21 ideas
| 18806 | Frege thought traditional categories had psychological and linguistic impurities [Frege, by Rumfitt] |
| Full Idea: Frege rejected the traditional categories as importing psychological and linguistic impurities into logic. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by Ian Rumfitt - The Boundary Stones of Thought 1.2 | |
| A reaction: Resisting such impurities is the main motivation for making logic entirely symbolic, but it doesn't follow that the traditional categories have to be dropped. |
| 8490 | First-level functions have objects as arguments; second-level functions take functions as arguments [Frege] |
| Full Idea: Just as functions are fundamentally different from objects, so also functions whose arguments are and must be functions are fundamentally different from functions whose arguments are objects. The latter are first-level, the former second-level, functions. | |
| From: Gottlob Frege (Function and Concept [1891], p.38) | |
| A reaction: In 1884 he called it 'second-order'. This is the standard distinction between first- and second-order logic. The first quantifies over objects, the second over intensional entities such as properties and propositions. |
| 8492 | Relations are functions with two arguments [Frege] |
| Full Idea: Functions of one argument are concepts; functions of two arguments are relations. | |
| From: Gottlob Frege (Function and Concept [1891], p.39) | |
| A reaction: Nowadays we would say 'two or more'. Another interesting move in the aim of analytic philosophy to reduce the puzzling features of the world to mathematical logic. There is, of course, rather more to some relations than being two-argument functions. |
| 8487 | Arithmetic is a development of logic, so arithmetical symbolism must expand into logical symbolism [Frege] |
| Full Idea: I am of the opinion that arithmetic is a further development of logic, which leads to the requirement that the symbolic language of arithmetic must be expanded into a logical symbolism. | |
| From: Gottlob Frege (Function and Concept [1891], p.30) | |
| A reaction: This may the the one key idea at the heart of modern analytic philosophy (even though logicism may be a total mistake!). Logic and arithmetical foundations become the master of ontology, instead of the servant. The jury is out on the whole enterprise. |
| 18899 | Frege takes the existence of horses to be part of their concept [Frege, by Sommers] |
| Full Idea: Frege regarded the existence of horses as a property of the concept 'horse'. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by Fred Sommers - Intellectual Autobiography 'Realism' |
| 4028 | Frege allows either too few properties (as extensions) or too many (as predicates) [Mellor/Oliver on Frege] |
| Full Idea: Frege's theory of properties (which he calls 'concepts') yields too few properties, by identifying coextensive properties, and also too many, by letting every predicate express a property. | |
| From: comment on Gottlob Frege (Function and Concept [1891]) by DH Mellor / A Oliver - Introduction to 'Properties' §2 | |
| A reaction: Seems right; one extension may have two properties (have heart/kidneys), two predicates might express the same property. 'Cutting nature at the joints' covers properties as well as objects. |
| 8489 | The concept 'object' is too simple for analysis; unlike a function, it is an expression with no empty place [Frege] |
| Full Idea: I regard a regular definition of 'object' as impossible, since it is too simple to admit of logical analysis. Briefly: an object is anything that is not a function, so that an expression for it does not contain any empty place. | |
| From: Gottlob Frege (Function and Concept [1891], p.32) | |
| A reaction: Here is the core of the programme for deriving our ontology from our logic and language, followed through by Russell and Quine. Once we extend objects beyond the physical, it becomes incredibly hard to individuate them. |
| 8361 | What is true used to be possible, but it may no longer be so [Wright,GHv] |
| Full Idea: It is not very natural to say of that which is true that it is also possible. ...What is true was possible - but whether it still is a potency of the world is not certain. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §5) | |
| A reaction: A simple and rather important distinction. Before encountering this, I would certainly have been happy to affirm that the actual is possible, but actually it may not be. The power to create differs from the power to sustain. Could God re-create the world? |
| 8875 | Sense experiences must have conceptual content, since they are possible reasons for judgements [Brewer,B] |
| Full Idea: Given that sense experiential states do provide reasons for empirical beliefs, they must have conceptual content, ...where a mental state with conceptual content is one where the content is of a possible judgement by the subject. | |
| From: Bill Brewer (Perceptual experience has conceptual content [2005], I) | |
| A reaction: This is, I believe, wrong. Even complex observations, like a pool of blood, only become reasons when they have been interpreted. Otherwise they are just the raw ingredients of evidence. How could an uninterpreted red patch be a 'reason'? |
| 9947 | Concepts are the ontological counterparts of predicative expressions [Frege, by George/Velleman] |
| Full Idea: Concepts, for Frege, are the ontological counterparts of predicative expressions. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2 | |
| A reaction: That sounds awfully like what many philosophers call 'universals'. Frege, as a platonist (at least about numbers), I would take to be in sympathy with that. At least we can say that concepts seem to be properties. |
| 10319 | An assertion about the concept 'horse' must indirectly speak of an object [Frege, by Hale] |
| Full Idea: Frege had a notorious difficulty over the concept 'horse', when he suggests that if we wish to assert something about a concept, we are obliged to proceed indirectly by speaking of an object that represents it. | |
| From: report of Gottlob Frege (Function and Concept [1891], Ch.2.II) by Bob Hale - Abstract Objects | |
| A reaction: This sounds like the thin end of a wedge. The great champion of objects is forced to accept them here as a façon de parler, when elsewhere they have ontological status. |
| 8488 | A concept is a function whose value is always a truth-value [Frege] |
| Full Idea: A concept in logic is closely connected with what we call a function. Indeed, we may say at once: a concept is a function whose value is always a truth-value. ..I give the name 'function' to what is meant by the 'unsaturated' part. | |
| From: Gottlob Frege (Function and Concept [1891], p.30) | |
| A reaction: So a function becomes a concept when the variable takes a value. Problems arise when the value is vague, or the truth-value is indeterminable. |
| 9948 | Unlike objects, concepts are inherently incomplete [Frege, by George/Velleman] |
| Full Idea: For Frege, concepts differ from objects in being inherently incomplete in nature. | |
| From: report of Gottlob Frege (Function and Concept [1891]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.2 | |
| A reaction: This is because they are 'unsaturated', needing a quantified variable to complete the sentence. This could be a pointer towards Quine's view of properties, as simply an intrinsic feature of predication about objects, with no separate identity. |
| 4972 | I may regard a thought about Phosphorus as true, and the same thought about Hesperus as false [Frege] |
| Full Idea: From sameness of meaning there does not follow sameness of thought expressed. A fact about the Morning Star may express something different from a fact about the Evening Star, as someone may regard one as true and the other false. | |
| From: Gottlob Frege (Function and Concept [1891], p.14) | |
| A reaction: This all gets clearer if we distinguish internalist and externalist theories of content. Why take sides on this? Why not just ask 'what is in the speaker's head?', 'what does the sentence mean in the community?', and 'what is the corresponding situation?' |
| 8363 | p is a cause and q an effect (not vice versa) if manipulations of p change q [Wright,GHv] |
| Full Idea: What makes p a cause-factor relative to the effect-factor q (rather than vice versa) is the fact that by manipulating p, producing changes in it 'at will', we could bring about changes in q. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §8) | |
| A reaction: As a solution to the direction-of-causation problem, I suspect that this proposal is begging the question. Will a causal explanation be offered of the action of manipulation? If he mistook his manipulation for a cause when it is actually an effect... |
| 8364 | We can imagine controlling floods by controlling rain, but not vice versa [Wright,GHv] |
| Full Idea: Given our present knowledge of the laws of nature, we can imagine ways of controlling floods by controlling rainfall, but not the other way round. That is should be so, however, is contingent. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §8) | |
| A reaction: Despite my objections to Idea 8363, this is a good example. It won't establish the metaphysics of the direction of causation, though, because God might control rainfall by controlling floods. Maybe causation is more like a motorway pile-up than dominoes. |
| 8366 | The very notion of a cause depends on agency and action [Wright,GHv] |
| Full Idea: There is an implicit dependence of the very notion of a cause on a concept of agency and action. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §10) | |
| A reaction: This is because he thinks experimental intervention is the key to the concept of causation (see Ideas 8362 and 8363). Others go further, and say that the concept of causation arises from subjective experience of performing actions. I quite like that. |
| 8362 | We give regularities a causal character by subjecting them to experiment [Wright,GHv] |
| Full Idea: What confers on observed regularities the character of causal or nomic connections is the possibility of subjecting cause-factors to experimental test by interfering with the 'natural' course of events. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §7) | |
| A reaction: This is von Wright's distinctive proposal, making causation a feature of the culture of science, rather than of ordinary life. But see Idea 2461. Causation is becoming too epistemological for my taste. Either it is a feature of reality, or forget it. |
| 8360 | We must further analyse conditions for causation, into quantifiers or modal concepts [Wright,GHv] |
| Full Idea: We may be able to analyse causation into conditionship relations between events or states of affairs, ...but conditions cannot be regarded as logical primitives, ... and must be analysed into quantifiers, or modal concepts. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §2) | |
| A reaction: [very compressed] A nice illustration of the aim of analytical philosophy - to analyse the elements of reality down to logical primitives. This is the dream of Descartes and Leibniz, continued by Russell and co. Do we still have this aspiration? |
| 8365 | Some laws are causal (Ohm's Law), but others are conceptual principles (conservation of energy) [Wright,GHv] |
| Full Idea: Not all laws are causal 'experimentalist' laws, such as those for falling bodies, or the Gas Law, or Ohm's Law. Some are more like conceptual principles, giving a frame of reference, such as inertia, or conservation of energy, or the law of entropy. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §9) | |
| A reaction: An interesting and important distinction, whenever one is exploring the links between theories of causation and of laws of nature. If one wished to attack the whole concept of 'laws of nature', this might be a good place to start. |
| 8491 | The Ontological Argument fallaciously treats existence as a first-level concept [Frege] |
| Full Idea: The ontological proof of God's existence suffers from the fallacy of treating existence as a first-level concept. | |
| From: Gottlob Frege (Function and Concept [1891], p.38 n) | |
| A reaction: [See Idea 8490 for first- and second-order functions] This is usually summarised as the idea that existence is a quantifier rather than a predicate. |