Visual Illusions?

The very definition of “illusion” is elusive. Various distinct ontologies are considered. The concept is tightly bound to the understanding of reality, awareness, “God’s eye,” objectivity, subjectivity, emphatic relations, and several others. Here the distinctions between “illusion,” “ambiguity, “delusion,” and “deception,” are clarified. The very notion of illusion is closely tied to conceptual approaches to mind. Especially the dichotomy between a top-down “controlled hallucination” and a bottom-up “inverse physics” approach accounts for much confusion in the literature. It is suggested that a thoroughly biological approach might be preferable. In such an approach, experimental psychobiology would be a special sub-branch—devoted to the genus homo—of ethology. Does this help to impose a formal structure, such as a partial order, on the zoo of illusions as we know them? Unfortunately, not really. At this moment in history, we are still far from such a reasoned inventory.