The Basic Functions of English Tenses and their Semantic Realizations in Sentences

The primary goal of this study is to identify the basic functions of the English present and past tenses and their actual realizations within the sentences, which contain no modal auxiliary verbs. These sentences express factuality employing the present tense for timeless facts and the past tense for the facts confined to a past time frame. The semantic realizations of both tenses are determined by a separate operation, in which disjunctions of each basic function and the two determining factors occur. The secondary aim of this paper is to explain the tenses in sentences which contain modal auxiliaries. This paper argues that a future tense never exists as a separate tense, and that futurity is a part of non-factuality expressed by modal auxiliaries. All modal auxiliaries express a present tense which is unmarked and so automatically assigned by the principle, which requires every sentence to have a tense. However, modal auxiliaries are forced to express a marked past tense only when they are used in past contexts.