"depend only on" sufficient or necessary?

[hrhyoo]

Hi Powerscore,

The phrase "depends only on" is classified as a sufficient condition indicator in the Bible. Could you please explain why? If we drop "only" so "depends on," then is it a necessary condition indicator? I am so confused. Please help!

Hanna

[James Finch]

Hi Hrhyoo,

This is one of the many odd English constructions that just has to be memorized. "X depends only or soley upon Y" is synonymous with "if we know Y, then we know X," as Y is the sole determining factor for X, making it both sufficient and necessary for knowing the outcome of the other condition. Essentially it's the same as saying "if and only if," as knowledge of either Y being true or not would then determine whether X is true or not, and vice versa. Diagrammed:

Y X

and

Y X

With that said, I can't think of a single case of this phrase coming up on an LR question.

More common is the "depends on" phrasing, which as you note is a necessary condition indicator. This is especially common in necessary Assumption question stems, so be sure to know what you're looking for if you run into it there. A common example would being something like "the argument depends upon which one of the following assumptions."

Hope this clears things up!

[hrhyoo]

Thank you, James!

H