6 ideas
| 8964 | Entities can be multiplied either by excessive categories, or excessive entities within a category [Hoffman/Rosenkrantz] |
| Full Idea: There are two ways that entities can be multiplied unnecessarily: by multiplying the number of explanatory categories, and by multiplying the number of entities within a category. | |
| From: J Hoffman/G Rosenkrantz (Platonistic Theories of Universals [2003], 4) | |
| A reaction: An important distinction. The orthodox view is that it is the excess of categories that is to be avoided (e.g. by nominalists). Possible worlds in metaphysics, and multiple worlds in physics, claim not to violate the first case. |
| 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'. |
| 8962 | 'There are shapes which are never exemplified' is the toughest example for nominalists [Hoffman/Rosenkrantz] |
| Full Idea: The example which presents the most serious challenge to nominalism is 'there are shapes which are never exemplified'. | |
| From: J Hoffman/G Rosenkrantz (Platonistic Theories of Universals [2003], 3) | |
| A reaction: To 'exemplify' a shape must it be a physical object, or a drawing of such an object, or a description? If none of those have ever existed, I'm not sure what 'are' is supposed to mean. They seem to be possibilia (with all the associated problems). |
| 8961 | Nominalists are motivated by Ockham's Razor and a distrust of unobservables [Hoffman/Rosenkrantz] |
| Full Idea: The two main motivations for nominalism are an admirable commitment to Ockham's Razor, and a queasiness about postulating entities that are unobservable or non-empirical, existing in a non-physical realm. | |
| From: J Hoffman/G Rosenkrantz (Platonistic Theories of Universals [2003], 3) | |
| A reaction: It doesn't follow that because the entities are unobservable that they are non-physical. Consider the 'interior' of an electron. Neverless I share a love of Ockham's Razor and a deep caution about unobservables. |
| 8963 | Four theories of possible worlds: conceptualist, combinatorial, abstract, or concrete [Hoffman/Rosenkrantz] |
| Full Idea: There are four models of the ontological status of possible worlds: conceptualist (mental constructions), combinatorial (all combinations of the actual world), abstract worlds (conjunction of propositions), and concrete worlds (collections of concreta). | |
| From: J Hoffman/G Rosenkrantz (Platonistic Theories of Universals [2003], 4) | |
| A reaction: [the proponents cited are, in order, Rescher, Cresswell, Plantinga and Lewis] They dismiss Rescher and Cresswell, both of whom seem to me more plausible than Plantinga or Lewis. 'Possible' can't figure in the definition. Possible to us, or in reality? |
| 8433 | There are few traces of an event before it happens, but many afterwards [Lewis, by Horwich] |
| Full Idea: Lewis claims that most events are over-determined by subsequent states of the world, but not by their history. That is, the future of every event contains many independent traces of its occurrence, with little prior indication that it would happen. | |
| From: report of David Lewis (Counterfactual Dependence and Time's Arrow [1979]) by Paul Horwich - Lewis's Programme p.209 | |
| A reaction: Lewis uses this asymmetry to deduce the direction of causation, and hence the direction of time. Most people (including me, I think) would prefer to use the axiomatic direction of time to deduce directions of causation. Lewis was very wicked. |