31 ideas
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| 3993 | Arguments are nearly always open to challenge, but they help to explain a position rather than force people to believe [Lewis] |
| 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] |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| 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] |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| 3990 | The whole truth supervenes on the physical truth [Lewis] |
| 3991 | Where pixels make up a picture, supervenience is reduction [Lewis] |
| 3995 | A mind is an organ of representation [Lewis] |
| 3994 | Human pain might be one thing; Martian pain might be something else [Lewis] |
| 3989 | I am a reductionist about mind because I am an a priori reductionist about everything [Lewis] |
| 3992 | Folk psychology makes good predictions, by associating mental states with causal roles [Lewis] |
| 3996 | Folk psychology doesn't say that there is a language of thought [Lewis] |
| 3998 | If you don't share an external world with a brain-in-a-vat, then externalism says you don't share any beliefs [Lewis] |
| 3997 | Nothing shows that all content is 'wide', or that wide content has logical priority [Lewis] |
| 3999 | A spontaneous duplicate of you would have your brain states but no experience, so externalism would deny him any beliefs [Lewis] |
| 4000 | Wide content derives from narrow content and relationships with external things [Lewis] |
| 4059 | It can't be murder for a mother to perform an abortion on herself to save her own life [Thomson] |
| 4057 | A newly fertilized ovum is no more a person than an acorn is an oak tree [Thomson] |
| 4695 | Maybe abortion can be justified despite the foetus having full human rights [Thomson, by Foot] |
| 4696 | The foetus is safe in the womb, so abortion initiates its death, with the mother as the agent. [Foot on Thomson] |
| 4060 | The right to life does not bestow the right to use someone else's body to support that life [Thomson] |
| 4061 | The right to life is not a right not to be killed, but not to be killed unjustly [Thomson] |
| 4058 | Is someone's right to life diminished if they were conceived by a rape? [Thomson] |
| 4062 | No one is morally required to make huge sacrifices to keep someone else alive for nine months [Thomson] |