Combining Texts

All the ideas for 'works (all lost)', 'On the Ultimate Origination of Things' and 'On Second-Order Logic'

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


14 ideas

1. Philosophy / A. Wisdom / 1. Nature of Wisdom
Wisdom involves the desire to achieve perfection [Leibniz]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
5. Theory of Logic / C. Ontology of Logic / 1. Ontology of Logic
A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
'∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
5. Theory of Logic / K. Features of Logics / 4. Completeness
Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
Why should compactness be definitive of logic? [Boolos, by Hacking]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Many concepts can only be expressed by second-order logic [Boolos]
7. Existence / A. Nature of Existence / 5. Reason for Existence
Leibniz first asked 'why is there something rather than nothing?' [Leibniz, by Jacquette]
There must be a straining towards existence in the essence of all possible things [Leibniz]
Because something does exist, there must be a drive in possible things towards existence [Leibniz]
10. Modality / A. Necessity / 7. Natural Necessity
The world is physically necessary, as its contrary would imply imperfection or moral absurdity [Leibniz]
20. Action / C. Motives for Action / 3. Acting on Reason / a. Practical reason
We follow the practical rule which always seeks maximum effect for minimum cost [Leibniz]
26. Natural Theory / A. Speculations on Nature / 1. Nature
The principle of determination in things obtains the greatest effect with the least effort [Leibniz]