Over time, they will spontaneously regress without treatment. This is growth of abnormal new vessels; this may regress, but frequently progresses. Warts can also spontaneously regress (with or without treatment). Their mockeries cause Pennywise to surprisingly regress physically and mentally into a helpless infant. Foundationalism is an attempt to respond to the regress problem of justification in epistemology. His explanation leads directly to infinite regress. There seems to be an infinite regress of sentences getting their meaning. Such a situation would lead to an infinite regress. Foundationalism and the other responses to the regress problem are essentially defenses against skepticism. Another argument against cognitivism is the problems of Ryle's Regress or the homunculus fallacy. Untreated, small polyps may regress on their own. Indirect realism is argued to be problematical because of Ryle's regress and the homunculus argument. The expression has been used to illustrate problems such as the regress argument in epistemology. So ultimately grounding has to be sensorimotor, to avoid infinite regress (Harnad 2005). "Turtles all the way down" is an expression of the problem of infinite regress.