The skill of perception The newborn baby and the [blind man suddenly gifted with sight] do not have to learn to see. Sight is given to them. But they do have to learn to perceive. Perception is learnt and learnt slowly. Skill is required for perception as for speech. We are largely unaware of the skill we exercise. None of the things we have to learn to perceive are self-evident, or, apparently, instinctively evident. No doubt, however, we have an instinctive aptitude for this learning, and once we have learnt we cannot easily see as though we had not. As Ruskin says, one has to strive, if one is to see with the 'Innocent Eye'. David Pye, The Nature and Aesthetics of Design The innocence of the eyethe innocent i seeingperceptionlearninginstinct
Changing constraints The Constraints Keep Changing The explicit listing of known constraints in the design program helps here. The designer can periodically scan the list, asking, “Can this constraint now be removed because the world has changed? Can it be entirely circumvented by working outside the design space?” Frederick P. Brooks, Jr., What's Wrong With This Model? What's wrong with the rational model constraints