Modern science has produced profound and accelerating changes in the way we live over the last two centuries. Most of those changes have been for the better: for example, life expectancy has increased dramatically and worldwide hunger has likewise decreased. Yet we live in a time of widespread disbelief in, and attacks on, science. These attacks come both from the right of the political spectrum (e.g., climate change denial) and from the left (e.g. refusal of vaccinations). I explore some of the science under assault, and the motivations and methods of the deniers.