March 12, 1685

Philosopher George Berkeley was born in Kilkenny on this day in 1685. Berkeley’s most substantial contribution to philosophy was his theory of “immaterialism,” or “subjective idealism.” He combined empiricism (the belief that knowledge comes only from direct sensory experience) with idealism (the belief that reality as we know it is mentally constructed) concluding that material substance does not exist, but our perceptions of it do. Berkeley is associated with the phrase, “to be is to be perceived.” However, he didn’t believe that physical objects cease to exist when not being perceived, explaining that God always perceives of everything. In contemporary terms, this describes the world as an interactive illusion, similar  to “The Matrix,” but with God in place of the machines.