19 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. |
| 8228 | Being is revealed at the point between waking and sleep [Anon (Cent)] |
| Full Idea: At the point of sleep when sleep has not yet come and external wakefulness vanishes, at this point being is revealed. | |
| From: Anon (Cent) (Centring [c.500 BCE], 50) | |
| A reaction: One for Heidegger. The problem with eastern philosophy is that no one expects that this revelation could be put into words, so we cannot compare our revelations of being, or pass them on to others. Which means they can't be criticised. |
| 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. |
| 8232 | Neglect your self, and feel the consciousness of each other being [Anon (Cent)] |
| Full Idea: Feel the consciousness of each person as your own consciousness. So, leaving aside concern for self, become each being. | |
| From: Anon (Cent) (Centring [c.500 BCE], 83) | |
| A reaction: Good. The western scepticism about other minds puts up a barrier to this sort of thought. The best of Zen is when it encourages the use of imagination to explore what is real. But imagination struggles to distinguish what is true. |
| 8230 | Just as you have the impulse to do something, stop [Anon (Cent)] |
| Full Idea: Just as you have the impulse to do something, stop. | |
| From: Anon (Cent) (Centring [c.500 BCE], 64) | |
| A reaction: Nice. You might train your own will like a dog in this way. It is a counterexample to the simplistic idea that all you need is a belief and a desire, and you have got an action. But (pace Searle, Ideas 3817 + 3818) this does not prove free will. |
| 1655 | If goodness needs true opinion but not knowledge, you can skip the 'examined life' [Vlastos on Plato] |
| Full Idea: If true opinion without knowledge does suffice to guide action aright, the great mass of men and women may be spared the pain and hazards of the "examined" life. | |
| From: comment on Plato (The Apology [c.383 BCE], 38a) by Gregory Vlastos - Socrates: Ironist and Moral Philosopher p.125 |
| 8234 | Bondage and liberation are relative terms, which only frighten those already terrified of the universe [Anon (Cent)] |
| Full Idea: Since in truth, bondage and freedom are relative, these words are only for those terrified with the universe. The universe is a reflection of minds. As you see many suns in water from one sun, so see bondage and liberation. | |
| From: Anon (Cent) (Centring [c.500 BCE], 110) | |
| A reaction: Since most easterners have experienced permanent social repression, their philosophies all encourage them not to worry about it. No wonder marxism, proved popular, when it suggested you could actually change things. |
| 8227 | Feel your whole body saturated with cosmic essence [Anon (Cent)] |
| Full Idea: Feel your substance, bones, flesh, blood, saturated with cosmic essence. | |
| From: Anon (Cent) (Centring [c.500 BCE], 23) | |
| A reaction: I find this unsatisfactory. Being a sad victim of materialistic western scientific culture, I don't think 'cosmic essence' exists. I could imagine myself full of the stuff, and that might feel good, but I could also imagine I had won the lottery. |
| 8231 | Abandon attachment to body, and feel the joy of being everywhere [Anon (Cent)] |
| Full Idea: Toss attachment for body aside, realising I am everywhere. One who is everywhere is joyous. | |
| From: Anon (Cent) (Centring [c.500 BCE], 79) | |
| A reaction: I really don't think it is wisdom to spend your time imagining things which are not true. I might imagine that some gorgeous film star is in love with me, but I don't recommend it. Live according to nature. We are physical beings. |
| 8229 | The serenity in blue sky beyond clouds [Anon (Cent)] |
| Full Idea: Simply by looking into blue sky beyond clouds - the serenity. | |
| From: Anon (Cent) (Centring [c.500 BCE], 59) | |
| A reaction: Philip Larkin finds the same experience looking through high windows. If we articulate the experience, it seems to combine humility and detachment. The sky makes us insignificant, but the mind can project into the sky. |
| 8233 | Imagine fire burning up your whole body, but not you [Anon (Cent)] |
| Full Idea: Focus on fire rising through your form from the toes up until the body burns to ashes, but not you. | |
| From: Anon (Cent) (Centring [c.500 BCE], 28) | |
| A reaction: Try very hard to persuade yourself that you are immortal, even if you are not. Hm. Zen Buddhism actually contains very little commitment to what is true or false. It explores interesting beliefs like children playing with toys. Very post-modern. |