the.com/infinite regress

means A chain of reasoning where each step depends on a prior step that needs the same kind of justification, so the explanation never bottoms out and the argument never actually proves anything.

from From Latin regressus, 'a going back,' built on gradi, 'to step or walk' (the same root that gives us 'progress' and 'gradient'). Philosophers bolted on 'infinite' to describe arguments that keep stepping backward forever — each cause needing its own cause, each reason needing its own reason. The 'turtles all the way down' image is a much later folk illustration, often traced (unreliably) to a remark about an old woman and a tortoise holding up the world; nobody can confirm who actually said it first, but it stuck because it makes the abstract logical problem feel like a very tall, very silly stack of turtles.