13 ideas
14249 | Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley] |
10830 | Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos] |
10829 | A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos] |
10832 | '∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos] |
10834 | Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos] |
13841 | Why should compactness be definitive of logic? [Boolos, by Hacking] |
10833 | Many concepts can only be expressed by second-order logic [Boolos] |
18284 | Particulars can be verified or falsified, but general statements can only be falsified (conclusively) [Popper] |
22098 | Socrates neglects the gap between knowing what is good and doing good [Kierkegaard, by Carlisle] |
22096 | Anxiety is not a passing mood, but a response to human freedom [Kierkegaard, by Carlisle] |
22097 | The ultimate in life is learning to be anxious in the right way [Kierkegaard] |
21909 | Ultimate knowledge is being anxious in the right way [Kierkegaard] |
20758 | Anxiety is staring into the yawning abyss of freedom [Kierkegaard] |