Combining Philosophers

Ideas for Hermarchus, Gottlob Frege and Georg Kreisel

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15 ideas

18. Thought / D. Concepts / 1. Concepts / a. Nature of concepts
Early Frege takes the extensions of concepts for granted [Frege, by Dummett]
     Full Idea: In the 'Grundlagen' Frege takes the notion of the extension of a concept for granted as unproblematic.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Michael Dummett - Frege philosophy of mathematics Ch.16
     A reaction: This comfortable notion was undermined by Russell's discovery of a concept which couldn't have an extension. Maybe we could defeat the Russell problem (and return to Frege's common sense) by denying that sets are objects.
18. Thought / D. Concepts / 3. Ontology of Concepts / c. Fregean concepts
Concepts are, precisely, the references of predicates [Frege, by Wright,C]
     Full Idea: For Frege concepts are, precisely, the Bedeutungen of predicates.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Crispin Wright - Frege's Concept of Numbers as Objects 1.iv
     A reaction: On p.17 Wright challenges Frege's right to make that assumption.
A concept is a non-psychological one-place function asserting something of an object [Frege, by Weiner]
     Full Idea: A concept is a one-place function - something that can be asserted of an object - as found in 'Earth is a planet' and 'Venus is a planet'. This notion of concept does not belong to psychology at all.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Joan Weiner - Frege Ch.4
     A reaction: This doesn't seem to leave room for the concept of the object or substance of which the something is asserted. In 'x is a planet' we need a concept of what x is. But then Frege will reduce the reference to a set of descriptions (i.e. functions).
Fregean concepts have precise boundaries and universal applicability [Frege, by Koslicki]
     Full Idea: Both precise boundaries and universal applicability are built into the very notion of a Fregean concept from the outset, while isolation and non-arbitrary division are additional criteria imposed on concepts.
     From: report of Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884]) by Kathrin Koslicki - Isolation and Non-arbitrary Division 2.1
     A reaction: The latter two criteria are for concepts which create counting units.
Psychological accounts of concepts are subjective, and ultimately destroy truth [Frege]
     Full Idea: Defining concepts psychologically, in terms of the nature of the human mind, makes everything subjective, and if we follow it through to the end, does away with truth.
     From: Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], Intro)
     A reaction: This is the reason for Frege's passionate opposition to psychological approaches to thought. The problem, though, is to give an account in which the fixity of truth connects to the fluctuations of mental life. How does it do that??
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.
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.
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.
'The concept "horse"' denotes a concept, yet seems also to denote an object [Frege, by McGee]
     Full Idea: The phrase 'the concept "horse"' can be the subject of a sentence, and ought to denote an object. But it clearly denotes the concept "horse". Yet Fregean concepts are said to be 'incomplete' objects, which led to confusion.
     From: report of Gottlob Frege (On Sense and Reference [1892]) by Vann McGee - Logical Consequence 4
     A reaction: This is the notorious 'concept "horse"' problem, which was bad news for Frege's idea of a concept.
Frege equated the concepts under which an object falls with its properties [Frege, by Dummett]
     Full Idea: Frege equated the concepts under which an object falls with its properties.
     From: report of Gottlob Frege (On Concept and Object [1892], p.201) by Michael Dummett - Frege philosophy of mathematics Ch.8
     A reaction: I take this to be false, as objects can fall under far more concepts than they have properties. I don't even think 'being a pencil' is a property of pencils, never mind 'being my favourite pencil', or 'not being Alexander the Great'.
A concept is a function mapping objects onto truth-values, if they fall under the concept [Frege, by Dummett]
     Full Idea: In later Frege, a concept could be taken as a particular case of a function, mapping every object on to one of the truth-values (T or F), according as to whether, as we should ordinarily say, that object fell under the concept or not.
     From: report of Gottlob Frege (Grundgesetze der Arithmetik 1 (Basic Laws) [1893]) by Michael Dummett - The Philosophy of Mathematics 3.5
     A reaction: As so often in these attempts at explanation, this sounds circular. You can't decide whether an object truly falls under a concept, if you haven't already got the concept. His troubles all arise (I say) because he scorns abstractionist accounts.
Frege took the study of concepts to be part of logic [Frege, by Shapiro]
     Full Idea: Frege took the study of concepts and their extensions to be within logic.
     From: report of Gottlob Frege (Grundgesetze der Arithmetik 1 (Basic Laws) [1893]) by Stewart Shapiro - Foundations without Foundationalism 7.1
     A reaction: This is part of the plan to make logic a universal language (see Idea 13664). I disagree with this, and with the general logicist view of the position of logic. The logical approach thins concepts out. See Deleuze/Guattari's horror at this.
18. Thought / D. Concepts / 4. Structure of Concepts / a. Conceptual structure
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.
18. Thought / D. Concepts / 5. Concepts and Language / b. Concepts are linguistic
A concept is a possible predicate of a singular judgement [Frege]
     Full Idea: A concept is for me that which can be predicate of a singular judgement-content.
     From: Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], §66 n)
     A reaction: This seems intuitively odd, given that a predicate could (in principle) be of almost infinite complexity, whereas I would be reluctant to call anything a 'concept' if it couldn't be grasped by a single action of a normal conscious mind.
As I understand it, a concept is the meaning of a grammatical predicate [Frege]
     Full Idea: As I understand it, a concept is the meaning of a grammatical predicate.
     From: Gottlob Frege (On Concept and Object [1892], p.193)
     A reaction: All the ills of twentieth century philosophy reside here, because it makes a concept an entirely linguistic thing, so that animals can't have concepts, and language is cut off from reality, leading to relativism, pragmatism, and other nonsense.