Communicating uncertainty: managing the inherent probabilistic character of hazard estimates

Abstract A key aspect of ethics is the concept of responsible behaviour, that is, the attitude of correcting one's own actions based on the foreseen effects. In the case of Earth scientists, these actions mainly concern providing and communicating authoritative statements that are the basis of activities devoted to prevent possible losses. When deterministic statements are provided, science and scientists are imputable for any wrong action that relies on these statements. Probabilistic statements, instead, imply the possibility of alternative scenarios characterized by a degree of belief assessed based on the available knowledge. In this case, the lack of any definitive ‘truth’ requires the responsibility of a relevant decider to choose among several possibilities. Correctly communicating case by case the actual nature (deterministic or probabilistic) of the scientific statements becomes of paramount importance to manage effectively the relationship between the scientific community and society. The adoption of an epistemic view of probability and the use of clear decision-making tools may be of great help in providing a more effective basis for translating probabilistic statements into a comprehensible language and may also clarify the respective role of scientists and society in facing geological risks.