54 ideas
| 5300 | Philosophers have interpreted the world, but the point is to change it [Marx] |
| 5750 | Consistency is modal, saying propositions are consistent if they could be true together [Melia] |
| 5297 | Whether human thinking can be 'true' must be decided in practice, not theory [Marx] |
| 5737 | Predicate logic has connectives, quantifiers, variables, predicates, equality, names and brackets [Melia] |
| 5744 | First-order predicate calculus is extensional logic, but quantified modal logic is intensional (hence dubious) [Melia] |
| 11022 | Gentzen introduced a natural deduction calculus (NK) in 1934 [Gentzen, by Read] |
| 11065 | The inferential role of a logical constant constitutes its meaning [Gentzen, by Hanna] |
| 11023 | The logical connectives are 'defined' by their introduction rules [Gentzen] |
| 11213 | Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen] |
| 5740 | Second-order logic needs second-order variables and quantification into predicate position [Melia] |
| 13832 | Natural deduction shows the heart of reasoning (and sequent calculus is just a tool) [Gentzen, by Hacking] |
| 5741 | If every model that makes premises true also makes conclusion true, the argument is valid [Melia] |
| 10067 | Gentzen proved the consistency of arithmetic from assumptions beyond arithmetic [Gentzen, by Musgrave] |
| 5735 | Maybe names and predicates can capture any fact [Melia] |
| 5736 | No sort of plain language or levels of logic can express modal facts properly [Melia] |
| 5746 | The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities [Melia] |
| 5738 | We may be sure that P is necessary, but is it necessarily necessary? [Melia] |
| 5732 | 'De re' modality is about things themselves, 'de dicto' modality is about propositions [Melia] |
| 5739 | Sometimes we want to specify in what ways a thing is possible [Melia] |
| 5734 | Possible worlds make it possible to define necessity and counterfactuals without new primitives [Melia] |
| 5742 | In possible worlds semantics the modal operators are treated as quantifiers [Melia] |
| 5743 | If possible worlds semantics is not realist about possible worlds, logic becomes merely formal [Melia] |
| 5749 | Possible worlds could be real as mathematics, propositions, properties, or like books [Melia] |
| 5751 | The truth of propositions at possible worlds are implied by the world, just as in books [Melia] |
| 22598 | The authentic self exists at the level of class, rather than the individual [Marx, by Dunt] |
| 5748 | We accept unverifiable propositions because of simplicity, utility, explanation and plausibility [Melia] |
| 5298 | The human essence is not found in individuals but in social relations [Marx] |
| 23874 | Armies and businesses create moralities in which their activity can do no wrong [Marx, by Weil] |
| 22001 | The real will of the cooperative will replace the 'will of the people' [Marx] |
| 21991 | The middle class gain freedom through property, but workers can only free all of humanity [Marx, by Singer] |
| 21990 | Theory is as much a part of a revolution as material force is [Marx] |
| 22971 | In moving from capitalism to communism a revolutionary dictatorship of the proletariat is needed [Marx] |
| 18662 | Liberal freedom is the right to be separate, and ignores the union of man with man [Marx] |
| 23372 | Liberals want the right to be separate, rather than for people to be united [Marx] |
| 20576 | Early Marx anticipates communitarian objections to liberalism [Marx, by Oksala] |
| 21989 | Man is dominated by money, which is the essence of his alienation [Marx] |
| 22000 | From each according to his ability, to each according to his need [Marx] |
| 23862 | By saying the material dialectic of history aspires to the best, Marx agreed with capitalism [Weil on Marx] |
| 21999 | False consciousness results from concealment by the superstructure [Marx, by Singer] |
| 23875 | Marx says force is everything, and that the weak will become strong, while remaining the weak [Weil on Marx] |
| 21995 | Must production determine superstructure, or could it be the other way round? [Singer on Marx] |
| 18653 | Marx rejected equal rights because they never actually treat people as equals [Marx, by Kymlicka] |
| 20577 | Even decently paid workers still have their produce bought with money stolen from them [Marx] |
| 22969 | People who only have their labour power are the slaves of those permitting them to work [Marx] |
| 21996 | Freedom only comes when labour is no longer necessary [Marx] |
| 22970 | Freedom is making the state subordinate to its society [Marx] |
| 21994 | The handmill gives feudalism, the steam mill capitalism [Marx] |
| 20958 | Capitalism changes the world, by socialising the idea of a commodity [Marx, by Bowie] |
| 23876 | The essence of capitalism is the subordination of people to things [Marx, by Weil] |
| 20960 | Marx thought capitalism was partly liberating, and could make labour and ownership more humane [Marx, by Bowie] |
| 22972 | Bourgeois 'freedom of conscience' just tolerates all sorts of religious intolerance [Marx] |
| 20519 | Marxists say liberal rights are confrontational, and liberal equality is a sham [Marx, by Wolff,J] |
| 7128 | Religion is the opium of the people, and real happiness requires its abolition [Marx] |
| 5299 | Religious feeling is social in origin [Marx] |