Thoughts and sense are two technical terms in philosophy. I will describe Frege’s concept of a “thought.” I will then extend that to look at Burge’s comments on sense and meaning.
Frege argues that if I use a designator such as “that lime tree” that I believe refers but does not, I wander into “the realm of fiction.” Frege makes the further claim that the content of sentences containing non-referring terms is not truth-evaluable. But am I really failing to refer?
If I say “lightning struck that tree,” people will look out of the window to see whether this is true. They will see that it is true, and they will come to have knowledge of that fact. They may say that it is regrettable because they enjoyed the shade of `that lime tree’. All of this is the case even if the tree is in fact an oak. So I have had a conversation with someone else. That person has learned a new fact. They have formed an attitude towards that fact, and successfully communicated that attitude to me.
“Thoughts” and Sense: Failure To Refer
Note that even if my interlocutor has failed to refer to a tree, that does not prevent them from referring to their attitude to a tree. Are we then to say that their attitude has no intentional object? All of this suggests that referral has taken place. Moreover, even if the empty terms do enter the realm of fiction, why does that entail that they are not truth-evaluable? The claim `Sherlock Holmes plays the violin badly’ seems to have two truth values; it is true in the context of works by Arthur Conan Doyle and false in the actual world.
Finally, `killer whales’ are in fact not whales but dolphins. Fewer people know that than the number who would be disposed to assent to a number of true statements about killer whales. They can swim, they live in the sea etc.
Will Frege claim that this term does refer because many of us have all agreed together to make this error? But if “killer whales” is a compositional term as opposed to an empty name, and it means “that subset of whales which kill,” then it does not refer. Are stories about killer whales all fictional. So that in the course of an hour-long nature documentary on the topic, no-one says anything and no-one learns anything?
“Thoughts” and Sense: Burge’s ‘Frege on Sense & Linguistic Meaning’
“Frege believed that vagueness could not infect reality itself — the objective entities which our thoughts denote. I suspect that only if one explicates reality in terms of mind or meaning does the notion of vagueness in reality make any sense.”Burge
Burge believes that Frege’s view on vagueness was that it was only possible for it to be an element of our thinking. It could not be an element of objective reality. He then agrees with this himself. Since Frege is writing mostly prior to the advent of quantum physics, Burge is likely to be correct about what Frege thought. We may nevertheless question Burge as to whether “reality” cannot include fundamental vagueness.
Quantum Physics: “Thoughts” and Sense
There are a large number of indeterminate elements to modern physics. There is the Heisenberg Uncertainty Principle. That means that the accuracy of a measurement of the momentum of a particle limits the accuracy of a measurement of its position.
Note that this is not a statement of restricted quality in available measuring equipment; it is a reflection of fundamental reality that we can never know both to arbitrary precision. A further development of this is wave-particle duality. An entity could actually be a wave (with fully defined momentum and “vague” position). Or alternatively, it could be a particle (with fully defined position and “vague” momentum).
Or in a further consequence still, there can be `virtual’ particles. These do not exist in the same way as fully realized particles. They are “within” the limits of the energy that they can “borrow” from the vagueness of the vacuum. These virtual particles nevertheless affect the measured mass of non-virtual particles. Burge could resist the claim that these are aspects of objective reality. But then he must assert that all of these factors are created by minds.
Some elements of quantum physics are heavily influenced by mental action. For example, the inducement of the collapse of wave-functions. But this seems unlikely to extend as far as the creation of virtual particles.
Finally, on a more prosaic level, why are minds needed for vagueness? Where do the root systems of two trees that are intertwining under the ground begin and end? Surely we could make a number of choices of equal validity. A computer could determine the range of choices.
Burge might now insist that a computer is effectively a mind at one remove. That would be because humans create computers. Then we could look at the outlandish possibility of alien intelligences making the decision. But in any case, the fact of the matter about the vagueness of the root systems should be the case independent of whether anyone or anything inspects them. Otherwise there is no objective reality.