. |
| 23899 | The secret of art is that beauty is a just blend of unity and its opposite [Weil] |
| Full Idea: A just blend of unity and that which opposes it is the condition of the beautiful, and it is the secret of art. | |
| From: Simone Weil (The Scientific Image [1941], p.169) | |
| A reaction: Rather sweeping, but the observation strikes me as fairly accurate. It seems to work for most novels, paintings and music, though more recent art may provide counterexamples. |