Belief and Knowledge

Helen Quinn is a particle physicists at the Stanford Linear Accelerator Center and a former president of the American Physical Society and also has been involved in science education and the public understanding of science. Quinn has written an extremely important article that was published a few years ago in the journal Physics Today called Belief and knowledge—a plea about language, dealing with how well-defined scientific concepts are sometimes misunderstood and even abused by the public, which is often incredibly frustrating.

Quinn starts with a personal anecdote: as her husband where describing the topic of his thesis to a layperson, which was using a coincidence set up for to see that two particles detected simultaneously where most likely coming from the same event.

I remember the puzzlement of a friend as my husband described his thesis research—a coincidence experiment. His listener stopped listening; she was thinking about why anyone would try to measure coincidences. I pointed out that the word “coincident” simply means “occurring at the same time.” The experiment used its precise timing to ensure that two particles detected at the same time had a very high probability of coming from the same source event. Thus the term coincidence was used in a sense opposite to the everyday meaning, where a coincidence is two uncorrelated events that come together. Words shift their meaning; each community develops its own usage. That change in meaning leads to miscommunication.

Quinn points out that this problem does not just arise with the term coincident, but with other terms, such as theory and energy and explains how this can lead to misunderstanding of science.

A few words in elementary physics— force, work, momentum, and energy—have carefully defined physics meanings. Their much broader everyday usage causes students a great deal of confusion until they learn the precise physics concepts. Rather than belabor such cases, I will focus on some words that are, I think, the root of considerable public misunderstanding of science: belief, hypothesis, theory, and knowledge. […] We need to be much more careful how and when we use them in talking to the public.

Quinn then goes on to look at these concepts in turn, contrasting their scientific definition with their everyday usage, starting with “believe”.

What do we mean by “scientists believe that . . .”? Typically it is something like “Most scientists agree that the preponderance of the evidence favors the interpretation that . . ., and furthermore, there is no evidence that directly contradicts that interpretation.” Clumsy language perhaps, but it would behoove us to say something like it more often. If we need a shorthand version, we can replace it by “Scientific evidence supports the conclusion that . . ..” Sometimes we should just say “We know that . . ..” In other words, we need to articulate more precisely the state of our knowledge—its authority or uncertainty.

I have noticed this issue as well and because of it, I have stopped using terms like “believe”, and instead used terms like “think”, “suggest”, “accept”, “concluded”, “have an evidence-based position that” and so on. Perhaps a bit convoluted, but it gets the job done without too many misunderstandings. Quinn comes to a similar conclusion, advocating not even using the term at all anymore.

If we set up science as just another belief system, we weaken its authority and dilute the power of our knowledge. If our “I believe” is heard in the sense of uncertainty, that weakens the strength of our assertion even more. We could, and I think should, excise the word “believe” from our vocabulary when talking about science.

It is not just honest mistakes being made of course. Sometimes, anti-scientific forces intentionally abuse scientific concepts, like energy or theory for their own malevolent goals. One such example is “theory”.

We also use “theory” in a way that is far from the everyday usage (where a theory is pretty much a hunch), particularly when we talk of “the theory of . . .”; examples are relativity, electromagnetism, evolution, plate tectonics, the standard model of particle physics. […] These theories are far from guesses; they will survive no matter what new evidence is accumulated. They are complex constructs that incorporate and explain a significant body of evidence. They have demonstrated predictive power as well as descriptive power.

In other words, scientific theories are not merely speculative guesses, but rather well-supported explanations to some part of the natural world that can include facts, laws, inferences and tested hypothesis (to paraphrase the definition given by the National Academies of Science). If this itself is not a testament to the powerful reasoning performed by Quinn, read the following scolding criticisms about lazy science-writers.

The science press and scientists themselves do science a disservice when they seek to dramatize a discovery by emphasizing that it discredits a previous theory. Such coverage typically does not discuss whether the earlier theory was tentative or whether the new result modifies a well-established but incomplete theory. This dramatization feeds the popular image that all scientific knowledge is tentative. Much is tentative, but much is well understood and unlikely to be discredite

So Quinn concludes that scientists need to be better at conveying the tentative nature of science, but also that the most evidence-based models science has are unlikely to be completely discredited, although modifications will surely be done.