Apparent progress due to a 'wall' restricting where random change can take things.

Adapted from Gould 1996. Others [cf Nitecki 1988] claim that there is only progress because any increase over zero is a net increase, and that different measures will give different results. The traditional notion of progress as an increase in perfection or optimality has been abandoned, for it rested on a view that goes back to the late neo-Platonists - the idea that all of reality is arranged in a heirarchy of increasing perfection. This is called …

…explanations that are sometimes called teleology: telenomic (goal-seeking, Aristotle's final causes, 'for-the-sake-of-which' explanations); teleomatic (lawlike behaviour that is not goal-seeking); adapted systems (which are not goal seeking at all, but exist just because they survived); and cosmic teleology (end-directed systems) [cf O'Grady and Brooks 1988]. Only systems that are actively directed by a goal are truly teleological. Most are just teleomatic, and some (e.g., genetic programs) are teleonomic (internal teleology), because they seek an end.