Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'Bayesianism' and 'The Establishment of Scientific Semantics'

expand these ideas     |    start again     |     specify just one area for these texts

20 ideas

2. Reason / D. Definition / 3. Types of Definition
13838 A decent modern definition should always imply a semantics [Hacking]
3. Truth / F. Semantic Truth / 1. Tarski's Truth / a. Tarski's truth definition
13338 '"It is snowing" is true if and only if it is snowing' is a partial definition of the concept of truth [Tarski]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
13834 Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
13835 Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking]
13833 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
13845 The various logics are abstractions made from terms like 'if...then' in English [Hacking]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
13840 First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
13844 A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking]
5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
13337 A language: primitive terms, then definition rules, then sentences, then axioms, and finally inference rules [Tarski]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
13842 Second-order completeness seems to need intensional entities and possible worlds [Hacking]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
13837 With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
13839 Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
13335 Semantics is the concepts of connections of language to reality, such as denotation, definition and truth [Tarski]
13336 A language containing its own semantics is inconsistent - but we can use a second language [Tarski]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
13339 A sentence is satisfied when we can assert the sentence when the variables are assigned [Tarski]
13340 Satisfaction is the easiest semantical concept to define, and the others will reduce to it [Tarski]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
13843 If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
5. Theory of Logic / K. Features of Logics / 2. Consistency
13341 Using the definition of truth, we can prove theories consistent within sound logics [Tarski]
14. Science / C. Induction / 6. Bayes's Theorem
2799 Bayes' theorem explains why very surprising predictions have a higher value as evidence [Horwich]
2798 Probability of H, given evidence E, is prob(H) x prob(E given H) / prob(E) [Horwich]