Do vaccines cause autism or save lives? Can we hunt and detect ghosts or are they just figments of our imagination? Is global warming caused by humans or just due to natural climate fluctuations? Does homeopathy actually do anything for us, or is it just drinking water? When we are faced with contradicting claims, how do we know what to believe? In this class, we will look at several debatable scientific and popular issues that have strong claims of veracity on both sides. Our goal in this course will be to understand how to investigate varying beliefs and assumptions from a wide range of sources, and how we come to determine what claims can be supported by evidence, and what claims cannot.