 Finally, one may also combine deontic and epistemic or doxastic logics. Such combinations may serve two distinct aims: to capture distinctively epistemic obligations such as “Jane ought to know that there is no cure to this illness (as she is a doctor)”, or to study subjective, knowledge-dependent obligations as in “Given what you know about their production, you ought not to buy these clothes”. For a famous puzzle concerning the first type of extension, see supplement F on  the Paradox of Epistemic Obligation.