 As regards external objects, Descartes and Locke were realists who held that representations mediate the perception of external objects. Accordingly, perceivers immediately experience sensory ideas that present properties such as shape and color and, through an act of judgment, come to perceive external objects as having properties that cause those sensory  ideas.[6]  Berkeley and Hume sought to turn this position against them by arguing that it has skeptical consequences. They sought to avoid such skepticism, by adopting idealism in Berkeley’s case, which makes really existent sensory ideas the objects of perception, allegedly avoiding skepticism, or adopting a common-sense realism about external objects, in Hume’s common-sense persona.