Philosophical Foundations

https://www.quora.com/Does-proof-need-proof-that-the-proof-is-real-How-do-we-truly-know-for-certain-if-anything-is-truly-right-or-wrong

A reply
Anže Rupnik, I'm an engineer
Answered Jul 18, 2018
If you float on a raft in the middle of the sea, how can you be sure that you are moving? ...


While foundations are vitally important, and certain question are difficult (at that moment), you are already presupposing you have knowledge of  the raft, the sea, that something called floating exists when an object moves on the surface of water, and the statement that you are in the middle of the sea suggests you cannot see something that is not sea (or called land).  What is your foundation for any of that?  Even at that moment also bring into your awareness that seas move in currents, seas on our planet move in multiple rotations, the planet moves in its own rotation, around the sun, within a galaxy, etc.  You have already assumed the truth of moving or not moving by that which you are comparing this moment to.  The foundation of movement has already been established for you to ask the question.

Just because the automobile in the lane next to me is moving passed me at one mile-per-hour does not inherent disprove my knowledge that both vehicles are moving at seventy miles-per-hour down the roadway.  Even if at one particular instant there is moment of uncertainty that does not discount that I can add to it further evidences.  In many ways we can bootstrap foundations of what we do not know from other foundations that we do know.  Knowing that we need foundation presumes that we already have experienced (in the physical world of rafts) foundations that then provokes us to believe that conceptuality is useful for questions about anything.