  To provide an explanation of the evolution of scientific knowledge, I start
from the assumption that knowledge is based on concepts, and propose that each
concept about reality is affected by vagueness. This entails a paradox, which I
term Knowledge Paradox (KP): i.e. we need concepts to acquire knowledge about
the real world but each concept is a step away from reality. The KP provides a
unifying context for the sorites and the liar paradoxes. Any concept is viewed
as a sorites, i.e. it is impossible to set a boundary between what is, and what
is not, the entity to which the concept refers. Hence, any statement about
reality can be reduced to a liar, wherefrom the KP follows in its most general
form: -If I know, then I do not know-. The KP is self-referential but not
contradictory, as it can be referred to two levels of knowledge: -if I
know(epistemic), then I do not know(ontic)-, where the ontic level is made
unachievable by concept vagueness. Such an interpretation of scientific
knowledge provides an understanding of its dynamics. Concept proliferation
within theories produces periods of knowledge decay that are episodically
reversed by the formulation of new theories based on a smaller number of
synthetic concepts.
