I am confused about "concept", "sense" and "properties" which may have some similarity but fundamentally are different.

I explain my understanding as follows :

  1. Object-Subject : Frege argued that "thought" is composed of object and concept which can be expressed linguistically by subjects and predicates. Objects and concepts are objective and mind independent in Frege's point of view. For example : "bob is beautiful", bob is the object and ...is beautiful is the concept.

  2. Particulars-Universals : It is claimed by realists that for any (or most) property there is an universal which particulars(if there are some particular) are exemplified by that universal. I n this case, we also have subject-predicates view in the language. particulars are descried by subjects and universals are expressed by predicates. For example, in the above example, bob is a particular and beauty is an universal.

  3. Sense : According to Wikipedia, sense is the "mode of presentation" of the proper names. For example: the sense of Hesperus is the evening star which is a definite description and can be described by predicates in language.

From subject-predicate view, these concepts are very similar. Is there an isomorphism between these different type of concepts?Universals=Concepts=Senses, if we have a concept, do we have a corresponding universal and sense of something? and the difference is that we just use these words in different situations (universals in metaphysics, concept and senses in philosophy of language)?

  • Yes similar... but with specific differences that must be understood through detailed study of original texts and reference literature. A concept in Frege's sense is something "general" that can be "predicated" of one or more individual objects, and thus it is similar to an universal. But there are also second-level concepts predicated of first-level ones, and this is again similar to universal: dog-animal-living thing. Commented Jun 22, 2022 at 14:57
  • Thanks, Would you introduce some references for comparing these ideas? All of literatures which I found discuss on these concepts separately.
    – reza-ebadi
    Commented Jun 22, 2022 at 20:47
  • 1
    Ignacio Angelelli, Studies on Gottlob Frege and Traditional Philosophy (Springer, 1967) Commented Jun 23, 2022 at 6:30

1 Answer 1


A sense is a property of phrases, it is what you mean by a phrase (but not what you refer to or denote). The word "Hesperus" has a sense; the sense is a particular mode in which Venus is observed. Using this language we say that the sense of "Hesperus" is the brightest star in the early evening at certain times, while the denotation of "Hesperus" (what you refer to when you say "Hesperus") is the planet Venus. The sense is a mental object, the denotation is a physical object.

The sense of "Hesperus" is a concept. It is the concept of the brightest star in the early evening at certain times. We can use square brackets to semi-quote a phrase in order to indicate that we mean the concept, so

Sense("Hesperus") = [the brightest star in the early evening at certain times]

In other words, a sense is a concept, but the words "sense" and "concept" are used differently. Typically you talk about the sense of a word or phrase, but you talk about a concept independently of any words. Sense is about language, concept is post-language, you are not longer considering how the concept is expressed.

Another important word here is "extension" which is to "concept" roughly what "denotation" is to "sense". For example, the sense of "Hesperus" is the concept [the brightest star in the early evening at certain times], but the denotation of "Hesperus" is the planet Venus. The extension of the concept [the brightest star in the early evening at certain times] is also the planet Venus. The extension of a concept is the collection of things that fall under that concept.

So, the difference between sense and concept is largely a matter of how the words are used. By contrast, the difference between concept and universal is metaphysical; it has to do with what sorts of things exist.

Let's consider the concept [blue]. Anything blue falls under this concept; that is, the extension of the concept [blue] is the set of all blue things. The concept [blue] is accessible only to the mind. Although there may be something out there in the world that all blue things have in common, this is not assumed when we talk about the concept [blue]. We are just talking about things that have a certain sense impression on typical human vision.

By contrast, the universal, blueness, is something that exists out there in the world. It may or may not be physical, but the point is that blueness is something that blue objects have and non-blue objects don't have. It is part of the objective, mind-independent description of the universe. In fact, it is not only part of the description of the universe, but a causally significant part of the universe; for example, a rabbit has long ears and is able to hop specifically because it partakes of the universal, rabbitness. This is a metaphysical assumption made by the theory of universals, but but not made by concept theories.

There is also a debate over whether purely abstract objects exist (and concepts are purely abstract objects), but this is a different metaphysical debate. Universals are not purely abstract objects.

  • Thank you so much for your answer, I thought that concepts were objective and mind independent in Frege's view and this was my confusion between concepts and universals. if I understand correctly, propositions are composed of objects and concepts and if propositions are mind-independent, so concepts are also independent but you said that "The concept [blue] is accessible only to the mind"
    – reza-ebadi
    Commented Jun 23, 2022 at 10:15
  • @reza-ebadi, concepts are objective and mind-independent in the sense that the same concept can be entertained by many minds, and that it is independent of any particular mind. Concepts are not mental states like thoughts or feelings, which exist in only one mind and cannot be shared. For example, if you are feeling pain, I can't feel your pain. I might feel a very similar pain, but I would be feeling my pain, and not yours. By contrast, we can both think about the concept [blue] and we are thinking about the same concept. Commented Jun 23, 2022 at 10:21
  • So you mean, concepts are intersubjective rather than objective?
    – reza-ebadi
    Commented Jun 23, 2022 at 10:31
  • 1
    @reza-ebadi, Frege would have said they are objective. Commented Jun 23, 2022 at 12:49

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