I couldn’t agree more with Helen Quinn that words should be chosen carefully when expressing the level of certainty regarding knowledge of physics. However, if the goal is to maximize the credibility of scientific communication, I think we should not overstate the case for that certainty.
Underlying our ability to obtain knowledge about the physical world are a few assumptions that must be taken as fundamental and are not actually tested by our experiments. One is the inductive principle that our observations can be generalized to obtain the laws of nature. A second assumption is that researchers’ memory and testimony are reliable. Quinn states a third: that physical laws are universal and immutable. The truth of these assumptions—or our ability to know their truth absolutely—has been questioned by various philosophers. 1 Many theologians would take issue with the last one. In fact, nonscientists could correctly label all three as beliefs, articles of faith held by those with a scientific mindset, in the same way that people hold beliefs in other areas of human thought.
Quinn’s statement that “we know that protons and neutrons are composed of quarks and gluons” is an example of wording that is too strong. How do we know there is an underlying reality to this theory? Or is it simply a mental model consistent with our experimental results?
Practically speaking, nonscientists’ judgments are influenced by conclusions presented in all of science, not just physics, even though we physicists may be tempted to think that our knowledge is more certain than, say, that of researchers in biology or medicine. When a person reads reports that red wine or coffee is good or bad for human health, that a flu pandemic is imminent, or that it is going to rain tomorrow, a certain amount of skepticism may be justified. Implying that results in physics can be known with absolute certainty opens up physicists for criticism as dogmatists and may lead to mistrust between scientists and the general public. Many readers of popular science are willing to accept research results if they are presented in a manner that does not encroach on their religious or ethical beliefs. To be credible, physicists need to make sure their conclusions are stated with the appropriate level of conviction.
