20 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) |
| 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. |
| 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) |
| 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. |
| 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. |
| 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) |
| 2590 | Dispositions need mental terms to define them [Putnam] |
| Full Idea: The chief difficulty with the behaviour-disposition account is the virtual impossibility of specifying a disposition except as a 'disposition of x to behave as though x were in pain'. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.57) | |
| A reaction: This has become the best-known objection to behaviourism - that you can't specify a piece of behaviour clearly unless you mention the mental state which it is expressing. The defence is to go on endlessly mentioning further behaviour. |
| 2591 | Total paralysis would mean that there were mental states but no behaviour at all [Putnam] |
| Full Idea: Two animals with all motor nerves cut will have the same actual and potential behaviour (i.e. none), but if only one has uncut pain fibres, it will feel pain where the other won't. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.57) | |
| A reaction: This is a splendidly literal and practical argument against behaviourism - if you prevent all the behaviour, you don't thereby prevent the experience. Clearly we have to say something about what is inside the 'black box' of the mind. |
| 2588 | Is pain a functional state of a complete organism? [Putnam] |
| Full Idea: I propose the hypothesis that pain, or the state of being in pain, is a functional state of a whole organism. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.54) | |
| A reaction: This sounds wrong right from the start. Pain hurts. The fact that it leads to avoidance behaviour etc. seems much more like a by-product of pain than its essence. |
| 2589 | Functionalism is compatible with dualism, as pure mind could perform the functions [Putnam] |
| Full Idea: The functional-state hypothesis is not incompatible with dualism, as a system consisting of a body and a soul could meet the required conditions. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.55) | |
| A reaction: He doesn't really believe this, of course. This claim led to all the weak objections to functionalism involving silly implementations of minds. A brain is the only plausible way to implement our mental functions. |
| 2592 | Functional states correlate with AND explain pain behaviour [Putnam] |
| Full Idea: The presence of a certain functional state is not merely 'correlated with' but actually explains the pain behaviour on the part of the organism. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.58) | |
| A reaction: Does it offer any further explanation beyond saying that it is the brain state that causes the behaviour? The pain is just a link between damage and avoidance. I wish that is all that pain was. |
| 2587 | Temperature is mean molecular kinetic energy, but they are two different concepts [Putnam] |
| Full Idea: The concept of temperature is not the same as the concept of mean molecular kinetic energy. But temperature is mean molecular kinetic energy. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.52) | |
| A reaction: This is the standard analogy for mind-brain identity, and it seems fair enough to me. The mind is the activity of the brain. It is rather unhelpful to think of weather in terms of chemistry, but it is actions of chemicals. |
| 6376 | Neuroscience does not support multiple realisability, and tends to support identity [Polger on Putnam] |
| Full Idea: Putnam was too quick to assert neuroscientific support for multiple realizability; current evidence does not reveal it, and there is some reason to think the enterprises of neuroscience are premised on the hypothesis of brain-state identity. | |
| From: comment on Hilary Putnam (The Nature of Mental States [1968]) by Thomas W. Polger - Natural Minds Ch.1.4 | |
| A reaction: I have always been suspicious of the glib claim that mental states were multiply realisable. I see no reason to think that octupi see colours as we do, or experience fear as we do, even though their behaviour has to be similar, for survival. |
| 2330 | If humans and molluscs both feel pain, it can't be a single biological state [Putnam, by Kim] |
| Full Idea: Mental states have vastly diverse physical/biological realizations in different species and structures (e.g. pain in humans and in molluscs), so no mental state can be identified with any single physical/biological state. | |
| From: report of Hilary Putnam (The Nature of Mental States [1968]) by Jaegwon Kim - Mind in a Physical World n p.120 | |
| A reaction: But maybe mollusc and human nervous systems ARE the same in the respects that matter. We don't know enough about pain to deny that possibility. |
| 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). |