  Inspired by the early Wittgenstein's concept of nonsense (meaning that which
lies beyond the limits of language), we define two different, yet
complementary, types of nonsense: formal nonsense and pragmatic nonsense. The
simpler notion of formal nonsense is initially defined within Tarski's semantic
theory of truth; the notion of pragmatic nonsense, by its turn, is formulated
within the context of the theory of pragmatic truth, also known as quasi-truth,
as formalized by da Costa and his collaborators. While an expression will be
considered formally nonsensical if the formal criteria required for the
assignment of any truth-value (whether true, false, pragmatically true, or
pragmatically false) to such sentence are not met, a (well-formed) formula will
be considered pragmatically nonsensical if the pragmatic criteria (inscribed
within the context of scientific practice) required for the assignment of any
truth-value to such sentence are not met. Thus, in the context of the theory of
pragmatic truth, any (well-formed) formula of a formal language interpreted on
a simple pragmatic structure will be considered pragmatically nonsensical if
the set of primary sentences of such structure is not well-built, that is, if
it does not include the relevant observational data and/or theoretical results,
or if it does include sentences that are inconsistent with such data.
