Research into human models of intuitive physics typically falls into one of two camps, either claiming that intuitive physics is biased and not representative of real physics, or claiming that it consists of a collection of veridical physical laws. Here we investigate the causes of this tension, suggesting that prediction is based on real physics, but explanation is susceptible to biases. We gave participants three tasks based on the same physical principles: two prediction tasks and one task that required drawing the future path of motion. We found distinct biases in all three tasks; however, the two prediction tasks could be explained by consistent application of real physical principles under uncertainty, while the drawing task produced many more idiosyncratic biases. This suggests that different tests of intuitive physics are capturing different types of knowledge about the world.