Morning Star and Evening Star

London Ed of Beyond Necessity does a good job patiently explaining the 'morning star' - 'evening star' example to one of his uncomprehending readers.  But I don't think Ed gets it exactly right.  I quibble with the following:

Summarising:
(1) The sentence “the morning star is the evening star” has informational content.
(2) The sentence “the morning star is the morning star” does not have informational content.
(3) Therefore, the term “the morning star” does not have the same informational content as “the evening star”.

One quibble is this.  Granted, the two sentences differ in cognitive value, Erkenntniswert.  (See "On Sense and Reference" first paragraph.) The one sentence expresses a truth of logic, and thus a truth knowable a priori.  The other sentence expresses a factual truth of astronomy, one knowable only a posteriori.  But note  that Frege says that they differ in cognitive value, not that the one has it while the other doesn't.  Ed says that the one has it while the other doesn't -- assuming Ed is using 'informational content' to translate Erkenntniswert.  There is some annoying slippage here.

More importantly, I don't see how cognitive value/informational content can be had by such subsentential items as 'morning star' and 'evening star.'  Thus I question the validity of the inference from (1) & (2) to (3). Neither term gives us any information.  So it cannot be that they differ in the information they give.  Nor can they be contrasted in point of giving or not giving information.  Information is conveyable only by sentences or propositions.

I say this:  neither of the names Morgenstern (Phosphorus) or Abendstern (Hesperus) have cognitive value or informational content.  (The same holds, I think, if they are not proper names but definite descriptions.)  Only indicative sentences (Saetze) and the propositions (Gedanken) they express have such value or content.  As I see it, for Frege, names have sense (Sinn) and reference (Bedeutung), and they may conjure up  subjective ideas (Vorstellungen) in the minds of their  users.  But no name has cognitive value.  Sentences and propositions, however, have sense, reference, and cognitive value.  Interestingly, concept-words (Begriffswoerter)  or predicates also have sense and reference, but no cognitive value.

I also think Ed misrepresents the Compositionality Principle.  Frege is committed to compositionality of sense (Sinn),  not compositionality of informational content/cognitive value.  So adding the C. P. to his premise set will not validate the  above inference.

Comments

[Edward Ockham]

That’s an interesting point. Is it that only a whole proposition can give us information, hence have informational content? I am trying to explain the morning star argument to a chap who is very clever and has a background in the ‘hard sciences’, but who sees philosophy as a wishy-washy subject without any intellectual rigour - metaphysica sunt, non leguntur - so I thought using the idea of ‘information’, which scientists find useful and intelligible, would help.

However, having defined ‘morning star’ by the description ‘heavenly body that appears in the morning before sunrise and which closely follows the motion of the sun’ etc, do you agree that ‘there is such an object as the morning star’ contains information? I.e. even if a description contains no information, we can readily associate it with an existential statement which does contain information. Then we could probably rewrite my argument to you satisfaction, though I haven't tried.

[Bill Vallicella]

Yes, I agree that the existential sentence contains information. But the definite description by itself does not.

The underlying problem, of course, is: How are true informative identity sentences possible? If the sentence has the form *a = a* then it is true but uninformative (or perhaps only trivially informative), while if it has the form *a = b* then it is bristling wiht non-logicval content and highly informative but false. F. solves the problem by distinguishing sense and reference. And then he applies the diostinction to names, concept-words and whole sentences, with esults that are very interesting if slightly bizarre. Thus all true indicative sentences refer to das Wahre, and all false ones to das Falsche.

I must praise you for your patience with your benighted commenter. Too many of these science types display the arrogance of ignorance. Without any study at all of serious philosophy, they think they have the right to shoot their mouths off about it and pronounce it 'wishy-washy' and worse. We however know not to gas off about subjects with which we are not familiar.

[Edward Ockham]

1. A further thought. Perhaps we can say that terms have informational content, at least in the context of a proposition (decl. sentence). We agree the proposition "grass is green" has informational content. This content differs from the content of "grass is yellow". How? How does changing the word 'green' to the word 'yellow' change the informational content of the whole proposition? Surely (!) because the informational value of the word 'green' is different from the informational value of the word 'yellow'. Thus the informational value of a term is precisely its contribution to the informational value of the whole sentence. Frege says somewhere (in his letter to Jourdain i think) that the same sense corresponds to the same word, and that is why language is useful. We could use a single sign for the whole proposition, as with a train signal (red = the track is closed, green = the track is clear), but he says that would not be very helpful, as we would have to devise a new sign for every different thought we wanted to express. So we split the thought up into parts. If we understand 'informational value' in this way - as the contribution to the informational value of the whole proposition, my argument is sound, I think.

2. Off topic, but what are the advantages of Typepad, apart from not being Blogger? As you see from my blog, it is unusable because of an upgrade they made. Looks like all versions of Internet Explorer are affected. I think you recommend Typepad, no?