The English modal auxiliaries "can", "could", "may", "might", "must", and "should" are notoriously quirky and much has been written about their interaction with tense. To get a perspective on the idiosyncrasy of English modals, it is instructive to look at modal verbs in a language where they are morphologically regular such as Finnish.

The Finnish verb system consists of four moods: indicative, conditional, potential, and imperative. In the indicative mood, verbs have four tenses: present, past, present perfect, and past perfect. In the conditional and potential mood there are just two tenses: present and past.

In this talk I will concentrate on the semantics of "saattaa", "taitaa", and "mahtaa" which roughly correspond to "may" and "might" in English. In contrast to their English counterparts, the Finnish modals have regular paradigms. For example, "saattaa" (may) has four tenses in the indicative and it also has the expected conditional ccccause("saattaisi", "olisi saattanut") and one potential ("saattanee") form.

I will suggest that the best way to view the semantics of the modal operators and their interaction with tense and mood in Finnish is in terms of probabilities and conditional probabilities. Thus the basic meaning of "saattaa" (may) is 'there is a non-zero probability that'. The potential mood means 'there is more that 50 probability that'. Consequently, "saattanee", the potential of "saattaa", is more uncertain than the indicative modal.