I mean, it's hard to know where to start. The sibling poster gave a practical example about leaving your house. Another might be: "what happens when I burn hydrogen in oxygen? Will it produce water, ammonia or a chocolate bunny?". Chemistry rather than simple quantity is our object here, so you can't know with the certainty of math. You can't know with absolute certainty that hydrogen won't suddenly change its properties today and give you ammonia or chocolate. Would you therefore answer "I don't know"?

Another problem is that your position appears to be self-refuting. Your proposition is that "Everything I know, I know with the certainty of math, or not at all". Which of the two does this statement itself fall into? If it's with the certainty of math, why do you make an exception for this non-mathematical proposition, and how do you justify it, and how do you deal with the ensuing infinite vicious regress? If not at all, obviously it means nothing.

You also need to know with certainty that "something exists". This is true even if the objects of your thought are mere mental images, because even then, mental images exist.

Quite a few other problems but these initially spring to mind.

> "what happens when I burn hydrogen in oxygen? Will it produce water, ammonia or a chocolate bunny?"

I don't know. Does it matter? Even if I plainly see it produce a chocolate bunny, for what reason would I need to make up my mind on that? I fail to see the utility. "I don't know" remains a sufficient state going forward.

> Which of the two does this statement itself fall into?

I don't know.

> If it's with the certainty of math, why do you make an exception for this non-mathematical proposition, and how do you justify it

I don't know. And I don't have a justification. For what reason would I need one?

> and how do you deal with the ensuing infinite vicious regress?

Infinite regress implies making up a mind, no? But since there is no real need to do that...