We are all thinking all the time. With some of us it might not always appears so, but our minds are running constantly. Opinions, beliefs, evidence, or facts; all these elements combine and form in our minds.
Critical thought is a manner of thinking that will lead to greater and more factual understanding of the universe. It relies on measurements and evidence and avoiding problems in thinking to reveal truths and separate it from falsehoods.
But truth is an ongoing process. Truth is always tentative. In this discussion Jesse and Paul get into the complexity of it all to break it down and simplify it.