This study examines the processes ofdecision-making used by intensive care(critical care) specialists. Ninety-ninespecialists completed a questionnaire involvingthree clinical cases, using a novel methodologyinvestigating the role of uncertainty andtemporal-related factors, and exploring a rangeof ethical issues. Validation and triangulationof the results was done via a comparison studywith a medically lay, but highly informed groupof 37 law students. For both study groups,constructing reasons for a decision was largelyan interpretative and imaginative exercise thatwent beyond the data (as presented), commonlyresulting in different reasons supporting (...) thesame conclusions and similar reasons supportingopposite conclusions. The skills of ethicalimagination and interpretation were related toan individual''s prior lived experience,construed in the broadest sense. Application ofthese skills of ethical imagination andinterpretation always occurred, to some degree,in a state of uncertainty and almost alwaysinvolved temporal relationships.Using these results, a theory of ethicaldecision-making is proffered. Three levels ortypes of reasoning processes may be present.Type I decision-making involves the applicationof rules, usually in a deductive fashion. TypeII decision-making is characterised by aprocess where a plurality of reasons arebalanced, weighed and sifted with each other.Type III decision-making is intimately linkedwith respondents lived experiences and `crafts''the content of type I and II reasoningprocesses, via the application of ethicalimagination and interpretation. Relationshipsbetween these three types of reasoningprocesses, and with narrative ethics, are alsodiscussed. (shrink)