Why do scientists, whom we often call specialists today, think they are telling the truth when all too often they contradict each other?

Answer

Indeed, scientists sometimes seem to contradict each other in the media, I understand your reaction. The answer to your question lies in the fact that science is a process. It starts with a question, then scientists propose different possible answers, which are called “hypotheses” in science. Scientists then test the various hypotheses by conducting observations and experiments to prove or disprove the hypotheses. When in the end one hypothesis remains that cannot be disproved and for which there is a lot of evidence, it is generally accepted and is called a scientific theory. This is so-called “hard science”, knowledge that is accepted by all scientists and on which one can build. Examples are Newton’s theory of gravity or Darwin’s theory of evolution. Another example: three generations ago people did not know that smoking tobacco was dangerous. Only later did scientists find it abundantly clear that: 1) smoking leads to damage in the DNA of lung cells, 2) DNA damage can lead to cancer, and 3) there is a clear association between long-term smoking and risk of lung cancer. Now it belongs to the “hard science” that smoking can cause cancer.

But at an earlier stage of the scientific process, there is not yet sufficient evidence, and one could speak of “soft science”: there are still several hypotheses to answer a question, and there is not yet a generally accepted theory. In the example of cancer, it is not yet known with certainty whether, for example, the radiation from a mobile phone could cause cancer. There is currently insufficient evidence for it, so most scientists think not, but some believe they already have evidence and believe it could be dangerous. It will be several years before this relatively new technology will know whether it poses any health risks (and then it will be “hard science”).

New scientific knowledge does not appear out of thin air, it develops after a relatively lengthy process. Because scientific knowledge is acquired through this process of hypothesis formulation and testing, there is thus a phase in which uncertainties still exist and conflicting hypotheses can be promulgated.

When scientists give their opinion in the media on a question that still belongs to what I call “soft science”, they would better make it clear that there are several hypotheses and that the one they may be advocating is not the only one.