Why are imperatives not propositions according to Frege?

Question

I'm reading Frege's "On Sense and Nominatum" and I am confused with:

"Imperatives have no nominata; they have only sense. It is true, commands or requests are not propositions, but they are of the same type of propositions. Therefore the words in the dependent clauses after 'to command', 'to request', etc. have indirect nominata. The nominatum of such sentence is thus not a truth-value but a command, a request, and the like."

Why is he saying that "Imperatives have no nominata" and then he is saying that "The nominatum of such sentence is thus not a truth-value but a command, a request, and the like"?

Why is he saying also that "It is true, commands or requests are not propositions, but they are of the same type of propositions."? I do not understand why they wouldn't be a proposition.

Thanks.

Answer 1

In Frege's universe there are two objects corresponding to truth values: the TRUE and the FALSE.

According to Frege's semantics every expression has a sense: for a sentence a thought, and a reference: for a sentence one of the only two truth values.

An imperative has no truth value and thus, according to Frege, it has no reference.

We can compare it to assertions:

Frege held that an assertion is an outward sign of a judgment. A judgment in turn, in Frege's view, is a step from a Thought, that is, a representational content, to the acknowledgment of its truth. Since for Frege, the truth value is the Reference (Bedeutung) of a sentence, a judgment is an advance from Sense to Reference.

See : Mark Textor, Routledge Philosophy GuideBook to Frege on Sense and Reference (2010), page 189:

Frege will work in Sense and Reference through further exceptions from the thesis that an assertoric sentence is a truth-value name. [...] He takes his discussion to show that abstract noun-clauses (that-clauses) are noun phrases that refer to thoughts in certain contexts. [...] Whether an expression is a name of a thought is not syntactically marked; we often have to guess.

[...] not every sentence is an assertoric sentence. When Cato the Elder said ‘Destroy Carthago!’ he did not make an assertion, but gave an order. The sense of an imperative sentence is not a thought.

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You can see also Imperative logic:

Imperative logic is the field of logic concerned with arguments containing sentences in the imperative mood. In contrast to sentences in the declarative mood, imperatives are neither true nor false.

Answer 2

The German word 'Bedeutung', or its Latin translation 'nominatum', from the point of view of an English speaker, means different things when applied to sentences and their parts.

Sentences have Boolean nominata, but the parts within them have nominata of other kinds. "Caesar conquered Gaul" as a whole sentence is either true or false, 'Caesar' and 'Gaul' aren't, they are a person and a region (these are their non-Boolean nominata). So there is a sense in which the sentence 'has' those internal nominata -- it contains references to them -- but the sentence only has the final Boolean nominatum. The language here translates that badly.

"Pick that up!" means something like "It would please me if you were to pick that up." (We sometimes get around to injecting all the parts, just out of order: "Pick that up for me, please; if you would.")

The subject, and an entire subjugating emotional state that I am trying to foist upon you, the heart of the sentence, are missing. The referent of the part you actually say is the action, not the sentence, and it can be neither true nor false without all the other stuff being indirectly added in your mind.

"It would please me if you were to pick that up." is either true or false, but "Pick that up!" is not, it is a reference to an action about which I am wishing.

Answer 3

Frege was concerned with the truth of mathematical statements. In his philosophy of language, the reference of a true sentence is its truth value. Imperatives do not intend to describe things such as they are, as assertive sentences do. They have a pragmatic function which does not relate to Frege's semantic considerations on meaning and truth.

It is also worthy to point out that an imperative is inherently indexical, so its sense does not determine a reference out of context. One could answer that "Please, Robert, close the door." should be equivalent with "Robert closing the door", but that is to misunderstand the purpose of the imperative, since its realization does not intend to assert a fact, but to ask.

Also sentences with indexical elements are not, such as Frege's thoughts, independent of any context, which are objectively real (a common treasure, as described on sense and reference), objective and which determine references.