34 ideas
| 3695 | Philosophy is a priori if it is anything [Bonjour] |
| Full Idea: My conviction is that philosophy is a priori if it is anything. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], Pref) | |
| A reaction: How about knowledge of a posteriori necessities, such as the length of a metre, known by observation of the standard metre in Paris? |
| 19066 | Philosophy aims to understand the world, through ordinary experience and science [Dummett] |
| Full Idea: Philosophy is an attempt to understand the world, as it is revealed to us both in our ordinary experience and by the discoveries and theories of science. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.311) | |
| A reaction: I don't see a sharp division between 'ordinary' and 'scientific'. I really like this idea, first because it makes 'understanding' central, and second because it wants both revelations. In discussing matter and time, there is too much emphasis on science. |
| 3651 | Perceiving necessary connections is the essence of reasoning [Bonjour] |
| Full Idea: If one never in fact grasps any necessary connections between anything, it is hard to see what reasoning could possible amount to. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §4.3) |
| 3700 | Coherence can't be validated by appeal to coherence [Bonjour] |
| Full Idea: The epistemic authority of coherence cannot itself be established by appeal to coherence. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §3.7 n50) | |
| A reaction: The standard approach amongs modern philosophers (following, I think, Kripke) is to insist on 'intuition' as basic, despite all its problems. I have no better suggestion. |
| 8368 | A correct definition is what can be substituted without loss of meaning [Ducasse] |
| Full Idea: A definition of a word is correct if the definition can be substituted for the word being defined in an assertion without in the least changing the meaning which the assertion is felt to have. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §1) | |
| A reaction: This sounds good, but a very bland and uninformative rephrasing would fit this account, without offering anything very helpful. The word 'this' could be substituted for a lot of object words. A 'blade' is 'a thing always attached to a knife handle'. |
| 19067 | A successful proof requires recognition of truth at every step [Dummett] |
| Full Idea: For a demonstration to be cogent it is necessary that the passage from step to step involve a recognition of truth at each line. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.313) | |
| A reaction: Dummett cited Quine (esp. 1970) as having an almost entirely syntactic view of logic. Rumfitt points out that logic can move validly from one falsehood to another. Even a 'proof' might detour into falsehood, but it would not be a 'canonical' proof! |
| 19060 | Truth-tables are dubious in some cases, and may be a bad way to explain connective meaning [Dummett] |
| Full Idea: It is arguable whether two-valued truth tables give correct meanings for certain sentential operators, and even whether they constitute legitimate explanations of any possible sentential operators. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: See 'Many-valued logic' for examples of non-binary truth tables. Presumably logicians should aspire to make their semantics precise, as well as their syntax. |
| 11066 | Deduction is justified by the semantics of its metalanguage [Dummett, by Hanna] |
| Full Idea: For Dummett the semantics of the metalanguage is the external and objective source of the justification of deduction. | |
| From: report of Michael Dummett (The Justification of Deduction [1973]) by Robert Hanna - Rationality and Logic 3.4 | |
| A reaction: This is offered as an answer to the Lewis Carroll problem that justifying deduction seems to need deduction, thus leading to a regress. [There is a reply to Dummett by Susan Haack] |
| 19058 | Syntactic consequence is positive, for validity; semantic version is negative, with counterexamples [Dummett] |
| Full Idea: A plausible account is that the syntactic notion of consequence is for positive results, that some form of argument is valid; the semantic notion is required for negative results, that some argument is invalid, because a counterexample can be found. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.292) | |
| A reaction: This rings true for the two strategies of demonstration, the first by following the rules in steps, the second by using your imagination (or a tableau) to think up problems. |
| 19063 | Beth trees show semantics for intuitionistic logic, in terms of how truth has been established [Dummett] |
| Full Idea: Beth trees give a semantics for intuitionistic logic, by representing sentence meaning in terms of conditions under which it is recognised to have been established as true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) |
| 19059 | In standard views you could replace 'true' and 'false' with mere 0 and 1 [Dummett] |
| Full Idea: Nothing is lost, on this view, if in the standard semantic treatment of classical sentential logic, we replace the standard truth-values 'true' and 'false' by the numbers 0 and 1. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: [A long context will explain 'on this view'] He is discussing the relationship of syntactic and semantic consequence, and goes on to criticise simple binary truth-table accounts of connectives. Semantics on a computer would just be 0 and 1. |
| 19062 | Classical two-valued semantics implies that meaning is grasped through truth-conditions [Dummett] |
| Full Idea: The standard two-valued semantics for classical logic involves a conception under which to grasp the meaning of a sentence is to apprehend the conditions under which it is, or is not, true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) | |
| A reaction: The idea is that you only have to grasp the truth tables for sentential logic, and that needs nothing more than knowing whether a sentence is true or false. I'm not sure where the 'conditions' creep in, though. |
| 19065 | Soundness and completeness proofs test the theory of meaning, rather than the logic theory [Dummett] |
| Full Idea: A proof of soundess or completeness is a test, not so much of the logical theory to which it applies, but of the theory of meaning which underlies the semantics. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.310) | |
| A reaction: These two types of proof concern how the syntax and the semantics match up, so this claim sounds plausible, though I tend to think of them as more like roadworthiness tests for logic, checking how well they function. |
| 3697 | The concept of possibility is prior to that of necessity [Bonjour] |
| Full Idea: While necessity and possibility are interdefinable concepts, it is the idea of a possible world or situation which is intuitively primary. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §1.3) |
| 3704 | Moderate rationalists believe in fallible a priori justification [Bonjour] |
| Full Idea: Moderate rationalism preserves a priori justification, but rejects the idea that it is infallible. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §4.1) |
| 3707 | Our rules of thought can only be judged by pure rational insight [Bonjour] |
| Full Idea: Criteria or rules do not somehow apply to themselves. They must be judged by the sort of rational insight or intuition that the rationalist is advocating. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §5.2) |
| 3696 | A priori justification requires understanding but no experience [Bonjour] |
| Full Idea: A proposition will count as being justified a priori as long as no appeal to experience is needed for the proposition to be justified - once it is understood. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §1.2) | |
| A reaction: Could you 'understand' that a square cannot be circular without appeal to experience? I'm losing faith in the pure a priori. |
| 3703 | You can't explain away a priori justification as analyticity, and you can't totally give it up [Bonjour] |
| Full Idea: Moderate empiricists try unsuccessfully to explain a priori justification by means of analyticity, and radical empiricist attempts to dispense with a priori justification end in nearly total scepticism. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §4.1) | |
| A reaction: My working theory is neither of the above. Because we can abstract from the physical world, we can directly see/experience generalised (and even necessary) truths about it. |
| 3706 | A priori justification can vary in degree [Bonjour] |
| Full Idea: A priori justification can vary in degree. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §4.5) | |
| A reaction: This idea, which I trace back at least to Russell, seems to me one of breakthrough ideas in modern thought. It means that a priori knowledge can be reconnected with a posteriori knowledge. |
| 3699 | The induction problem blocks any attempted proof of physical statements [Bonjour] |
| Full Idea: The attempt to prove physical statements on the basis of sensory evidence is defeated by the problem of induction. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §3.6) | |
| A reaction: This sounds like a logician's use of the word 'prove', which would be a pretty forlorn hope. Insofar as experience proves anything, fully sensing a chair proves its existence. |
| 3701 | Externalist theories of justification don't require believers to have reasons for their beliefs [Bonjour] |
| Full Idea: An externalist theory of epistemic justification or warrant need not involve the possession by the believer of anything like a reason for thinking that their belief is true. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §3.7) | |
| A reaction: That is the problem with externalism. If the believer does not have a reason, then why would they believe? Externalists are interesting on justification, but daft about belief. Why do I believe I know something, when I can't recall how I learnt it? |
| 3702 | Externalism means we have no reason to believe, which is strong scepticism [Bonjour] |
| Full Idea: If externalism is the final story, we have no reason to think that any of our beliefs are true, which amounts to a very strong and intuitively implausible version of scepticism. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §3.7) | |
| A reaction: A very good point. I may, like a cat, know many things, with good external support, but as soon as I ask sceptical questions, I sink without trace if I lack internal reasons. |
| 3709 | Induction must go beyond the evidence, in order to explain why the evidence occurred [Bonjour] |
| Full Idea: Inductive explanations must be conceived of as something stronger than mere Humean constant conjunction; …anything less than this will not explain why the inductive evidence occurred in the first place. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §7.7) |
| 19061 | An explanation is often a deduction, but that may well beg the question [Dummett] |
| Full Idea: An explanation is often a deductive argument, with the fact needing explaining as its conclusion. ...But the conclusion is usually given in advance, and we may only believe the premisses because they plausibly explain the conclusion. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.296) | |
| A reaction: [compressed (Dummett's wordy prose cries out for it!)] I suppose this works better in mathematics, which is central to Dummett's interests. In the real world the puzzle is not usually logically implied by its explanation. |
| 3708 | All thought represents either properties or indexicals [Bonjour] |
| Full Idea: I assume that the contents of thought can be accounted for by appeal to just two general sorts of ingredient - properties (including relations) and indexicals. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §6.7) | |
| A reaction: I don't accept that relations are a type of properties. Since he does not include objects or substances, I take it that he considers objects to be bundles of properties. |
| 19064 | Holism is not a theory of meaning; it is the denial that a theory of meaning is possible [Dummett] |
| Full Idea: In the sense of giving a model for the content of a sentence, its representative power, holism is not a theory of meaning; it is the denial that a theory of meaning is possible. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.309) | |
| A reaction: This will obviously be because sentences just don't have meaning in isolation, so their meaning can't be given in terms of the sentences. |
| 3698 | Indeterminacy of translation is actually indeterminacy of meaning and belief [Bonjour] |
| Full Idea: The thesis of the indeterminacy of translation would be better described as the thesis of the indeterminacy of meaning and belief. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §3.5) | |
| A reaction: Not necessarily. It is not incoherent to believe that the target people have a coherent and stable system of meaning and belief, but finding its translation indeterminate because it is holistic, and rooted in a way of life. |
| 8367 | Causation is defined in terms of a single sequence, and constant conjunction is no part of it [Ducasse] |
| Full Idea: The correct definition of the causal relation is to be framed in terms of one single case of sequence, and constancy of conjunction is therefore no part of it. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], Intro) | |
| A reaction: This is the thesis of Ducasse's paper. I immediately warm to it. I take constant conjunction to be a consequence and symptom of causation, not its nature. There is a classic ontology/epistemology confusion to be avoided here. |
| 8372 | We see what is in common between causes to assign names to them, not to perceive them [Ducasse] |
| Full Idea: The part of a generalization concerning what is common to one individual concrete event and the causes of certain other events of the same kind is involved in the mere assigning of a name to the cause and its effect, but not in the perceiving them. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §5) | |
| A reaction: A nice point, that we should keep distinct the recognition of a cause, and the assigning of a general name to it. Ducasse is claiming that we can directly perceive singular causation. |
| 8369 | Causes are either sufficient, or necessary, or necessitated, or contingent upon [Ducasse] |
| Full Idea: There are four causal connections: an event is sufficient for another if it is its cause; an event is necessary for another if it is a condition for it; it is necessitated by another if it is an effect; it is contingent upon another if it is a resultant. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §2) | |
| A reaction: An event could be a condition for another without being necessary. He seems to have missed the indispensable aspect of a necessary condition. |
| 8373 | When a brick and a canary-song hit a window, we ignore the canary if we are interested in the breakage [Ducasse] |
| Full Idea: If a brick and the song of a canary strike a window, which breaks....we can truly say that the song of the canary had nothing to do with it, that is, in so far as what occurred is viewed merely as a case of breakage of window. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §5) | |
| A reaction: This is the germ of Davidson's view, that causation is entirely dependent on the mode of description, rather than being an actual feature of reality. If one was interested in the sound of the breakage, the canary would become relevant. |
| 8370 | A cause is a change which occurs close to the effect and just before it [Ducasse] |
| Full Idea: The cause of the particular change K was such particular change C as alone occurred in the immediate environment of K immediately before. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §3) | |
| A reaction: The obvious immediately difficulty would be overdetermination, as when it rains while I am watering my garden. The other problem would coincidence, as when I clap my hands just before a bomb goes off. |
| 8371 | Recurrence is only relevant to the meaning of law, not to the meaning of cause [Ducasse] |
| Full Idea: The supposition of recurrence is wholly irrelevant to the meaning of cause: that supposition is relevant only to the meaning of law. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §4) | |
| A reaction: This sounds plausible, especially if our notion of laws of nature is built up from a series of caused events. But we could just have an ontology of 'similar events', out of which we build laws, and 'causation' could drop out (á la Russell). |
| 8374 | We are interested in generalising about causes and effects purely for practical purposes [Ducasse] |
| Full Idea: We are interested in causes and effects primarily for practical purposes, which needs generalizations; so the interest of concrete individual facts of causation is chiefly an indirect one, as raw material for generalizations. | |
| From: Curt Ducasse (Nature and Observability of Causal Relations [1926], §6) | |
| A reaction: A nice explanation of why, if causation is fundamentally about single instances, people seem so interested in generalisations and laws. We want to predict, and we want to explain, and we want to intervene. |