Think Again: How to Reason and Argue

Think Again: How to Reason and Argue is a free, beginner-friendly online course from Duke University, taught by philosophers Walter Sinnott-Armstrong and Ram Neta. It offers an accessible, practical introduction to the skills at the heart of critical thinking: understanding what an argument is, breaking arguments down into their parts, and judging whether they are any good.

The course is organized around a simple, powerful progression. Students first learn to identify arguments and separate them from mere assertion, then to analyze their structure, and finally to evaluate them — distinguishing valid deductive reasoning from strong inductive reasoning, and learning to recognize the common fallacies that make bad arguments sound convincing. Along the way it covers categorical logic, propositional logic, and the everyday rhetoric of persuasion, all explained in plain language with abundant real-world examples rather than abstract symbol-pushing.

Because it assumes no background, it is an excellent fit for a motivated homeschooled high schooler ready to go beyond a fallacy workbook, and it pairs naturally with debate practice and persuasive writing. The full video lectures and quizzes are free to audit on Coursera; a certificate is available for an optional fee. For families building a serious logic and critical thinking sequence, this course delivers university-level instruction at no cost — a rare and genuinely valuable resource.