Unlike the methods of early scientists, Sir Francis Bacon believed basic laws of science should be determined by using inductive reasoning based on empirical evidence. You cannot formulate a law in science if you don't have evidence to support it - so you cannot just take a basic truth and formulate your law based on that - there has to be some kind of evidence to prove your theories. Also, based on those evidence, you will induce a conclusion necessary for such laws, which is something Bacon understood, unlike early scientists.