it was Descartes you set out the new metaphysics so he is the one who originated the fundamental properties. The only way that you and I know that the fundamental properties of Descartes is valid is to ask yourself if the arguments that he makes are sound. If they are sound then you can accept them as valid arguments and accept the fundamental properties. However, if you accepts them as unsound arguments depending on which argument you consider to be unsound, you can refute all the arguments or refute a few of them.Locke on the other hand is not developing any new fundamental properties. He is fixing the old fundamental properties held by the scholastics. All he is doing is keeping with that sensory perception is the only way to obtain knowledge, but agrees with Descartes by saying that you should be cautious. Locke really doesnt know if the fundamental properties of the science are those the new science identified as fundamental. They could be fundamental or they could not be. The mind has limited knowledge and if the mind doesnt know and hasnt obtained the knowledge from sensory experience then you wont know unless you do. Locke is a very conservative person, he is not overstepping his bounds by making claims about things that he can not prove, so he plays it safe and he stay within the realm of the knowledge and doesnt delve into areas that he can not know anything of....
