Ⅰ．Introduction: Two Kinds of Knowledge

“Philosophy begins in wonder,”Plato so concludes. Humans, as curious creatures, ask questions that concern the world and humanity in order to acquire knowledge. What is the mechanism of quantum mechanics? What is the structure of the world? Can people perform whatever they want to do in the society? Why do I need to obey the moral laws?

However, what if no reliable or practical answer can be given? What if some questions even cause social problems of rumors and turbulence?The first step to answer the presented challenges is to distinguish different questions. Knowledge can be separated into two categories: facto questions that concern fact (e.g., science, epistemology, and metaphysics) and normative questions that concern value and human practice (ethics and normative theory).

This essay proposes two standards to decide whether a question should be asked or not:

1．In the field of facto questions, a question should be asked if and only if a reliable answer can be discovered.

2．In the field of normative problems, a question should be asked if and only if humans can form practical agreements that can direct human practices.

This essay analyzes the two types of questions respectively.