Hi,

Which is correct and most importantly, WHY?

I would beat you until you died.

OR

I would beat you until you die.

Is there any one who can tell me the specific rule/tense/whatever that would determine why you would use one or the other?

It would be helpful to have a little context here, because 'would' can be used in different ways.

eg future in the past

Q: When you were young and you didn't do your homework, what would your father do?

A: He would beat me until I died. (Obvously, an exaggeration!) 

Here, the past tense is used. It reflects that this actually happened in the past, he actually beat me and I actually cried.

eg future conditional (which is what I think you are asking about)

Q: I know you always do your homework, but what would your father do if you didn't?

A: He would beat me until I died. (Obvously, either an exaggeration or a harsh father!) 

Here , everything is hypothetical or 'unreal'. The past tense reflects this 'unreality'. We see this more clearly in a simpler example of 'unreality' like 'If I won ten million dollars, I would buy a big house'.

This is a tricky question that you are asking. Other people may offer you other comments.

Best wishes, Clive

 

Simple present doesn't sound right.  You can't die multiple times.  We do use "am/are dying" to give the image of ones health deteriorating.  For example, "If the cancer patient is dying, and he only has 3 months before he will die, he might as well take this experimental treatment to avoid death."  Adding "would" introduces a hypothetical that is not probable.  He didn't take the treatment, and he died after 3 months.  It is now 5 months later, he could have taken the treatment, and the doctors are all wondering, "If he had taken the treatment, would he have lived / (not live)".

Another approach is to see how the tenses work in different situations:

I WOULD:

1. serve you food until you finish / serve you food until you finished
2. watch TV until you return / watch TV until you returned
3. use an umbrella until the rain stops / use an umbrella until the rain stopped

That is as far as I can go without arguing the need for "were".  It seems the sentence "I would ....until you...." is not a complete thought.  It would originate from, "If.... were...., I would....until you...."

You have to state the IF condition in order to clarify the subjunctive.

"If you were a monster in my closet, I would beat you until you die/died."

This is like saying, "If you were a monster in my closet, I would beat you until you WERE DEAD."

Which of the two best matches "were dead"? I go with "died".