Empiricism and positivism share the common view that scientific knowledge should in some way be derived from the facts arrived at by observation. - Alan Chalmers

The greater the number of conjectured theories that are confronted by the realities of the world, and the more speculative those conjectures are, the greater will be the chances of major advances in science.

It should be no news to anyone that the perceptual judgements of individuals can be unreliable for a range of reasons. The challenge, in science, is to arrange the observable situation in such a way that the reliance on such judgements is minimised if not eliminated.

Establishing by observation that there is just one black swan falsifies "all swans are white". This is an unexceptional and undeniable point. However, using it as grounds to support a falsificationist philosophy of science is not as straightforward as it might seem.