Developing the view that philosophy is acquisition of knowledge also requires answering the question: What is the role of non-deductive rules and deductive rules in knowledge? The role of non-deductive rules is to obtain hypotheses to solve problems, the role of deductive rules is to deduce solutions to problems from hypotheses. This depends on the fact that non-deductive rules are ampliative, deductive rules are non-ampliative. Several arguments have been advanced against the claim that deductive rules are non-ampliative, but this chapter argues that they are not valid.