[2.5.4.] Further Points About Sense and Reference.
Senses are not mental. They are not psychological items in anyone’s mind. Rather, they are public and external to the mind. A sense “may be a common property of many and therefore is not a part or a mode of the individual mind.” (11)
In particular, senses are not the same as ideas. Frege distinguishes senses, which are non-mental, from ideas, which he takes to be the “internal images” a person associates with expressions, e.g., the mental image I have of Barack Obama. My idea of Barack Obama must be different (that is, not numerically identical) than yours, since mine is in my mind and yours is in your mind. But you and I may both “grasp” the same sense of the name “Barack Obama.” Says Frege, two individuals “are not prevented from grasping the same sense; but they cannot have the same idea.” (11)
· Frege uses the following telescope analogy to help explain the differences among ideas, senses and references:
Somebody observes the moon through a telescope. I compare the Moon itself to the reference; it is the object of the observation, mediated by the real image projected by the object glass in the interior of the telescope, and by the retinal image of the observer. The former I compare to the sense, the latter is like the idea or experience. The optical image in the telescope is indeed one-sided and dependent upon the standpoint of observation; but it is still objective, inasmuch as it can be used by several observers. At any rate it could be arranged for several to use it simultaneously. But each one would have his own retinal image. On account of the diverse shapes of the observers’ eyes, even a geometrical congruence could hardly be achieved, and an actual coincidence would be out of the question. This analogy might be developed still further, by assuming A’s retinal image made visible to B; or A might also see his own retinal image in a mirror. In this way we might perhaps show how an idea can itself be taken as an object, but as such is not for the observer what it directly is for the person having the idea. (11)
Reference depends on sense. In other words, the reference of an expression (if in fact it has a reference) depends on the sense of the expression; e.g.,
· it is because the sense of the name “Barack Obama” is what it is that that name refers to Obama and not anyone else;
· it is because the sense of “Santa Claus” is what it is (something like “The magical, jolly, rotund man who lives at the North Pole and delivers toys all over the world on Christmas Eve”) that the expression “Santa Claus” does not refer to anything at all.
And as that last example illustrates…
All meaningful expressions have a sense, but they don’t all have a reference:
It may perhaps be granted that every grammatically well-formed expression representing a proper name always has a sense. But this is not to say that to the sense there also corresponds a reference. The words “the celestial body most distant from the Earth” have a sense, but it is very doubtful if they also have a reference. (10)
For example, “Santa Claus” has a sense but no reference (since there is no real thing that that definite description describes).
[2.6.] The Sense and Reference of a Sentence.
Up to now Frege has limited his discussion of sense and reference to expressions that refer to single definite individuals, especially ordinary proper names, e.g., “Barack Obama” and “the Morning Star.”
But he believes that the sense/reference distinction can be applied to declarative sentences, as well.
What is the sense of a declarative sentence?
The sense of a given declarative sentence is “the thought” expressed by it.
What does Frege mean by “thought”?:
So far we have considered the sense and reference only of such expressions, words, or signs as we have called proper names. We now inquire concerning the sense and reference for an entire declarative sentence. Such a sentence contains a thought. (12)
By a thought I understand not the subjective performance of thinking but its objective content, which is capable of being the common property of several thinkers. (20 n.5, emphasis added)
So according to Frege, the thought expressed by a sentence is not mental or subjective, but public, just like the sense of a name.
He seems to mean by “thought” what contemporary philosophers call a proposition:
proposition (df.): what a set of synonymous declarative sentences have in common; e.g., the declarative sentences “Snow is white,” “La nieve es blanca,” and “Schnee ist weiss” have in common the proposition that snow is white.
So for Frege, the sense of the declarative sentence “Odysseus was set ashore at Ithaca while sound asleep” is the proposition that Odysseus was set ashore at Ithaca while sound asleep.
What is the reference of a declarative sentence?
We are … driven into accepting the truth value of a sentence as constituting its reference. By the truth value of a sentence I understand the circumstance that it is true or false. There are no further truth values. For brevity I call the one the True, the other the False. (12)
The reference of all true sentences is the same: it is the True.
Likewise, the reference of all false sentences is the same: it is the False.
But some declarative sentences have no reference. They are neither true nor false, and refer neither to the True nor to the False.
E.g., “Odysseus was set ashore at Ithaca while sound asleep.”
This sentence has a sense, namely, the proposition that Odysseus was set ashore at Ithaca while he was sleeping.
But the name “Odysseus” has no reference; i.e., there is no such person as Odysseus. Because of the sense expressed by this name (which is something like: the son of Laertes who ruled Ithaca and fought in the Trojan War), the name does not refer to anything.
Frege’s view is that if a sentence contains an expression that has no reference, then the sentence as a whole has no reference.
For Frege, this means that the sentence is neither true nor false.
[As we will soon see, this is a point on which Frege and Bertrand Russell disagree.]
Stopping point for Thursday September 6. For next time, finish reading Frege’s “Thought” (pp.24-34). Your first response paper, on that reading, is due at the beginning of Tuesday’s class. Your grade will be reduced if the response paper is turned in late. Instructions for the response papers are here.
Note: this set of lecture notes includes some of what I emailed to everyone on Tuesday Sept.4. Please DISREGARD those emailed notes and use these instead. The rest of the emailed notes (which also deal with “On Sense and Reference”) will be covered at the beginning of our next class meeting.
 Frege calls all such expressions proper names, even definite descriptions like “the last star seen in the morning.”
 In Frege’s German, the word for thought is “Gedanke.”
 Frege’s argument that the thought expressed by a sentence cannot be its reference: replacing a word in a sentence with a co-referential word cannot change its reference; it can, however, change the thought the sentence contains (since a person could know the sentence before the change to be true while not knowing whether the sentence after the change is true, or vice versa); therefore, the thought contained by a sentence cannot be the sentence’s reference; therefore (assuming that the thought must be either the sentence’s sense or its reference) the thought contained by a sentence must be the sense of the sentence.
This page last updated 9/6/2012.
Copyright © 2012 Robert Lane. All rights reserved.