The question tackled here centres on the notion—or, more precisely, the many notions—of theory often used in discussing scientific matters. The analysis that we attempt develops within the framework of the anthropo-logical theory of the didactic (ATD). It purports to show that current usage refers mostly to the " emerged parts " of so-called theories and largely ignores their " immersed parts " , which are the correlate of their intrinsic implicit-ness and historical incompleteness. This leads to favour open theorization over entrenched theory.