Part of the Analytical reading process.
In judging a theoretical book a reader should observe identify of or discrepancy between their own basic principles and assumptions and those of the author. For practical books, it's about goals and ends.
You can suspend judgement if the author failed to solve the problem because their analysis is incomplete, or stated an inadequate problem.
Ask questions while you read (Questions to ask while reading a book):
Is it true?
What of it?