The two English modals, can and may are used to express various meanings such as `permission,' `prohibition,' `request,' `order,' `ability,' `possiblity,' etc. Some of these meanings are shared by both, and the others are not. This means that can an...
The two English modals, can and may are used to express various meanings such as `permission,' `prohibition,' `request,' `order,' `ability,' `possiblity,' etc. Some of these meanings are shared by both, and the others are not. This means that can and may have both similar and different properties in their meanings. This study thus aims to construct the semantic structures of can and may that are expectd to explain those properties.
To capture the inherent semantic properties of the tow modals this study begins with the differentiation of the two concepts of possibility: `factual' and `theoretical,' as named in Leech(1971). It is then argued that `factual possibility' is realized by may (epistemic) and `theoretical possibility' by may (deontic) and can. In this study there is no distinction made between can (epistemic) and can (deontic).
on the basis of this distinction this study attempts to construct ;the basic semantic structures of can, may(deontic), and may(epistemic) in order. it is proposed and argued that can sentences have the semantic structure POSSIBLE (DO(a, S)), may (deontic) sentences have CAUSE (x, POSSIBLE(DO(a, S))), and may (epistemic) sentences have CAUSE(x, THINK(SPEAKER, POSSIBLE(S))). These semantic structures tell us about some insightful semantic generalizations on the two modals. First, there is no similarity between can and may(epistemic) except POSSIBLE is shared. Second, may (deontic)implies can, which well explains that may and can are used interchangeably to mean `permission' and `prohibition.' Third, may(deontic) and may (epistemic) have CAUSE in common, thus both being distinguished from can, which lacks CAUSE.