All knowledge is provisional, subject to revision in the light of new information. Knowledge is probabilistic. Some beliefs might be assigned infinitesimal probabilities – creationism and intelligent design perhaps – but all probabilities must be treated as revisable in the light of new evidence. Where knowledge (belief) relates to potential future harms or benefits, as it usually does in situations where science communication is seen as problematic or contentious, the issue can be framed as one of risk communication.

What is risk?

There are many ways in which one can categorize problems of risk and its management. Typing the single word ‘risk’ into Google produces hundreds of millions of hits. One need sample only a small fraction in order to discover unnecessary and often acrimonious arguments caused by people using the same word to refer to different things and shouting past each other. Figure 6.1 proffers a typology that has proved helpful in clearing away some unnecessary arguments.