Lines of reasoning

1. Lines of reasoning • Direct empirical: direct observation of effects under the conditions of interest • Semi-empirical: observation of effects at exposures higher than those of interest • Theory-based: an etiologic theory suggesting an agent plays a causal role in an adverse effect • Empirical correlation: observation of an event that generally correlates with an adverse effect • Existential insight: expert judgment that an agent will cause an adverse effect

2. Our general task: Find a policy that produces reasonable confidence that the majority of the exposed population will have an acceptable risk.

3. Our more technical task: Find a policy that produces a confidence of no less than X% (e.g. 95%) that the exposed population will contain no more than Y% of people (e.g. 10%) with a risk greater than Z (e.g. 10-4).

4. What could be reasonable confidence? Not too little; not excessive; rationalBertrand Russell: Rationality is the selection of apt means for the highest ends

5. Forming rational beliefs Question: What ways of forming beliefs about risk would provide an “apt” means for producing “reasonable” confidence that people are protected against unacceptable risk?Claim: This is related in some way to the idea of “sound science”, with appropriate caveats and cautions.

6. Desiderata of Rationality Conceptual Logical Valuational Methodological Ontological Practical Epistemological

7. The classical school of rationality • Formal rules of reasoning • These are defined clearly • These are agreed upon by all participants • Rules are applied universally • All rational individuals reach the same conclusions

8. Bernstein and dialogical rationality “…stresses the character of this rationality in which there is choice, deliberation, interpretation, judicious weighing and application of universal criteria, and even rational disagreement about which criteria are relevant and most important.”