For Quassim Cassam, intellectual vices obstruct knowledge. On his view, that’s what makes them vices. But obstructing knowledge seems unnecessary. Some intellectual vices can manifest passively, without obstructing knowledge. What’s more, obstructing knowledge seems insufficient. Some traits of intellectual character, not yet matured to full virtues, obstruct knowledge but earn us no blame or criticism. A motive-based theory of intellectual vice – a rival theory – can handle both of these issues.