If you could teach the world just one thing about science, what would that thing be, and why? That is, what single scientific principle, concept or discovery do you wish everyone understood? And why is it so important? http://www.spiked-online.com/

The single principle is that there is really no such thing as "science"! Science is merely systematized, institutionalized common sense. The infant (human or other animal) learns from trial and error experience what to eat, avoid, mate with, etc. That learning from trial and error experience is already "science". Doomed is the forager who is not a "scientist" -- who does not learn to avoid the grains that have made him sick in the past, favour the terrains that have been plentiful, crack the nut before sinking his teeth into it. Doomed too is the organism that is indifferent to the outcome of his experiments: the one that keeps sticking his nose back into the fire. We humans have a second way of doing science, over and above individual trial-and-error (experimental) learning, guided by the error-correcting feedback arising from the consequences of our actions: We also have language, and can save one another a lot of risky and time-consuming experimentation by telling one another what's what. We can of course lie, or be in error. So our statements can be true or false. But the true ones ("Don't eat the mushrooms with the stripes: they will make you sick" or "Find a rock and smash the nut and you will find something good to eat inside") are our second way of doing science: By describing the outcomes of our experiments, and sharing them with others, to use, apply, test, build-upon.

Stevan Harnad