Tolle Lege!.

I can't recommend this lecture highly enough. It is definitely on my short list for the best lecture (and book) I've ever listened to. I just read a very negative review in the Wall Street Journal for Weinberg's new book, "To Explain the World", which illustrates perfectly why this lecture is so great, by a reviewer who obviously never listened to this lecture. He attacks Weinberg for thinking Bacon was not influential, Descartes and Galileo were too Platonic and Plato was silly. After having listened to this lecture I realize how misinformed the reviewer really is, and how all those things are true and why.

Absolute Knowledge must be "universal, necessary, and certain". That gives the deductive systems. But, science is partly an application of logical truths to empirical facts. That will give us some problems. Such as, If it is a crow, it is black". As far as we know that is a true statement. Even the contra positive, "if it is not black, then it is not a crow". But, and here is the reason why deductive logic systems (mathematics, tautologies, or universal, necessary, and certain systems) can lead to absurdities is it used to be said that "all swans are white", guess what they found black swans in Australia. The premise must be true for the system to work, but cause and effect is always the particular based on observation, and one never knows the truth of a premise unless one makes the rules as in chess or in math but never from observations (swans can be black). "All living Pegasus are green" is absolutely true since when you assume a false premise anything that follows must be true. For a deductive system to be relevant to the real world there must be something from the real world to tie it to. The moment you do that you take the system out of the certain and put it into the probable. Revealed religions have this problem, but most believers never realize the problem for what it is. Once there is certainty (as in Christianity) there is nothing but sophistry and I can learn nothing from sophistry.

Once again, I can't recommend this lecture enough for people who want to understand our place in the universe.