20 ideas
18951 | For scientific purposes there is a precise concept of 'true-in-L', using set theory [Putnam] |
18953 | Modern notation frees us from Aristotle's restriction of only using two class-names in premises [Putnam] |
18949 | The universal syllogism is now expressed as the transitivity of subclasses [Putnam] |
18952 | '⊃' ('if...then') is used with the definition 'Px ⊃ Qx' is short for '¬(Px & ¬Qx)' [Putnam] |
18958 | In type theory, 'x ∈ y' is well defined only if x and y are of the appropriate type [Putnam] |
10779 | A comprehension axiom is 'predicative' if the formula has no bound second-order variables [Linnebo] |
18954 | Before the late 19th century logic was trivialised by not dealing with relations [Putnam] |
10781 | A 'pure logic' must be ontologically innocent, universal, and without presuppositions [Linnebo] |
18956 | Asserting first-order validity implicitly involves second-order reference to classes [Putnam] |
18962 | Unfashionably, I think logic has an empirical foundation [Putnam] |
18961 | We can identify functions with certain sets - or identify sets with certain functions [Putnam] |
10778 | Can second-order logic be ontologically first-order, with all the benefits of second-order? [Linnebo] |
10783 | Plural quantification depends too heavily on combinatorial and set-theoretic considerations [Linnebo] |
18955 | Having a valid form doesn't ensure truth, as it may be meaningless [Putnam] |
18959 | Sets larger than the continuum should be studied in an 'if-then' spirit [Putnam] |
18957 | Nominalism only makes sense if it is materialist [Putnam] |
10782 | The modern concept of an object is rooted in quantificational logic [Linnebo] |
18950 | Physics is full of non-physical entities, such as space-vectors [Putnam] |
18960 | Most predictions are uninteresting, and are only sought in order to confirm a theory [Putnam] |
19384 | Space and time are the order of all possibilities, and don't just relate to what is actual [Leibniz] |