Moving from the historical roots of Cognitive Science, and considering its present status, I argue that it is not possible to find a single object or method that allows to unify various perspectives into a single disciplinary perspective. Thus, I consider the plural expression “cognitive sciences” more appropriate than the singular one, unless a framework for understanding multidisciplinary collaboration is found. I then briefly describe a meta-theoretic system, suggesting how cooperation between cognitive disciplines may have a true explanatory value. In this system, a single commonsense “fact” is described as a different “state” from the perspective of different disciplines (as a physical state, or a state of the body, of the brain, of consciousness, etc.). Such descriptions include new states resulting from changes of state (“events”), disposed along a time sequence (called “flow”). A parallel representation of different flows, describ ing from various disciplinary standpoints the same events occurring in a certain time course (called a “flow-chain”), allows to establish the nature of correspon dences and links between events in the same or different flows. I argue that a multidisciplinary exchange is really needed for explanation when a cognitive phenomenon includes events that are correlated but cannot be causally linked inside a single flow, i.e. using a set of descriptions belonging to a single disci pline.