25 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! |
| 8893 | For any given area, there seem to be a huge number of possible coherent systems of beliefs [Bonjour] |
| Full Idea: The 2nd standard objection to coherence is 'alternative coherent systems' - that there will be indefinitely many possible systems of belief in relation to any given subject area, each as internally coherent as the others. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 3.2) | |
| A reaction: This seems to imply that you could just invent an explanation, as long as it was coherent, but presumably good coherence is highly sensitive to the actual evidence. Bonjour observes that many of these systems would not survive over time. |
| 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. |
| 11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
| Full Idea: If a designated conclusion follows from the premisses, but the argument involves two howlers which cancel each other out, then the moral is that the path an argument takes from premisses to conclusion does matter to its logical evaluation. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], II) | |
| A reaction: The drift of this is that our view of logic should be a little closer to the reasoning of ordinary language, and we should rely a little less on purely formal accounts. |
| 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. |
| 11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
| Full Idea: A connective will possess the sense that it has by virtue of its competent users' finding certain rules of inference involving it to be primitively obvious. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], III) | |
| A reaction: Rumfitt cites Peacocke as endorsing this view, which characterises the logical connectives by their rules of usage rather than by their pure semantic value. |
| 11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
| Full Idea: If 'and' and 'but' really are alike in sense, in what might that likeness consist? Some philosophers of classical logic will reply that they share a sense by virtue of sharing a truth table. | |
| From: Ian Rumfitt ("Yes" and "No" [2000]) | |
| A reaction: This is the standard view which Rumfitt sets out to challenge. |
| 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. |
| 8888 | The concept of knowledge is so confused that it is best avoided [Bonjour] |
| Full Idea: The concept of knowledge is seriously problematic in more than one way, and is best avoided as far as possible in sober epistemological discussion. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 1.5) | |
| A reaction: Two sorts of states seem to be conflated: one where an animal has a true belief caused by an environmental event, and the other where a scholar pores over books and experiments to arrive at a hard-won truth. I say only the second is 'knowledge'. |
| 8887 | It is hard to give the concept of 'self-evident' a clear and defensible characterization [Bonjour] |
| Full Idea: Foundationalists find it difficult to attach a clear and defensible content to the idea that basic beliefs that are characterized as 'self-justified' or 'self-evident'. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 1.4) | |
| A reaction: A little surprising from a fan of a priori foundations, especially given that 'self-evident' is common usage, and not just philosophers' jargon. I think we can talk of self-evidence without a precise definition. We talk of an 'ocean' without trouble. |
| 8897 | The adverbial account will still be needed when a mind apprehends its sense-data [Bonjour] |
| Full Idea: The adverbial account of the content of experience is almost certainly correct, because no account can be given of the relation between sense-data and the apprehending mind that is independent of the adverbial theory. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 5.1 n3) | |
| A reaction: This boils down to the usual objection to sense-data, which is 'cut out the middle man'. Bonjour is right that at some point the mind has finally to experience whatever is coming in, and it must experience it in a particular way. |
| 8896 | Conscious states have built-in awareness of content, so we know if a conceptual description of it is correct [Bonjour] |
| Full Idea: If we describe a non-conceptual conscious state, we are aware of its character via the constitutive or 'built-in' awareness of content without need for a conceptual description, and so recognise that a conceptually formulated belief about it is correct. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 4.3) | |
| A reaction: This is Bonjour working very hard to find an account of primitive sense experiences which will enable them to function as 'basic beliefs' for foundations, without being too thin to do anything, or too thick to be basic. I'm not convinced. |
| 8891 | My incoherent beliefs about art should not undermine my very coherent beliefs about physics [Bonjour] |
| Full Idea: If coherentism is construed as involving the believer's entire body of beliefs, that would imply, most implausibly, that the justification of a belief in one area (physics) could be undermined by serious incoherence in another area (art history). | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 3.1) | |
| A reaction: Bonjour suggests that a moderated coherentism is needed to avoid this rather serious problem. It is hard to see how a precise specification could be given of 'areas' and 'local coherence'. An idiot about art would inspire little confidence on physics. |
| 8892 | Coherence seems to justify empirical beliefs about externals when there is no external input [Bonjour] |
| Full Idea: The 1st standard objection to coherence is the 'isolation problem', that contingent apparently-empirical beliefs might be justified in the absence of any informational input from the extra-conceptual world they attempt to describe. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 3.2) | |
| A reaction: False beliefs can be well justified. In a perfect virtual reality we would believe our experiences precisely because they were so coherent. Messengers from the front line have top priority, but how do you detect infiltrators and liars? |
| 8894 | Coherentists must give a reason why coherent justification is likely to lead to the truth [Bonjour] |
| Full Idea: The 3rd standard objection to coherence is the demand for a meta-justification for coherence, a reason for thinking that justification on the basis of the coherentist view of justification is in fact likely to lead to believing the truth. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 3.2) | |
| A reaction: Some coherentists respond by adopting a coherence theory of truth, which strikes me as extremely unwise. There must be an underlying optimistic view, centred on the principle of sufficient reason, that reality itself is coherent. I like Idea 8618. |
| 8889 | Reliabilists disagree over whether some further requirement is needed to produce knowledge [Bonjour] |
| Full Idea: Reliabilist views differ among themselves with regard to whether a belief's being produced in a reliable way is by itself sufficient for epistemic justification or whether there are further requirements that must be satisfied as well. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 2.1) | |
| A reaction: If 'further requirements' are needed, the crucial question would be which one is trumps when they clash. If the further requirements can correct the reliable source, then it cannot any longer be called 'reliabilism'. It's Further-requirement-ism. |
| 8890 | If the reliable facts producing a belief are unknown to me, my belief is not rational or responsible [Bonjour] |
| Full Idea: How can the fact that a belief is reliably produced make my acceptance of that belief rational and responsible when that fact itself is entirely unavailable to me? | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 2.2) | |
| A reaction: This question must rival Pollock's proposal (Idea 8815) as the master argument against externalism. Bonjour is assuming that knowledge has to be 'rational and responsible', but clearly externalists take a more lax view of knowledge. |
| 8895 | If neither the first-level nor the second-level is itself conscious, there seems to be no consciousness present [Bonjour] |
| Full Idea: In the higher-order thought theory of consciousness, if the first-order thought is not itself conscious and the second-order thought is not itself conscious, then there seems to be no consciousness of the first-level content present at all. | |
| From: Laurence Bonjour (A Version of Internalist Foundationalism [2003], 4.2) | |
| A reaction: A nice basic question. The only plausible answer seems to be that consciousness arises out of the combination of levels. Otherwise one of the levels is redundant, or we are facing a regress. |
| 11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
| Full Idea: The standard view is that affirming not-A is more complex than affirming the atomic sentence A itself, with the latter determining its sense. But we could learn 'not' directly, by learning at once how to either affirm A or reject A. | |
| From: Ian Rumfitt ("Yes" and "No" [2000], IV) | |
| A reaction: [compressed] This seems fairly anti-Fregean in spirit, because it looks at the psychology of how we learn 'not' as a way of clarifying what we mean by it, rather than just looking at its logical behaviour (and thus giving it a secondary role). |