Empiricism or rationalism?

This was an eye opener for me. I had always thought myself rational, although I had recognised that a logical structure built on false assumptions is valueless, and possibly dangerous, and thus we have to continually test our assumptions. I interpret it this way: by all means, use logic to build your expectations, but continue to test against observations (I was about to write "reality", but that's a loaded word these days, too) and be aware of your assumptions. In science, I guess this would be finding the best current approximation to reality (here I'll use the word!) through testable hypotheses.

"The philosophy of experience is known as empiricism. Empiricism says that a concept is valid only if it is derived from, or is testable by, experience. The alternative theory is ‘rationalism’, the view that truth cannot be attained otherwise than by reasoning from self-evident first principles. The rationalist paradigm of knowledge is logic, the empiricist paradigm is science. Empirical knowledge is less certain than logic; it is tentative, responsive to new evidence and better research, always open to test. It is therefore the very embodiment of the spirit of preparedness to learn. Outside the formal disciplines of logic and mathematics there are no absolute certainties -- except of course in religion, which abounds in them, to the extent that people commit murder for their sake. But the experience of history always shows the danger of dogma. What additional bitterness of experience is needed before we learn to return dogma to the kennels of history whence it came?"

The reason of things : living with philosophy / AC Grayling. London: Phoenix, 2003. p.159