How do we know when something is valid?

How do we know when something is valid? What sources of truth do you accept? What is the purpose? Do you accept the findings in science and psychology? Do you believe that there is truth in personal experience? Given that this is a beginning perspective on how you would conceptualize integration, you will find issues that remain unsolved for you. Do you feel that there is truth in logic and philosophy? Talk about the limitations of each one. Critique the conflicts and inconsistencies with science, personal experience, and philosophy as well as the sub topics. Areas that you can not address in these topics but would potentially like to address in the future. What are your three sources of truth?