10 ideas
| 9540 | A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0 [Hughes/Cresswell] |
| Full Idea: A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0. | |
| From: GE Hughes/M Cresswell (An Introduction to Modal Logic [1968], Ch.1) | |
| A reaction: In the interpreted version of the logic, 1 and 0 would become T (true) and F (false). The procedure seems to be called nowadays a 'valuation'. |
| 9541 | The Law of Transposition says (P→Q) → (¬Q→¬P) [Hughes/Cresswell] |
| Full Idea: The Law of Transposition says that (P→Q) → (¬Q→¬P). | |
| From: GE Hughes/M Cresswell (An Introduction to Modal Logic [1968], Ch.1) | |
| A reaction: That is, if the consequent (Q) of a conditional is false, then the antecedent (P) must have been false. |
| 9543 | The rules preserve validity from the axioms, so no thesis negates any other thesis [Hughes/Cresswell] |
| Full Idea: An axiomatic system is most naturally consistent iff no thesis is the negation of another thesis. It can be shown that every axiom is valid, that the transformation rules are validity-preserving, and if a wff α is valid, then ¬α is not valid. | |
| From: GE Hughes/M Cresswell (An Introduction to Modal Logic [1968], Ch.1) | |
| A reaction: [The labels 'soundness' and 'consistency' seem interchangeable here, with the former nowadays preferred] |
| 9544 | A system is 'weakly' complete if all wffs are derivable, and 'strongly' if theses are maximised [Hughes/Cresswell] |
| Full Idea: To say that an axiom system is 'weakly complete' is to say that every valid wff of the system is derivable as a thesis. ..The system is 'strongly complete' if it cannot have any more theses than it has without falling into inconsistency. | |
| From: GE Hughes/M Cresswell (An Introduction to Modal Logic [1968], Ch.1) | |
| A reaction: [They go on to say that Propositional Logic is strongly complete, but Modal Logic is not] |
| 20582 | World government needs a shared global identity [Oksala] |
| Full Idea: Critics have argued that a global 'demos' would require a shared global identity. | |
| From: Johanna Oksala (Political Philosophy: all that matters [2013], Ch.9 'Epi') | |
| A reaction: The great divisions are religion and language. The great unifiers are sport, arts and entertainment, plus basic human needs like food, health and housing. The reply is that there cannot be identity without differences, so global democracy is out. |
| 20568 | The principles Rawls arrives at do not just conform to benevolence, but also result from choices [Oksala] |
| Full Idea: The advantage of Rawls's method is that the principles the individual chooses are not only fair according to some abstract principle of benevolence, but also the result of rational choice. | |
| From: Johanna Oksala (Political Philosophy: all that matters [2013], Ch.5) | |
| A reaction: That is a very nice way of putting the beauty of Rawls's idea. In modern political philosophy you hear far more criticisms of Rawls than praise. If a philosopher is criticised a lot, it is probably because they have stated their views clearly. |
| 20578 | Anarchists prefer local and communal government [Oksala] |
| Full Idea: Anarchists advocate forms of governance such as communes and associations that are as local and close to the direct control of the people as possible. | |
| From: Johanna Oksala (Political Philosophy: all that matters [2013], Ch.8) | |
| A reaction: Which might explain why recent conservative governments have steadily eliminated local government in Britain. |
| 20574 | Utilitarianism neglects responsibility, duties and rights [Oksala] |
| Full Idea: A focus solely on utility excludes considerations of personal responsibility and duty, as well as considerations of the basic rights of individuals. | |
| From: Johanna Oksala (Political Philosophy: all that matters [2013], Ch.7) | |
| A reaction: [He cites these as the common modern criticisms] The defence is to explain the value of each of these in utilitarian terms. There is a general problem (conceded by Mill) of motivation in utilitarianism. There's not much in it for me! |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |