One of Diamond’s key goals in this book is to refute the claim that different peoples have fared differently throughout history for biological reasons. Darwinian theory has been particular influential in this regard, and Diamond believes that, even today, people are still liable to believe that some types of people are inherently superior or inferior. This highlights the moral rationale behind this book: Diamond argues that such notions have perpetuated racist thinking, and he is not willing to let this go unchallenged. Despite racism being deemed socially unacceptable, Diamond maintains that some people may still harbor these beliefs, even if they do not express them outright. He consequently states that these misplaced beliefs are motive enough for him to write this rebuttal.

Diamond certainly agrees that history has consisted of “haves and have nots” but he contends that notions of biological superiority/inferiority are incorrect and damaging. He points to the flaws in previous studies that have attempted to establish this biological origin; namely, that it is hard for a testing procedure to isolate cultural background and upbringing from innate intelligence. Diamond therefore concludes that these kinds of tests have failed to provide any sound evidence of genetic deficiency.