Why "the" in "Three Men in a Boat (To Say Nothing of the Dog)"? [closed]

When reading the title of the book, we don't know what three men it is talking about so there is no/indefinite article (the same with "a boat"). But why is there "the Dog" instead of "a Dog"? We don't know anything about the dog either.

Update: Thanks for the answers. However, I'm not sure why the question got down-voted. I'm not a native speaker and my language has no articles, so using them properly and knowing different corner cases in English poses a problem for me. Honestly, I'd like to know the reasons for down-votes so that I could ask better/more qualified questions in the future. So I kindly ask people who down-voted to explain the reasons.

Solution 1:

The use of "the" suggests a certain, particular dog which will soon become, or is already, connected to the three men. In contrast, "a boat", with an indefinite article, implies less connection between the men and the boat, that it is not a particular boat.

Completely off-topic, the 1930s Czechoslovak Head of State Emil Hacha was an expert in English literature known for his translation of this charming book into Czech.

Solution 2:

Do we know which boat is being talked about? No. It could be a white boat, a blue boat, a large boat, a tiny boat, a new boat, or an old boat.

But – do we know which boat is being talked about? Sure we do! It's the boat that the three men (to say nothing of the dog) are floating in.

So, we can say "Three Men in a Boat" or "Three Men in the Boat." Neither would be incorrect.

Likewise, do we know what men we are talking about? No; for all we know, they could be butchers, bakers, or candlestick-makers.

But – do we know what men we are talking about? Of course! We are talking about the three men who are in the boat. So "The Three Men in a Boat" would also be a valid title.

You can repeat this exercise with the dog, if you want. But saying that the article gets chosen based on "what we know" about the subject is an overly simplistic way of stating it, and that method ignores any inferred context.

Solution 3:

In this title, the dog is mentioned after the men have already been established as the subject of discussion. So when you mention the dog, it's not just any dog; it's the dog that goes with the men who are already under discussion. This specific dog requires a "the". Here are some other possible titles for that book. In most of them, only one of "a dog" and "the dog" sounds right to me. As you can see, it's not easy to give rules that pinpoint the point at which the subject of discussion becomes established, but I suspect most native English speakers will agree on it.

Three Men and a Dog in a Boat
Three Men in a Boat, and also a Dog
Three Men in a Boat, and a Dog as Well
Three Men in a Boat, not to Mention the Dog
Three Men in a Boat—Oops! I Forgot about the Dog
Three Men in a Boat (There was a Dog in it, Too)
Four Men in a Boat (Including the/a Dog)