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. |
| 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. |
| 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. |
| 6866 | It is disturbing if we become unreal when we die, but if time is unreal, then we remain real after death [Le Poidevin] |
| Full Idea: For the A-theorists called 'presentists' the past is as unreal as the future, and reality leaves us behind once we die, which is disturbing; but B-theorists, who see time as unreal, say we are just as real after our deaths as we were beforehand. | |
| From: Robin Le Poidevin (Interview with Baggini and Stangroom [2001], p.174) | |
| A reaction: See Idea 6865 for A and B theories. I wonder if this problem is only superficially 'disturbing'. Becoming unreal may sound more drastic than becoming dead, but they both sound pretty terminal to me. |
| 6867 | Existentialism focuses on freedom and self-making, and insertion into the world [Le Poidevin] |
| Full Idea: I take existentialism to be the focus on the freedom and self-making of the human being, and his or her insertion into the world. | |
| From: Robin Le Poidevin (Interview with Baggini and Stangroom [2001], p.222) | |
| A reaction: I take 'self-making' to be the key here. If neuroscientists somehow 'proved' that there was no free will, I don't see that making any difference to existentialism. 'Insertion' seems odd, unless it refers to growing up. |
| 23831 | The essence of power is illusory prestige [Weil] |
| Full Idea: Prestige, which is an illusion, is the very essence of power. | |
| From: Simone Weil (The Power of Words [1934], p.255) | |
| A reaction: It is hard to maintain illusory prestige if there is no actual power behind it. |
| 23830 | A group is only dangerous if it endorses an abstract entity [Weil] |
| Full Idea: Any group which has not secreted an abstract entity will probably not be dangerous. | |
| From: Simone Weil (The Power of Words [1934], p.255) | |
| A reaction: Written in the 1930s, the era of many political -isms. No group can be united if it lacks a clear label, and a few simple slogans. |
| 23829 | National leaders want to preserve necessary order - but always the existing order [Weil] |
| Full Idea: Those in command see their duty as defending order, without which no social life can survive; and the only order they conceive is the existing one. | |
| From: Simone Weil (The Power of Words [1934], p.249) | |
| A reaction: She sympathises with them, because a new order is such an unknown. But it always struck me as weird that traditions are preserved because they are traditions, and not because they are good. (My old school, for example!). |
| 23828 | National prestige consists of behaving as if you could beat the others in a war [Weil] |
| Full Idea: What is called national prestige consists in behaving always in such a way as to demoralise other nations by giving them the impression that, if it comes to war, one would certainly defeat them. | |
| From: Simone Weil (The Power of Words [1934], p.244) | |
| A reaction: It's true. No nation gains prestige because of the happy lives of its citizens, or the creativity of its culture. |
| 23827 | Modern wars are fought in the name of empty words which are given capital letters [Weil] |
| Full Idea: For our contemporaries the role of Helen in the Trojan War is is played by words with capital letters. …When empty words are given capital letters, then, on the slightest pretext, men will begin shedding blood for them and piling up ruin in their name. | |
| From: Simone Weil (The Power of Words [1934], p.241) | |
| A reaction: This seems particularly true of the 1930s, where specific dogmatic ideologies seemed to grip and divide people. Simple aggressive nationalism seems to be the cause of current wars, now the fear of Communism has diminished. |
| 6865 | A-theory says past, present, future and flow exist; B-theory says this just reports our perspective [Le Poidevin] |
| Full Idea: The A-theory regards our intuitive distinction of time into past, present and future as objective, and takes seriously the idea that time flows; the B-theory says this just reflects our perspective, like the spatial distinction between here and there. | |
| From: Robin Le Poidevin (Interview with Baggini and Stangroom [2001], p.174) | |
| A reaction: The distinction comes from McTaggart. Physics seems to be built on an objective view of time, and yet Einstein makes time relative. What possible evidence could decide between the two theories? |