Scientific uncertainty

When we look to science to answer questions about the world around us, we often expect those answers to be certain. However, uncertainty is a normal part of science. This can seem very frustrating when we want to know a definitive answer about, say, which course of treatment we should take, whether our favourite food is healthy for us or not, or whether legislation should be brought in for public health reasons.

However, just because science does not know everything about a particular topic that does not mean that it does not know anything. Every piece of scientific research makes up a tiny part of a wider puzzle of knowledge on a topic. The core value underpinning science is the idea of being open to the possibility of new knowledge or information. This means that scientists often express a small degree of uncertainty, even in cases where the vast majority of evidence points to one conclusion. Another way of saying this is that scientists are actively focused on what we do not know, but most people who want to use scientific evidence are more interested in what we do know. Unfortunately, some people, particularly those with vested interests, use scientific uncertainty to depict topics as more contested than they are in reality. For example, according to Sense about Science’s guide Making Sense of Uncertainty:

Researchers use uncertainty to express how confident they are about results, to indicate what scientists don’t yet know, or to characterise information that is by nature never black and white. But saying that something is ‘uncertain’ in everyday language has a negative connotation. When a researcher says ‘the predictions we made on the basis of our research have a margin of uncertainty’, they mean they are very confident that the outcome will fall within the predicted range. But a commentator is likely to understand from this ‘the piece of research is unreliable’. [page 5]

For example, you may heard it said that something is ‘just a theory’, however, in science, the term theory means something different to what it may do in every day conversation. A scientific theory (such as the theory that infectious diseases come from germs) is not just a guess, it is a well supported understanding based on the highest quality of available evidence. If an idea about the world was not yet backed up by fact, it would be called a hypothesis.

For more information on scientific uncertainty, we recommend Sense about Science's Making Sense of Uncertainty: Why uncertainty is a part of science.