using this week and next week

What is the proper usage of "this week" and "next week"? For example, if tomorrow is Saturday is it next Saturday or this Saturday? I've been arguing lately that next Saturday should be a week from tomorrow, but if I had said "the next Saturday" then that would be tomorrow. If next Saturday is tomorrow then when is this Saturday? Please help clear this up for me.

[Casiopea]

Originally Posted by Shern

What is the proper usage of "this week" and "next week"? For example, if tomorrow is Saturday is it next Saturday or this Saturday? I've been arguing lately that next Saturday should be a week from tomorrow, but if I had said "the next Saturday" then that would be tomorrow. If next Saturday is tomorrow then when is this Saturday? Please help clear this up for me.

If the day is a part of this week, then it's this Saturday, and if the day is a part of next week, then it's next Saturday.

Today is Friday
Tomorrow, or this (coming) Saturday, I have to work.
A week from tomorrow, or next Saturday, I have the day off.

Note, "next" means, the one after this, so "next Sunday" means, the Sunday after this coming Sunday. But. . . not all speakers use it that way, so when in doubt, be as specific as possible: use "tomorrow", or "the day after tomorrow", or "two days from now", and so on.