Advantages Context-independent, hence applicable

regardless of source, medium, location, affected interests (“risk science”)

Calculable, hence comparable and fungible (risk-benefit analysis)

Communicable, within limits, especially through comparisons (relative risks)

Disadvantages Same as above!!!

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Model uncertainty: right causal assumptions? Climate change is anthropogenic, not caused by

sunspots or random temperature fluctuations Rats are like humans in responses to toxicity

Parameter uncertainty: correct choice of parameters? Climate variation is related to carbon emissions from

car use, deforestation, volcanoes; offset by aerosols Measurement uncertainty: accurate, valid?

Role of instruments, simulations, “ground truthing” of satellite data, historical records, lay experience

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Actual (actuarial) risks: Based on reliable aggregate statistics

(e.g., common accidents, common causes of death)

Perceived risks: Relative ordering of risk as compared

with actual probabilitiesLay vs. expert risk perceptions:

Risks ranked differently across social groups

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Popular explanation: ignorance of facts, probabilities, science,

Psychological (experimental) explanations Exaggerated fear of unknown Fear of loss overrides hope of gain

Social explanations Historical experience of institutions Perceived lack of control Unattended ethical concerns (Quist/Chapela)

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What is problematic about defining risk as probability of harm X magnitude of harm? The problem of characterization▪ Models and their uncertainties

The problem of perception▪ Lay versus expert assessments (Note: not the

same as wrong vs. right!) The problem of politics▪ Differences in values, priorities, trust

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Conventional (linear) account Probability x magnitude of harm Hazard + exposure Impacts Characterization and communication

Socially embedded (recursive) account Risks arise within and from social practices Risks are framed by culture Risks are perceived in social and historical

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