But Steve, that's not the only, or even the main way people act. Science is about things that are known unambiguously (leaving aside the usual caveats in the interests of simplicity.) So is checking your Sainsbury's bill.

But actually the vast majority of your decision making is based on judgements without adequate evidence. Second by second while you drive you are making assumptions about what all the cars and pedestrians nearby are about to do: it is all based on assumption not evidence. Holiday planning, investments and loans, travel arrangements and expected time of arrival, the list goes on for ever.

Nor can we can avoid this using probability - since we are dealing with individual events, not statistics. It matters not that probability of a person stepping into the road without looking is X; all that matters is whether that person there is about to, which is not statistical in nature. The probability of horses wandering over the M25 on a typical journey must be extremely low, but it still happened to me a few months ago.

So all our thinking is sometimes evidence based, but sometimes not. And, to coin a mischievous phrase, it is the Scientific Delusion to think otherwise.