[ '.'] So I've been thinking lately: Can we know anything with absolute certainty?

nope but there are things that are generally accepted as truth by all people. because nothing in all the time we have been on this earth has proved it wrong and many times over and over we have tested something and it comes out true. such as 1+1=2 every time we contemplate it we get 2. everyone the world over would tell you that it equals 2 so it is accepted that 2 is known as the answer for certain to the previous equation. logic is math.