Even If God Did Not Exist: Grotius's Famous Hypothesis

In the prologue to On the Law of War and Peace, Grotius made a bold claim: what he had said about natural law 'would have a degree of validity even if we should concede that which cannot be conceded without the utmost wickedness, that there is no God'. Grotius himself was a sincere Christian who wrote works of theology, so he was not denying God. His point was that natural law rests on human nature and reason, and would therefore be valid on its own terms.

He also wrote that just as even God cannot make two times two not equal four, God cannot make what is intrinsically evil be good. Some historians see this as a decisive step toward a secular natural law that people of any faith, or none, could share. Others note that medieval scholastics such as Gregory of Rimini had made similar points, so Grotius was developing an existing idea rather than inventing one.