Critical thinking is a skill that must be developed, not something we are born with. It involves analyzing arguments and claims to determine their validity based on evidence. There are degrees of certainty, and different people have different thresholds for what they consider valid. When evaluating an argument, it is important to understand the type of claim being made (fact, value, or policy), who has the burden of proof, and what key issues need to be addressed to make an informed decision. While knowledge and intelligence are important, critical thinking is a separate skill that must be deliberately trained through practice.