We sometimes violate social norms in order to express our views and to trigger public debates. Many extant accounts of social norms don’t give us any insight into this phenomenon. Drawing on Cristina Bicchieri’s work, I am putting forward an empirical hypothesis that helps us to understand such norm violations. The hypothesis says, roughly, that we often adhere to norms because we are systematically blind to norm-violating options. I argue that this hypothesis is independently plausible and has interesting consequences. It implies, e.g., that some experimental paradigms for investigating social norms have hitherto unnoticed shortcomings.