18 ideas
| 10688 | 'Equivocation' is when terms do not mean the same thing in premises and conclusion [Beall/Restall] |
| Full Idea: 'Equivocation' is when the terms do not mean the same thing in the premises and in the conclusion. | |
| From: JC Beall / G Restall (Logical Consequence [2005], Intro) |
| 10690 | Formal logic is invariant under permutations, or devoid of content, or gives the norms for thought [Beall/Restall] |
| Full Idea: Logic is purely formal either when it is invariant under permutation of object (Tarski), or when it has totally abstracted away from all contents, or it is the constitutive norms for thought. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) | |
| A reaction: [compressed] The third account sounds rather woolly, and the second one sounds like a tricky operation, but the first one sounds clear and decisive, so I vote for Tarski. |
| 10691 | Logical consequence needs either proofs, or absence of counterexamples [Beall/Restall] |
| Full Idea: Technical work on logical consequence has either focused on proofs, where validity is the existence of a proof of the conclusions from the premises, or on models, which focus on the absence of counterexamples. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 10695 | Logical consequence is either necessary truth preservation, or preservation based on interpretation [Beall/Restall] |
| Full Idea: Two different views of logical consequence are necessary truth-preservation (based on modelling possible worlds; favoured by Realists), or truth-preservation based on the meanings of the logical vocabulary (differing in various models; for Anti-Realists). | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) | |
| A reaction: Thus Dummett prefers the second view, because the law of excluded middle is optional. My instincts are with the first one. |
| 10689 | A step is a 'material consequence' if we need contents as well as form [Beall/Restall] |
| Full Idea: A logical step is a 'material consequence' and not a formal one, if we need the contents as well as the structure or form. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 2) |
| 10696 | A 'logical truth' (or 'tautology', or 'theorem') follows from empty premises [Beall/Restall] |
| Full Idea: If a conclusion follows from an empty collection of premises, it is true by logic alone, and is a 'logical truth' (sometimes a 'tautology'), or, in the proof-centred approach, 'theorems'. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 4) | |
| A reaction: These truths are written as following from the empty set Φ. They are just implications derived from the axioms and the rules. |
| 10693 | Models are mathematical structures which interpret the non-logical primitives [Beall/Restall] |
| Full Idea: Models are abstract mathematical structures that provide possible interpretations for each of the non-logical primitives in a formal language. | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 10692 | Hilbert proofs have simple rules and complex axioms, and natural deduction is the opposite [Beall/Restall] |
| Full Idea: There are many proof-systems, the main being Hilbert proofs (with simple rules and complex axioms), or natural deduction systems (with few axioms and many rules, and the rules constitute the meaning of the connectives). | |
| From: JC Beall / G Restall (Logical Consequence [2005], 3) |
| 1635 | Mathematics reduces to set theory (which is a bit vague and unobvious), but not to logic proper [Quine] |
| Full Idea: Mathematics reduces only to set theory, and not to logic proper… but set theory cannot claim the same firmness and obviousness as logic. | |
| From: Willard Quine (Epistemology Naturalized [1968], p.69-70) |
| 16698 | Days exist, and yet they seem to be made up of parts which don't exist [Burley] |
| Full Idea: I grant that a successive being is composed out of non-beings, as is clear of a day, which is composed of non-entities. Some part of this day is past and some future, and yet this day is. | |
| From: Walter Burley (Commentary on 'Physics' [1325], III text 11,f.65rb), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 18.3 | |
| A reaction: The dilemma of Aristotle over time infected the scholastic attempt to give an account of successive entities. A day is a wonderfully elusive entity for a metaphysician. |
| 16690 | Unlike permanent things, successive things cannot exist all at once [Burley] |
| Full Idea: This is the difference between permanent and successive things: that a permanent thing exists all at once, or at least can exist all at once, whereas it is incompatible with a successive thing to exist all at once. | |
| From: Walter Burley (Commentary on 'Physics' [1325], III txt 11,f.65rb), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 18.1 | |
| A reaction: Permanent things sound like what are now called 'three-dimensional' objects, but scholastic 'entia successiva' are not the same as spacetime 'worms' or collections of temporal stages. |
| 7627 | You can't reduce epistemology to psychology, because that presupposes epistemology [Maund on Quine] |
| Full Idea: There is something seriously misguided about Quine's project of reducing epistemology to psychology, since psychology, like any of the natural sciences, presupposes an epistemology. | |
| From: comment on Willard Quine (Epistemology Naturalized [1968]) by Barry Maund - Perception Ch.1 | |
| A reaction: I wonder if epistemology presupposes psychology? Belief, for example, is a category of folk psychology, which could be challenged. There is a quiet battle going on between philosophy and science. |
| 8871 | We should abandon a search for justification or foundations, and focus on how knowledge is acquired [Quine, by Davidson] |
| Full Idea: Quine is suggesting that philosophy should abandon the attempt to provide a foundation for knowledge, or otherwise justify it, and should instead give an account of how knowledge is acquired. | |
| From: report of Willard Quine (Epistemology Naturalized [1968]) by Donald Davidson - Epistemology Externalized p.193 | |
| A reaction: If you are going to explain how 'knowledge' is acquired, you'd better know what knowledge is. My suspicion is that Quine would be quite happy (in the pragmatist tradition) to just focus on belief, and forget about knowledge entirely. |
| 8826 | If we abandon justification and normativity in epistemology, we must also abandon knowledge [Kim on Quine] |
| Full Idea: Quine asks us to set aside the entire framework of justification-centered epistemology, ..and repudiate normativity. ..But then knowledge itself drops out of epistemology, for our concept of knowledge is inseparably tied to that of justification. | |
| From: comment on Willard Quine (Epistemology Naturalized [1968]) by Jaegwon Kim - What is 'naturalized epistemology'? p.305 | |
| A reaction: Presumably this would not bother Quine, who wants to hand so-called 'epistemology' over to the psychologists. A psychological account of belief seems plausible. Presumably false beliefs could only be pragmatically characterised. |
| 8827 | Without normativity, naturalized epistemology isn't even about beliefs [Kim on Quine] |
| Full Idea: If normativity is wholly excluded from naturalized epistemology it cannot even be thought of as being about beliefs. | |
| From: comment on Willard Quine (Epistemology Naturalized [1968]) by Jaegwon Kim - What is 'naturalized epistemology'? p.306 | |
| A reaction: And if it doesn't refer to beliefs, it certainly doesn't refer to knowledge. One might try to subsume normativity under evolutionary pragmatic 'drives', or something. Quine's project would then become wildly speculative, and hence boring. |
| 8899 | Epistemology is a part of psychology, studying how our theories relate to our evidence [Quine] |
| Full Idea: Epistemology falls into place as a chapter of psychology, and hence of natural science. ..We study meagre input and torrential output, to see how evidence relates to theory, and in what ways one's theory of nature transcends any available evidence. | |
| From: Willard Quine (Epistemology Naturalized [1968], p.83) | |
| A reaction: It depends what you are interested in. If you just want to know what makes humans tick, then Quine is your man, but if you want to know things in general, and want to know how to get it right, then the normative side of epistemology is unavoidable. |
| 8898 | Inculcations of meanings of words rests ultimately on sensory evidence [Quine] |
| Full Idea: All inculcation of meanings of words must rest ultimately on sensory evidence. | |
| From: Willard Quine (Epistemology Naturalized [1968], p.75) | |
| A reaction: This betrays Quine's behaviourist tendencies, and rules out introspection, definitions and inferences. Quine's conclusion is fairly total scepticism about meaning, but that is not surprising, given his external and meaningless starting point. |
| 8900 | In observation sentences, we could substitute community acceptance for analyticity [Quine] |
| Full Idea: Perhaps the controversial notion of analyticity can be dispensed with, in our definition of observation sentences, in favour of the straightforward attitude of community-wide acceptance. | |
| From: Willard Quine (Epistemology Naturalized [1968], p.86) | |
| A reaction: That might be a reasonable account of 'bachelors'. If the whole community accepts 'God exists', does that make it analytic? If a whole (small!) community claims to actually observe a ghost or a flying saucer, is that then analytic? |