Epistemic modality and evidentiality are two categories that have not been clearly defined in the literature. In order to clarify the boundaries between them, I draw a detailed semantic map for Catalan modal verbs deure (‘must’), haver de (‘have to’) and poder (‘can/may’) in the Old period (11th–16th centuries). On the one hand, the modals deure and haver de develop an evidential reading (inferential process). On the other hand, an epistemic possibility value arises in the case of poder, which is not based on any explicit premise. I show that all these verbs are subjectively construed in different degrees and argue that a clear distinction between the subjective values and an evidential or epistemic interpretation is paramount.