M.A. (Psychology) / Despite well over two millennia of philosophical speculation and just under a century of objective, standardized measurement, students of intelligence are far from unanimous in their agreement on a formal definition of the concept. Biological, psychological and operational definitions have each been advanced' and criticized in their turn. The majority of definitions, particularly of the psychological variety, have been variously rejected as circular, question begging, over-inclusive or value-laden. Such definitions have included the capacity for learning; the capacity to act purposefully, think rationally and deal effectively with one's environment; the ability to perceive or educe relations; and the ability for abstract thinking, to mention but a few...