Many philosophers think that doing philosophy cultivates valuable intellectual abilities and dispositions. Indeed this is a premise in a venerable argument for philosophy’s value. Unfortunately, empirical support for this premise has heretofore been lacking. We provide evidence that philosophical study has such effects. Using a large dataset (including records from over half a million undergraduates at hundreds of institutions across the United States), we investigate philosophy students’ performance on verbal and logical reasoning tests, as well as measures of valuable intellectual dispositions. Results indicate that students with stronger verbal abilities, and who are more curious, open-minded, and intellectually rigorous, are more likely to study philosophy. Nonetheless, after accounting for such baseline differences, philosophy majors outperform all other majors on tests of verbal and logical reasoning and on a measure of valuable habits of mind. This offers the strongest evidence to date that studying philosophy does indeed make people better thinkers.