 Thinking may come naturally to us, but constructive reasoning certainly does not. None of us are naturally endowed with the ability to think clearly and logically, without learning how and without practicing. Constructive thinking is a skill, the same commitment, training and practice that is required to be a good golfer, for building houses or for playing some musical instrument, are also required in order to be a good thinker. Critical thinking provides us with the tools to be better thinkers, to better understand the process of reasoning, to identify flaws in our reasoning and that of others, and it is the foundation of constructive science. Critical thinking is a form of metacognition. It is self-directed and self-monitored. It is about developing the conceptual tools to be able to think for oneself. Critical thinking is about trying to understand our processes of reasoning and developing standards for improving them. It is a way of thinking about any subject in which the person improves the quality of their thinking by assessing, analyzing, deconstructing and reconstructing it to try and improve its clarity, accuracy, relevance, depth, breadth and logical consistency. The course is broken down into four main sections where we will look at the major themes of cognition, logic, reasoning and argumentation. The first section looks at human cognition to understand the basic biological and evolutionary constraints placed on us when it comes to effective reasoning. Here we will talk about how the brain works, look at some of the central insights from cognitive science and talk about some of the many limitations and flaws prevalent within human cognition. In the second section we will look at logic. Although critical thinking is much more than just logic, reason and logic lay at the heart of constructive thinking. Here we talk about the various different forms of logic, inductive, deductive, formal, informal, etc. In the third section we will start our discussion on the theme of reasoning, the process through which we take in information and use some logic to infer conclusions. We will take the process apart to understand the elements of effective reasoning. Here we will talk about the standards of reasoning, elements of reasoning, creative thinking and more. In the final section we discuss the important topic of argumentation, how people with diverse or even divergent opinions come to resolve their differences in order to develop new knowledge, make decisions or reach consensus on some issue. This course is based upon the work of the Foundation for Critical Thinking and is designed to provide an overview to critical thinking that should be accessible to all.