4.7.7—
The Four Modalities

The expression 'is a marker' has been replaced by four locutional schemas that have been given technical definitions:

—'is interpretable (under convention C of linguistic group L ) as a marker of type M '

—'was intended (by its author S ) as a marker of type M '

—'was interpreted (by some H ) as a marker of type M '

—'is interpretable-in-principle as a marker'

To these four locutional schemas correspond what might be called four modalities of conventional being, or four ways in which an object can be related to a conventionally established type (though in the case of interpretability-in-principle, the conventions and the type need not be actual). These four modalities can be applied not only to markers, but to other conventionally established types as well, as we shall see presently. These locutional schemes, moreover, are intended to capture and distinguish four different senses in which one might speak of an object "being" a marker (e.g., a letter or a Morse code dot) or "being" of one of the other conventionally established types. These different senses are, to some extent, already operative in ordinary and technical uses of the word 'symbol', but existing terminology is not subtle enough to distinguish the different senses.