In Popper's description of the world, if we are rational, we will base our decisions on truth, which is another way of saying we will base them on the best of our knowledge. Truth, in the scientific sense, is not absolute but that which corresponds to the facts, and of course, we never have all the facts.
How long is a piece of string?
Magee uses the example of measurement to demonstrate Popper's view of scientific truth. if you think about it, we can never obtain an exact measurement of the length of a piece of string. With more and more precise equipment we can reduce our uncertainty to 1 cm, 1 mm, 0.1 mm etc but an exact measurement is a concept, it can never be physically realized because we can always improve our accuracy.
Even though exact measurement is unattainable, we can still make great practical use of both measurement and accuracy of measurement. Our aim in accurately measuring the length of a piece of sting, just as in the scientific method, is to approach the truth ever more closely while accepting that we can never reach it. Alternatively, we can just say the length of a piece of string is twice half it's length, which is exact but does nothing to enhance our understanding of it's length.
Newton's universe
According to Magee, the clearest support for Popper's view of science comes from the story of Newton and Einstein's contributions to physics. Newton was clearly a genius and the impact that his theories had on science are hard to overstate. Mankind applied them to diverse fields and made huge technological strides. For hundreds of years, observation after observation confirmed their accuracy. In the classical description of the scientific method they were indisputable laws, scientific fact, ultimate truth.
Along came Einstein
Then, out of the blue, or out of the German city of Ulm, along came Einstein and shattered the very foundations of the Newtonian universe. This was a black swan event.
While Newton's theories appeared to be beyond doubt, Einstein showed that in some circumstances they didn't hold, just as water doesn't boil at 100 degrees centigrade on the top of Everest. What resulted was a much richer theory, one which just like Newton's, opened up a whole new world of possibilities.
This, argued Popper, is a perfect demonstration of how science should proceed. If we had clung to Newton's theories with religious fervor, we would never have discovered the riches of Einstein's theories. There is a delicate balance here, the rational approach to science is to proceed with the best theories we have as if they were absolute truths while remaining open to the possibility of a black swan or an Einstein appearing on the horizon.
I dreamed a dream
This doesn't mean we can rationally reject inconvenient scientific evidence on the basis that the evidence is uncertain (climate change comes to mind). We must first develop richer theories that are less uncertain and more fully describe our observations of nature.
In a similar vein, Popper's description of scientific truth doesn't advocate dreaming up random esoteric descriptions of nature and then arguing that since science is uncertain these baseless descriptions may just as well be true.
Fascinatingly, Einstein's theory of relativity did in fact spring from a random esoteric dream, but when he woke up he expended a great deal of effort using his creative insight to develop a rigorous and testable theory. The lesson, don't stop dreaming but remember to wake up afterwards!
Trust and openness
The purpose of science is to provide us with the truth to the best of our knowledge by applying rigorous tests. Einstein's theories only superseded Newton's after clear and widespread scientific demonstrations of their accuracy, not after a conversation in the pub or a few comments in a forum.
We shouldn't discount these types of encounters entirely however. In fact, Blog posts themselves are not too dissimilar from conversations in the pub. Such encounters may have value in themselves through planting the seeds of future new discoveries or helping to clarify thinking processes. Ultimately though, the scientist must find that delicate balance between trust in the old and openness to the new.
The series 'Right and Popper' is based on the summary of Popper's philosophy written by Bryan Magee. The introductory post in the series can be read here.
Image: Ruth Orkin/Hulton Archive/Getty Images
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