Why did Bertrand Russell care so much about the meaning of the word "the"?

This post is a letter to my 19-year old self, sitting in a "Philosophy of Logic and Language" lecture, and wondering whether I've made a terrible mistake.

"I would give the doctrine of this word" writes Bertrand Russell "if I were dead from the waist down and not merely in a prison."

You begin to wonder if being in prison (and so having nothing better to do) is a pre-requisite for caring this much about the word "the".

You signed up to this elective "Logic and Language" module because you wanted to learn how human language is structured and how it relates to the world. You figure that if you study hard you will maybe learn how to build computers that can use human language and, and maybe even use human language to think.

The lecturer puts up a slide: "Let's recall that, according to Russell, a denoting phrase may either not denote anything: e.g. 'The present King of France'¹, or it may denote one definite object: e.g. 'The present King of England', or it may denote ambiguously: e.g. 'a man' denotes not many men, but one unidentified man."

You sigh quietly and look around. The eyes of many attendees in the lecture theatre have visibly glazed over. This is the third week in a row of dry quibbling over these kinds of semantics. When is the real philosophy going to start? You are losing hope that it ever will.

In the first lecture you raised your hand and asked why we should study sentences like these, given word "the" doesn't even exist in some of the most commonly spoken languages worldwide. The lecturer gave a cryptic and unsatisfactory reply about ontological commitments and the underlying logical structure of language - that left you feeling like this stuff was simultaneously very complicated and also not really worth trying to understand.

I am sorry you went through this. It did not need to be this way. Let me try and convince you that this stuff is worth understanding after all.

Let's shift our focus slightly. The purpose of this field of study is not that we are arbitrarily interested in the English word "the" and its use. Instead, we're interested in the logic of how descriptions can be used as a way to pick out objects to talk about. This is different from studying any particular grammatical or linguistic structure.

If, like me, you got into studying this stuff because you wanted to understand how human language relates to the world - this should already feel a lot less arbitrary. Picking out objects to talk about is an essential part of human communication. It is the first step in the process of telling each other about properties those things might have, which in turn, is part of how we fill in the gaps in one another's knowledge. There are some cases of doing this which are relatively simple:

• We can describe things that are physically present by gesturing towards them; for example when pointing or looking at a chair you can say: "sorry, that seat is taken".
• Other times we can describe things that have names; for example if you and I know a child called Sam, I might say "Sam is so tall now!".

Bertrand Russell, in particular, helped draw a lot of attention to some more complex phrases which talk about a particular thing without naming or pointing at it. In English nearly all of these happen to use the word "the". E.g: "the center of mass of the universe", "the smallest prime number", "the winner of the next general election". Not all languages have a word for "the", but there are ways to express similar thoughts in languages spoken all over the world. It is the logical structure of these kinds of phrases that Russell was so specifically motivated to write about.

Okay, so why did Russell care so much about phrases which describe things without naming or pointing at them?

Let's return to 19-year old me, sitting in lectures and pondering this question. I believed that the answers were things like:

• We're trying to give logical accounts of all the main structures in language. We've gotten the easy ones out of the way, corresponding to words like "and" "or" "not" "all" and "some" out of the way, so it's time to move on to other commonly used words, and "the" happened to be top of the list.
• We're trying to make sure that there isn't a way to get tricked into talking about non-existent things. The word "the" can be abused in all sorts of ways to do so: e.g. "the square circle", "the present King of France", "the largest number", so we need to understand how it works to avoid this.

I guess these reasons kind of make sense - however my view nowadays is that they miss the point. Notwithstanding that - I also don't find either reason particularly motivating, and they certainly don't seem to justify Russell's own fanatical devotion to this topic.

The point I had missed is given by Russell right on the first page of his 1905 paper about definite descriptions. Right afterwards he gives a very motivating example relating to the problem of other minds.

From reading this page, it becomes clear that the core thing that makes the analysis of definite descriptions interesting is that it helps us answer the following puzzle: how is it possible to talk about something that neither of us has ever directly experienced?

In the rest of this post I'll quote directly from this page to try to break down exactly what I think Russell was trying to say.

To answer this puzzle, first, Russell points out that it is not just a question of how logic and language work, but a question of knowledge works, and in particular how we can know about things that we haven't directly experienced. He then clarifies this by introducing a distinction between knowledge by acquaintance and knowledge by description.

"The subject of denoting is of very great importance, not only in logic and mathematics, but also in theory of knowledge. For example, we know that the centre of mass of the Solar System at a definite instant is some definite point, and we can affirm a number of propositions about it; but we have no immediate acquaintance with this point, which is only known to us by description. The distinction between acquaintance and knowledge about is the distinction between the things we have presentations of, and the things we only reach by means of denoting phrases."

Russell's point is that without these sorts of phrases, we would only be able to communicate knowledge about things with which we have been "acquainted". This would mean that no human could say anything at all about e.g. "the center of mass of the solar system" unless we have experienced it directly.

He then points out that it is in fact very useful to be able to talk about things that we aren't directly acquainted with:

"It often happens that we know that a certain phrase denotes unambiguously, although we have no acquaintance with what it denotes; this occurs in the above case of the centre of mass. In perception we have acquaintance with objects of perception, and in thought we have acquaintance with objects of a more abstract logical character; but we do not necessarily have acquaintance with the objects denoted by phrases composed of words with whose meanings we are acquainted."

To help make this point he gives an example that I personally find very motivating²:

"To take a very important instance: There seems no reason to believe that we are ever acquainted with other people’s minds, seeing that these are not directly perceived; hence what we know about them is obtained through denoting."

I like this example a lot, but it is worth thinking about how fundamental the other much simpler examples above are too. If we were only capable of talking about things we know by acquaintance then it would be incredibly detrimental to our ability to set out to do any kind of interesting discussion or inquiry about stuff that we are yet to be acquainted with. Imagine planning an experiment to measure "the boiling point of water" or setting out to discover "the cause of the common cold" while only referring to things you can perceive.

Hopefully this helps to illustrate why definite descriptions are so interesting. They are the tool we use to think beyond just what we can directly see or touch. In Russell's words:

"All thinking has to start from acquaintance; but it succeeds in thinking about many things with which we have no acquaintance."

For this reason, studying definite descriptions (including all these tricky phrases that use the word "the") is essential for being able to understand the way we learn things about the world. It's also essential to making sure that we don't confuse ourselves when we are in the middle of such inquiries and trying to make sense of what we have learnt.

In the rest of the paper Russell's goes on to give his own (controversial) analysis of the logical structure of definite descriptions. It’s an analysis I have never felt is wholly right. But for the reasons above I think he was entirely correct in identifying definite descriptions as an important topic of study. Perhaps more importantly, by reflecting on Russell’s motivations, we can see that this topic of study is as much about epistemology as it is about logic, and I think that we miss a lot when we let the latter overshadow the former.