by Federico N. Fernández
In the book Darwin’s legacy, philosopher John Dupré makes an interesting remark: “I… do maintain that science can accumulate enough evidence for its claims to make them almost  impossible to reject, and I believe that certain broad evolutionary theses have earned this level of credibility.” Due to the ‘almost’, this is a somewhat watered down version of good old epistemological justificationism.
In fact, we are still used to believing that science provides us with true and justified knowledge. This means that accepted scientific theories are not only true, but we have also a method to show that they are true. And we are still used to believing that this epistemological guarantee is induction. In fact, in its stronger version, induction is both method and justification. It is the method because science supposedly operates inductively –via unbiased observation of nature in order to infer certain regularities. And it is scientific justification because these observations give empirical support to our proven theories.
In his 1934 Logic of scientific discovery Popper developed a revolutionary alternative for the methodology and philosophy of sciences. Induction, according to Popper, played no role in science. Scientists start with problems which they want to solve. Observation, thus, happens always from a certain point of view. In the first class of the semester, Popper asked his students at the London School of Economics to “make observations and take notes.” His students were confused since they did not know what to observe. Popper used this to exemplify his idea that observation is always guided by an underlying theory. Moreover, induction said Popper, can never prove our theories. How many positive cases can definitely prove a scientific universal law? How many white swans can prove to us that all swans are white? Under the false belief that science could not be empirical unless it is inductive, many have neglected the logical problem of induction or even fallen into irrationalism.
Popper’s solution to this problem is that science can still be rational and empirical as long as it is critical. Experimentation can play an important role in science, but it is no longer a positive one. Empirical tests can help us to discard false theories. Thus, we test our theories against reality not to prove them, but to be able to refute the ones that are wrong. Popper said that the scientific method was the method of conjectures and refutations. Scientists propose bold theories and then try to test them with the most rigorous experiments. The richest theories are the ones with predictions that rule out the most possible states of the world. In this way, they face a bigger challenge of being falsified. The rational attitude, for Popper, is to go look for the black swan. Our knowledge grows not when we find positive cases for our existing theories but when we find negative cases that contradict them. What makes science empirical is falsification. What makes our knowledge grow is that when theories are falsified, we have to replace them with new theories that have more empirical content. This means that the new theories have to explain all that the older theory did plus the anomalies that the falsified theory could not explain. Popper thought that this process of conjectures and refutations got us closer to the truth, but was itself never ending.
Upon closer inspection, Dupré’s quotation sounded very reasonable. However, its implications –from a Popperian point of view– are dramatic. Ultimately, it is not rational to maintain that our theories, however fruitful they have been, can be justified… or “almost” justified. This constitutes a leap of faith –not good science. Furthermore, Popper even said that the moment a scientist thinks that her theory is justified and criticism and tests are no longer needed, she leaves the game of science.
An open project
My friend Mark Notturno worked with Popper in the last years of his life. Popper told him that his philosophy could be summed up with these words: “I may be wrong and you may be right, and by an effort, we may get nearer to the truth.”
Here, here, and in the present article we have reviewed some questionable instances of the political process, the epistemic status of theories and the social perception of science. Many other things could be added to our list, from political correctness as source of new taboos, to the growth of fanaticism right in heart of Europe. In the light of these problems and misconceptions, a rational, dialogical, nonconformist and antiauthoritarian approach like Popper’s seems worthy of being revisited.
 Italics are mine.