Not to get all metaphysical, but shoes have soles. It's a known and indisputable fact. All you have to do is look at a shoe and it is immediately apparent that it has a sole. There's no doubt about it. What might be a little more difficult to objectively confirm is the existence of the inner sole. While the outer sole is readily observable, confirming the existence of the inner sole requires an inspection of the interior of the shoe. It is necessary to look inside the shoe and after almost no searching it is completely obvious that the inner sole indeed exists and there is virtually nothing mysterious, inscrutable, or enigmatic about it. For this reason, proving the inner sole's actuality is not too awfully difficult and so there can be little, if any doubt, that the inner sole of a shoe also exists. It's not a matter of faith or something which requires holy guidance or spiritual discernment. It's just a simple matter of fact.