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5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic

[broad views about different systems of logic]

33 ideas
If we utter three steps of a logical argument, they never exist together [Sext.Empiricus]
Logic has precise boundaries, and is the formal rules for all thinking [Kant]
Frege has a judgement stroke (vertical, asserting or judging) and a content stroke (horizontal, expressing) [Weiner on Frege]
The laws of logic are boundless, so we want the few whose power contains the others [Frege]
Subject-predicate logic (and substance-attribute metaphysics) arise from Aryan languages [Russell]
There are several logics, none of which will ever derive falsehoods from truth [Lewis,CI]
In logic nothing is hidden [Wittgenstein]
We can dispense with self-evidence, if language itself prevents logical mistakes [Wittgenstein]
Logic studies consequence, compatibility, contradiction, corroboration, necessitation, grounding.... [Ryle]
In order to select the logic justified by experience, we would need to use a lot of logic [Boghossian on Quine]
My logical grammar has sentences by predication, then negation, conjunction, and existential quantification [Quine]
We can base logic on acceptability, and abandon the Fregean account by truth-preservation [Ellis]
Deduction is justified by the semantics of its metalanguage [Hanna on Dummett]
Inference not from content, but from the fact that it was said, is 'conversational implicature' [Enderton]
If complex logic requires rules, then so does basic logic [Searle]
We have a theory of logic (implication and inconsistency), but not of inference or reasoning [Harman]
Any two states are logically linked, by being entailed by their conjunction [Harman]
Logic is either for demonstration, or for characterizing structures [Tharp]
Topos theory explains the plurality of possible logics [Badiou]
Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W]
Logic is based on transitions between sentences [Prawitz]
The two main views in philosophy of logic are extensionalism and intensionalism [Jacquette]
Logic describes inferences between sentences expressing possible properties of objects [Jacquette]
Situation theory is logic that takes account of context [Devlin]
There is no 'correct' logic for natural languages [Shapiro]
Logic is the ideal for learning new propositions on the basis of others [Shapiro]
There is a real issue over what is the 'correct' logic [Sider]
'It is raining' and 'it is not raining' can't be legislated, so we can't legislate 'p or p' [Sider]
Logic studies consequence; logical truths are consequences of everything, or nothing [Beall/Restall]
Syllogisms are only logic when they use variables, and not concrete terms [Beall/Restall]
To determine the patterns in logic, one must identify its 'building blocks' [Walicki]
If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt]
Logic is higher-order laws which can expand the range of any sort of deduction [Rumfitt]