14 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) |
| 17644 | Metaphysical realism is committed to there being one ultimate true theory [Putnam] |
| Full Idea: What makes the metaphysical realist a 'metaphysical' realist is his belief that there is somewhere 'one true theory' (two theories which are true and complete descriptions of the world would be mere notational variants of each other). | |
| From: Hilary Putnam (Why there isn't a ready-made world [1981], 'Causation') | |
| A reaction: This is wrong!!!!! Commitment to one reality doesn't imply that only one comprehensive theory is possible. Theory-making (at least in any human language, or in mathematics) is an inherently limited activity. |
| 17648 | It is an illusion to think there could be one good scientific theory of reality [Putnam] |
| Full Idea: The idea of a coherent theory of the noumena; consistent, systematic, and arrived at by 'the scientific method' seems to me to be chimerical. | |
| From: Hilary Putnam (Why there isn't a ready-made world [1981], 'Failure') | |
| A reaction: I sort of agree with this, but it definitely doesn't make me an anti-realist. |
| 17643 | Shape is essential relative to 'statue', but not essential relative to 'clay' [Putnam] |
| Full Idea: Relative to the description 'that statue', a certain shape is an essential property of the object; relative to the description 'that piece of clay', the shape not an essential property (but being clay is). | |
| From: Hilary Putnam (Why there isn't a ready-made world [1981], 'Intro') | |
| A reaction: Relative to the description 'that loathsome object', is the statue essentially loathsome? Asserting the essence of an object is a response to the object, not a response to a description of it. This is not the solution to the statue problem. |
| 17642 | The old view that sense data are independent of mind is quite dotty [Putnam] |
| Full Idea: Moore and Russell held the strange view that 'sensibilia' (sense data) are mind-independent entities: a view so dotty, on the face of it, that few analytic philosophers like to be reminded that this is how analytic philosophy started. | |
| From: Hilary Putnam (Why there isn't a ready-made world [1981], 'Intro') | |
| A reaction: I suspect the view was influenced by the anti-psychologism of Frege, and his idea that all the other concepts are mind-independent, living by their own rules in a 'third realm'. Personally I think analytic philosophy needs more psychology, not less. |
| 8433 | There are few traces of an event before it happens, but many afterwards [Lewis, by Horwich] |
| Full Idea: Lewis claims that most events are over-determined by subsequent states of the world, but not by their history. That is, the future of every event contains many independent traces of its occurrence, with little prior indication that it would happen. | |
| From: report of David Lewis (Counterfactual Dependence and Time's Arrow [1979]) by Paul Horwich - Lewis's Programme p.209 | |
| A reaction: Lewis uses this asymmetry to deduce the direction of causation, and hence the direction of time. Most people (including me, I think) would prefer to use the axiomatic direction of time to deduce directions of causation. Lewis was very wicked. |
| 17645 | An alien might think oxygen was the main cause of a forest fire [Putnam] |
| Full Idea: Imagine a Venusian lands on Earth and observes a forest fire, and says 'I know what caused that - the atmosphere is saturated with oxygen!'. Thus one man's 'background condition' can easily be another man's 'cause'. | |
| From: Hilary Putnam (Why there isn't a ready-made world [1981], 'Causation') | |
| A reaction: You can't sweep 'the' cause of a fire away so easily. There is always oxygen on Earth, but only occasional forest fires. The oxygen doesn't 'trigger' the fire (i.e. it isn't the proximate cause). |