To make a claim that something is true one must give at least an iota of evidence in reality to back up that claim. Ayn Rand rejected subjectivism. That is, she rejected the idea that something is true simply because a person wants it to be true or feels it's true. In epistemology, like metaphysics, reality cannot be wished into existence. Ayn Rand also rejected skepticism.
Skepticism is the belief that knowledge about reality is impossible to obtain.
Ayn Rand believed that absolutes exist and that we can gain knowledge of those absolutes through the use of reason. A skeptic is one who claims, for instance, that reality is unknowable, there are no absolutes, or one cannot be sure of anything. We need a code of values because we have free will. It is the ability to choose to think or not. Man's possession of free will is what allows him to make moral choices.