| 11034 | The differentiae of genera which are different are themselves different in kind [Aristotle] |
| Full Idea: The differentiae of genera which are different and not subordinate one to the other are themselves different in kind. | |
| From: Aristotle (Categories [c.331 BCE], 01b16) | |
| A reaction: This seems to be indicating a category mistake, as he warns us not to attribute the wrong kind of differentiae to something we are picking out. |
| 12491 | Asking whether man's will is free is liking asking if sleep is fast or virtue is square [Locke] |
| Full Idea: To ask whether man's will be free is as improper as to ask whether sleep be swift, or virtue square. | |
| From: John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.21.14) | |
| A reaction: Beautiful illustrations of category mistakes, long before the actual phrase was coined. |
| 8632 | You can't transfer external properties unchanged to apply to ideas [Frege] |
| Full Idea: It would be remarkable if a property abstracted from external things could be transferred without any change of sense to events, to ideas and to concepts, like speaking of 'blue ideas' or 'salty concepts'. | |
| From: Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], §24) | |
| A reaction: Since those phrases make perfectly good metaphorical sense, I presume the Frege was a fairly literal sort of chap. Is this the earliest emergence of the idea of a category mistake? |
| 8468 | The sentence 'procrastination drinks quadruplicity' is meaningless, rather than false [Russell, by Orenstein] |
| Full Idea: Russell proposed (in his theory of types) that sentences like 'The number two is fond of cream cheese' or 'Procrastination drinks quadruplicity' should be regarded as not false but meaningless. | |
| From: report of Bertrand Russell (Introduction to Mathematical Philosophy [1919]) by Alex Orenstein - W.V. Quine Ch.3 | |
| A reaction: This seems to be the origin of the notion of a 'category mistake', which Ryle made famous. The problem is always poetry, where abstractions can be reified, or personified, and meaning can be squeezed out of almost anything. |
| 6437 | The theory of types makes 'Socrates and killing are two' illegitimate [Russell] |
| Full Idea: 'Socrates and killing are two' would be an illegitimate sentence according to the doctrine of types. | |
| From: Bertrand Russell (My Philosophical Development [1959], Ch.14) | |
| A reaction: This nicely shows how Ryle's notion of a 'category mistake', although it is a commonsense observation of bogus reasoning, arises out of Russell's logical analysis of sets. Of course, the theory of types has its critics. |
| 18002 | As well as a truth value, propositions have a range of significance for their variables [Russell] |
| Full Idea: Every proposition function …has, in addition to its range of truth, a range of significance, i.e. a range within which x must lie if φ(x) is to be a proposition at all, whether true or false. This is the first point of the theory of types. | |
| From: Bertrand Russell (The Principles of Mathematics [1903], App B:523), quoted by Ofra Magidor - Category Mistakes 1.2 | |
| A reaction: Magidor quotes this as the origin of the idea of a 'category mistake'. It is the basis of the formal theory of types, but is highly influential in philosophy generally, especially as a criterion for ruling many propositions as 'meaningless'. |
| 21561 | 'The number one is bald' or 'the number one is fond of cream cheese' are meaningless [Russell] |
| Full Idea: 'The number one is bald' or 'the number one is fond of cream cheese' are, I maintain, not merely silly remarks, but totally devoid of meaning. | |
| From: Bertrand Russell (Substitutional Classes and Relations [1906], p.166) | |
| A reaction: He connects this to paradoxes in set theory, such as the assertion that 'the class of human beings is a human being' (which is the fallacy of composition). |
| 18706 | Words of the same kind can be substituted in a proposition without producing nonsense [Wittgenstein] |
| Full Idea: 'Blue' and 'brown' are of the same kind, for the substitution of one for the other, though it may falsify the proposition, does not make nonsense of it. | |
| From: Ludwig Wittgenstein (Lectures 1930-32 (student notes) [1931], A I.4) | |
| A reaction: He chooses an easy example, because they are determinates of the determinable 'coloured'. What if I say 'the sky is blue', and then substitute 'frightening' for 'blue'? |
| 18004 | We can't do philosophy without knowledge of types and categories [Ryle] |
| Full Idea: We are in the dark about the nature of philosophical problems and methods if we are in the dark about types and categories. | |
| From: Gilbert Ryle (Categories [1938], p.189), quoted by Ofra Magidor - Category Mistakes 1.2 | |
| A reaction: Magidor and others take this to be an assertion about language and logic, but I take it to be an assertion about reality. It is an early assertion of Schaffer's claim that ontology concerns the structure of existence, and not just what exists. |
| 17998 | Category mistakes are either syntactic, semantic, or pragmatic [Magidor] |
| Full Idea: A plausible case can be made for explaining the phenomenon of category mistakes in terms of each of syntax, semantics, and pragmatics. | |
| From: Ofra Magidor (Category Mistakes [2013], 1.1) | |
| A reaction: I want to explain them in terms of (structured) ontology, but she totally rejects that on p.156. Her preferred account is that they are presupposition failures, which is pragmatics. She splits the semantic view into truth-valued and non-truth-valued. |
| 18019 | People have dreams which involve category mistakes [Magidor] |
| Full Idea: It is an empirical fact that people often sincerely report having had dreams which involve category mistakes. | |
| From: Ofra Magidor (Category Mistakes [2013], 3.4) | |
| A reaction: She doesn't give any examples, but I was thinking that this might be the case before I read this idea. Dreams seem to allow you to live with gaps in reality that we don't tolerate when awake. |