What's our most basic assumptions?

[Testy Calibrate]

What would be our most basic assumption when we try to understand anything about reality?

Hopefully, all properly articulated answers will be entered in a poll to see which one may be best.

You can always submit several answers.

The assumption that there's a reality to begin with doesn't count.

The assumption that one should be clever enough to understand something doesn't count.

I won't submit any answer myself to retain some credibility as a fair judge and competent arbiter. I promise to be fair and impartial.
EB

The one and only assumption we must make is that the universe is consistent