In the international bestseller 'Thinking, Fast and Slow', Daniel Kahneman explains how we as human beings think and reason, and perhaps surprisingly how our thought processes are often fundamentally flawed and biased. This talk explores the ideas presented in the book in the context of professional software development. As software developers we all like to think that we are highly logical, and make only rational choices, but after reading the book I'm not so sure. Here I'll share my thinking on thinking. Topics that will be discussed include; the 'Availability Heuristic', which can lead developers to choose the 'latest and greatest' technology without proper evaluation; 'Optimistic Bias' which can blind architects from the 'unknown unknowns' within a project; and more!