Fact in the Head is a community for evidence-based exploration into the facts in our heads. We cover a wide range of topics, but emphasise discussion of scientific issues as well as those subjects surrounded by confusion, misinformation, and misconception. The purpose of our group is to promote the habit of backing up claims of fact on social networks. We also encourage discussions on how to decide what makes for quality evidence and how to distinguish it from the less credible. We seek to make commonly accepted claims seem strange and counter-intuitive truths seem normal. Too often we accept claims as a fact, but we don’t analyse those claims thoroughly and critically. Not only that, but we frequently don’t even remember where we learned information, yet we trick ourselves into false confidence of our knowledge. For these reasons, discussion here should focus on high-quality facts, credible sources, and scientific literature. We should challenge other people’s claims, but also have the courage to challenge what we ourselves think we believe.