Logic can often be reversed, but the effect does not precede the cause.

Thirty years ago, we used to ask: Can a computer simulate all processes of logic? The answer was yes, but the question was surely wrong. We should have asked: Can logic simulate all sequences of cause and effect? And the answer would have been no.

Life is opinion.

It is of first-class importance that our answer to the Riddle of the Sphinx should be in step with how we conduct our civilisation, and this should in turn be in step with the actual workings of living systems.

In the transmission of human culture, people always attempt to replicate, to pass on to the next generation the skills and values of the parents, but the attempt always fails because cultural transmission is geared to learning, not DNA.

A major difficulty is that the answer to the Riddle of the Sphinx is partly a product of the answers that we already have given to the riddle in its various forms.