Just because two authors disagree over one point, does not necessarily mean that they disagree on all points. For example, just because a second author disagrees with the first's conclusion, does not necessarily mean s/he disagrees with the first author's premises or introductory information. Oftentimes LSAT point at issue questions are structured in this way:

	Author 1: Premises V, W, X. Conclusion Y.
	Author 2: I disagree with Conclusion Y because of Premise Z.

 

We don't know what Author 1 thinks of Point Z. Also, we don't know what Author 2 thinks of Premises V, W, X. We only know that the two disagree over Conclusion Y.