You are make assumptions that are strong for claiming to be a skeptic.

To go through them: 1) Tied shoelaces also allow you to tie them again. Untiedness is no requirement for tying. 2) If you are in a social environment where untied shoes are really cool then tying them might decrease your utility. At the same time tying them still makes them tied.

Okay, I really shouldn't have stated those specifics. Instead, in order to tie shoe-laces successfully, all one really needs to know is that performing a series of actions that are commonly known as "tying your shoes" typically results in one's shoelaces being tied.

3) It's quite possible to tie your shoes through muscles movements that are not commonly used for tying your shoes.

I never said that the muscle movement were common, just that they typically resulted in tied shoes.

That said, I'm not really sure how this is relevant. Could you explain?