12 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) |
| 8872 | It is widely supposed that externalism cannot be reconciled with first-person authority [Davidson] |
| Full Idea: It has been widely supposed that externalism, which holds that the contents of a person's propositional attitudes are partly determined by factors of which the person may be ignorant, cannot be reconciled with first-person authority. | |
| From: Donald Davidson (Epistemology Externalized [1990], p.197) | |
| A reaction: It is certainly a bit puzzling if you go around saying 'Actually, people don't know their own thoughts'. Davidson aims to defend first-person authority. The full story is developed in Tyler Burge's views on 'anti-individualism'. |
| 8874 | It is hard to interpret a speaker's actions if we take a broad view of the content [Davidson] |
| Full Idea: It will explain a speaker's actions far better if we interpret him as he intended to be interpreted, than if we suppose he means and thinks what someone else might mean and think who used the same words 'correctly'. | |
| From: Donald Davidson (Epistemology Externalized [1990], p.199) | |
| A reaction: This comes down to the fact that our actions have to be motivated by internal meanings. If I defer to experts on the essence of gold, I still buy gold according to how I myself understand it. So meaning has two components? |
| 4316 | Either all action is rational, or reason dominates, or reason is only concerned with means [Cottingham] |
| Full Idea: We can distinguish rational exclusivism (all activity is guided by reason - Plato and Spinoza), rational hegemonism (all action is dominated by reason), and rational instrumentalism (reason assesses means rather than ends - Hume). | |
| From: John Cottingham (Reason, Emotions and Good Life [2000]) | |
| A reaction: The idea that reason is the only cause of actions seems deeply implausible, but I strongly resist Hume's instrumental approach. Action without desire is not a contradiction. |
| 8873 | The cause of a usage determines meaning, but why is the microstructure of water relevant? [Davidson] |
| Full Idea: While I agree that the usual cause of the use of the word determines what it means, I do not see why sameness of microstructure is necessarily the relevant similarity that determines my reference of the word 'water'. | |
| From: Donald Davidson (Epistemology Externalized [1990], p.198) | |
| A reaction: This is a problem for essentialists who build their views on semantic considerations. But the stability of what causes 'water' thoughts is the microstructure of water. However, that is an explantion of meaning, not a definition of it. |