4 ideas
| 17743 | De Morgan introduced a 'universe of discourse', to replace Boole's universe of 'all things' [De Morgan, by Walicki] |
| Full Idea: In 1846 De Morgan introduced the enormously influential notion of a possibly arbitrary and stipulated 'universe of discourse'. It replaced Boole's original - and metaphysically a bit suspect - universe of 'all things'. | |
| From: report of Augustus De Morgan (works [1846]) by Michal Walicki - Introduction to Mathematical Logic History D.1.1 | |
| A reaction: This not only brings formal logic under control, but also reflects normal talk, because there is always an explicit or implicit domain of discourse when we talk. Of virtually any conversation, you can say what it is 'about'. |
| 8499 | Nominalists cannot translate 'red resembles pink more than blue' into particulars [Jackson] |
| Full Idea: It is not always possible for nominalists to translate all statements putatively about universals as statements about particulars. It is not possible for 'red is a colour' and 'red resembles pink more than blue' | |
| From: Frank Jackson (Statements about Universals [1977], p.89) | |
| A reaction: His second example strikes me as the biggest challenge facing nominalism. I wish they wouldn't use secondary qualities as examples. I am unconvinced that the existence of universals will improve the explanation. It's a mystery. |
| 8500 | Colour resemblance isn't just resemblance between things; 'colour' must be mentioned [Jackson] |
| Full Idea: Some red things resemble some blue things more than some pink things because of factors other than colour. Nominalists must offer 'anything red colour-resembles anything pink', but that may contain a universal in disguise. | |
| From: Frank Jackson (Statements about Universals [1977], p.90) | |
| A reaction: Hume and Quine are probably right that we spot resemblances instantly, and only articulate the respect of the resemblance at a later stage. |
| 13858 | The truth-functional account of conditionals is right, if the antecedent is really acceptable [Jackson, by Edgington] |
| Full Idea: Jackson defends the truth-functional account by saying that for a conditional to be assertable, it must not only be believed that its truth-conditions are satisfied, but the belief must be robust or resilient with respect to the antecedent. | |
| From: report of Frank Jackson (Conditionals and Possibilia [1981]) by Dorothy Edgington - Do Conditionals Have Truth Conditions? 4 | |
| A reaction: ..That is, one would not abandon the conditional if one believed the antecedent to be true. |