Bdtyk

I have been thinking about the following sentence for a while:

Let's say you have a room that contains a single light source and a single table, and that you choose a point on that table.

When I read it, I get the feeling that the that should be replaced with the. I feel this way because the sentence seems to be talking mainly about the room. Am I correct in my assumption? Or are the two interchangeable?

If the person has already identified the room, the light source and the table, which in this case they already have then now they are talking about the specific table he has just mentioned and now visualises in his mind. So he is saying that table which we are going to use in that particular room with that particular light source because they all have been identified and are no longer just any room, any light source or any table. If he went on to talk about the room or light source again he would use that to identify them as well...... 'and that you would choose a point on that particular table, in that particular room and shine that particular light on it, the spot where the light shone would glow..........' (or maybe you are right and I am just trying to justify an error)

"That" is actually better here, although both would work.

Using "that" like this is very common in hypothetical statements:

"Once upon a time, there was a magical kingdom. And in [this/that/the] kingdom, there lived a princess."

My intuition tells me "that" sounds better, because "that" sounds like we're distinguishing something (in this case, the kingdom) from some other thing (like another kingdom), and neither of them are immediately visible.

It's all just a matter of preference though.

P.S. There's actually a song which uses this hypothetical "that" over and over again. It's called And The Green Grass Grew All Around. Here are the lyrics:

Oh in the woods there was a tree
The prettiest tree

You ever did see

And the tree was in the ground

And the green grass grew all around, all around, and the green grass grew all around

And on that tree

There was a limb
The prettiest limb

That you ever did see

And the limb was....

...

And on that limb

There was a branch
The prettiest branch....

So you can see that the pattern goes from 'a' --> 'the' --> 'that'.

"A tree," to introduce the object "tree."
"The prettiest tree," to specify that it's not just any tree, it's the tree.
"That tree," to indicate that you're talking about the tree that you were just saying something about earlier.

That's kind of the best way I can explain it.

This is a great question; and as an aspiring writer it’s something I struggle with at times as well. One article I reference for generally on when to omit using the word “that” is here:
https://www.bkacontent.com/avoid-overusing-word-writing/

“Let's say you have a room that contains a single light source and a single table, and that you choose a point on that table.”
This is technically an incomplete sentence because what comes next. Why was the point of the table chosen, or where is the sentence going towards a close? Depending on the full context and sentence structure, either “that” or “the” would be used.

Generally speaking however, the word “that” in and of itself is restrictive. It is used to specify something in this context, given what we have here, the closing in the sentence referencing “that” table. The problem is, the sentence states in the beginning there is a single light source and a single table in the room; so it is already understood only one table exists in the room in question. This is why using “the” table here is appropriate as there is no need to specify a certain table when only one exists in the room.

On another note, the lady or gentleman’s example:
"Once upon a time, there was a magical kingdom. And in [this/that/the] kingdom, there lived a princess."

The proper structure for this sentence is:
"Once upon a time there was a magical kingdom, and in this kingdom there lived a princess."
Notice how the sentence flows and the word “this” is used here as from the writer’s prospective of telling the story and also distinguishes the magical kingdom. Plus, it is grammatically incorrect to begin a sentence with the word “And” as the word is a conjunction.

I do love you’re example of the song lyrics and the hypothetical “that” is used there correctly to eliminate over repeating.

I hope this is helpful!