23 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] |
| 9406 | A class is natural when everybody can spot further members of it [Quinton] |
| Full Idea: To say that a class is natural is to say that when some of its members are shown to people they pick out others without hesitation and in agreement. | |
| From: Anthony Quinton (The Nature of Things [1973], 9 'Nat') | |
| A reaction: He concedes a number of problems with his view, but I admire his attempt to at least begin to distinguish the natural (real!) classes from the ersatz ones. A mention of causal powers would greatly improve his story. |
| 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] |
| 15730 | Extreme nominalists say all classification is arbitrary convention [Quinton] |
| Full Idea: Pure, extreme nominalism sees all classification as the product of arbitrary convention. | |
| From: Anthony Quinton (The Nature of Things [1973], 9 'Nat') | |
| A reaction: I'm not sure what the word 'arbitrary' is doing there. Nominalists are not daft, and if they can classify any way they like, they are not likely to choose an 'arbitrary' system. Pragmatism tells the right story here. |
| 15728 | The naturalness of a class depends as much on the observers as on the objects [Quinton] |
| Full Idea: The naturalness of a class depends as essentially on the nature of the observers who classify as it does on the nature of the objects that they classify. ...It depends on our perceptual apparatus, and on our relatively mutable needs and interests. | |
| From: Anthony Quinton (The Nature of Things [1973], 9 'Nat') | |
| A reaction: This seems to translate 'natural' as 'natural for us', which is not much use to scientists, who spend quite a lot of effort combating folk wisdom. Do desirable sports cars constitute a natural class? |
| 9407 | Properties imply natural classes which can be picked out by everybody [Quinton] |
| Full Idea: To say there are properties is to say there are natural classes, classes introduction to some of whose members enables people to pick out others without hesitation and in agreement. | |
| From: Anthony Quinton (The Nature of Things [1973], 9 'Nat') | |
| A reaction: Aristotle would like this approach, but it doesn't find many friends among modern logician/philosophers. We should go on to ask why people agree on these things. Causal powers will then come into it. |
| 15729 | Uninstantiated properties must be defined using the instantiated ones [Quinton] |
| Full Idea: Properties that have no concrete instances must be defined in terms of those that have. | |
| From: Anthony Quinton (The Nature of Things [1973], 9 'Nat') | |
| A reaction: I wonder what the dodo used to smell like? |
| 8520 | An individual is a union of a group of qualities and a position [Quinton, by Campbell,K] |
| Full Idea: Quinton proposes that an individual is a union of a group of qualities and a position. | |
| From: report of Anthony Quinton (The Nature of Things [1973], Pt I) by Keith Campbell - The Metaphysic of Abstract Particulars §5 | |
| A reaction: This seems the obvious defence of a bundle account of objects against the charge that indiscernibles would have to be identical. It introduces, however, 'positions' into the ontology, but maybe that price must be paid. Materialism needs space. |
| 3926 | The human heart has a natural concern for public good [Hume] |
| Full Idea: While the human heart is compounded of the same elements as at present, it will never be wholly indifferent to public good. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], IX.I.222) | |
| A reaction: Even criminals can be patriotic. Why do people dump rubbish in beauty spots? |
| 3929 | No moral theory is of any use if it doesn't serve the interests of the individual concerned [Hume] |
| Full Idea: What theory of morals can ever serve any useful purpose, unless it can show, by a particular detail, that all the duties which it recommends, are also the true interest of each individual? | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], IX.II.228) | |
| A reaction: It is hard to disagree, even if occasional cases of extreme altruism can occur. |
| 3925 | Personal Merit is the possession of useful or agreeable mental qualities [Hume] |
| Full Idea: Personal Merit consists altogether in the possession of mental qualities, useful or agreeable to the person himself or to others. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], IX.I.217) | |
| A reaction: If pleasure and utility can be intrinsically valuable, why can't virtue be as well? |
| 23560 | If we all naturally had everything we could ever desire, the virtue of justice would be irrelevant [Hume] |
| Full Idea: Suppose nature has bestowed on humans such abundance of external conveniences that every individual is fully provided with whatever his appetites can want. …Justice, in that case, would be totally useless, and have no place in the catalogue of virtues. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], I.III.145) | |
| A reaction: [compressed] This seems to emphasise possessions and satisfaction of appetites, but presumably it would also need total security from other humans, which nature might struggle to provide. No sharing in this imagined world. |
| 3922 | Justice only exists to support society [Hume] |
| Full Idea: The necessity of justice to the support of society is the sole foundation of that virtue. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], III.II.163) | |
| A reaction: A sense of fairness precedes the building of a society, rather than arising out of it. |
| 3918 | Moral philosophy aims to show us our duty [Hume] |
| Full Idea: The end of all moral speculations is to teach us our duty. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], I.136) | |
| A reaction: A surprising view from someone who thinks morals are basically sentiment. |
| 3919 | Conclusions of reason do not affect our emotions or decisions to act [Hume] |
| Full Idea: Inference and conclusions of the understanding have no hold of the affections nor set in motion the active powers of man. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], I.136) | |
| A reaction: I disagree. This is a typical empiricist separation of ideas from experience, of inner from outer, of analytic from synthetic. |
| 3928 | Virtue just requires careful calculation and a preference for the greater happiness [Hume] |
| Full Idea: The sole trouble which virtue demands is that of just calculation, and a steady preference for the greater happiness. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], IX.II.228) | |
| A reaction: Hume was the parent of utilitarianism. Can one person exhibit virtue on a desert island? |
| 3923 | No one would cause pain to a complete stranger who happened to be passing [Hume] |
| Full Idea: Would any man, who is walking along, tread as willingly on another's gouty toes, whom he has no quarrel with, as on the hard flint and pavement? | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], V.II.183) | |
| A reaction: He is right that we empathise with the pain of others, and this is presumably one of the bases of morality. Animals lack sympathy for other animals. |
| 3924 | Nature makes private affections come first, because public concerns are spread too thinly [Hume] |
| Full Idea: It is wisely ordained by nature, that private connexions should commonly prevail over universal views and considerations; otherwise our affections and actions would be dissipated and lost, for want of a proper limited object. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], V.II.186n) | |
| A reaction: A very good objection to the excessively altruistic demands of utilitarianism. |
| 3921 | The safety of the people is the supreme law [Hume] |
| Full Idea: The safety of the people is the supreme law. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], III.II.157) | |
| A reaction: No political system ever seems able to disagree with this. |
| 3927 | Society prefers helpful lies to harmful truth [Hume] |
| Full Idea: Truths which are pernicious to society, if any such there be, will yield to errors which are salutary and advantageous. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], IX.II.228) | |
| A reaction: Hume probably meant religion. Two centuries later we have a greater appetite for uncomfortable truth. |
| 3920 | If you equalise possessions, people's talents will make them unequal again [Hume] |
| Full Idea: Render possessions ever so equal, men's different degrees of art, care, and industry will immediately break that equality. | |
| From: David Hume (Enquiry concerning Principles of Morals [1751], III.II.155) | |
| A reaction: This might not be so if there is a totalitarian restriction of economic freedom. |