I don't think the 9/11 attacks taught us anything we didn't already know about religion. It has long been obvious - even to the deeply religious - that religious fanaticism is an extremely dangerous deranger of otherwise sane and goodhearted people.

True, you don't have to be religious to be crazy, but it helps. Indeed, if you are religious, you don't have to be crazy in the medically certifiable sense in order to do massively crazy things.

The juvenile sea squirt wanders through the sea searching for a suitable rock or hunk of coral to cling to and make its home for life. For this task, it has a rudimentary nervous system. When it finds its spot and takes root, it doesn't need its brain anymore so it eats it!

There may be things that are completely unknowable to us, so we must be careful not to treat the limits of our knowledge as sure guides to the limit of what there is.

Up till now, we can suppose, nervous systems solved the 'Now what do I do?' problem by a relatively simple balancing act between a strictly limited repertoire of actions - if not the famous four F's (fight, flee, feed, or mate), then a modest elaboration of them.

Some of the greatest, most revolutionary advances in science have been given their initial expression in attractively modest terms, with no fanfare.

I am a philosopher, not a scientist, and we philosophers are better at questions than answers.