For Ordinary Language philosophy, at issue is the use of the expressions of language, not expressions in and of themselves. So, at issue is not, for example, ordinary versus (say) technical words; nor is it a distinction based on the language used in various areas of discourse, for example academic, technical, scientific, or lay, slang or street discourses – ordinary uses of language occur in all discourses. It is sometimes the case that an expression has distinct uses within distinct discourses, (...) for example, the expression ‘empty space’. This may have both a lay and a scientific use, and both uses may count as ordinary; as long as it is quite clear which discourse is in play, and thus which of the distinct uses of the expression is in play. Though connected, the difference in use of the expression in different discourses signals a difference in the sense with which it is used, on the Ordinary Language view. One use, say the use in physics, in which it refers to a vacuum, is distinct from its lay use, in which it refers rather more flexibly to, say, a room with no objects in it, or an expanse of land with no buildings or trees. However, on this view, one sense of the expression, though more precise than the other, would not do as a replacement of the other term; for the lay use of the term is perfectly adequate for the uses it is put to, and the meaning of the term in physics would not allow speakers to express what they mean in these other contexts. (shrink)