It is widely thought that ideal theories of justice should be specified assuming full compliance with the demands of justice. This is for two reasons. The first is that the justification of an ideal theory should bracket implementation concerns and that full compliance ensures the sought-after abstraction. The second is that an ideal theory should not concede to morally deficient conditions, in particular, to a lack of motivation to behave as justice requires; assuming full compliance ensures against such concessions. This dialogue shows that the assumption of full compliance can fulfill these tasks only under highly restrictive conditions. Put differently, I show how, except for an extreme case, the justification of ideal theories of justice always involves the assessment of their implementation in concessive background circumstances. Additionally, I show that ideal theories face a trilemma. I start by showing that "full compliance" is radically ambiguous regarding human motivations, which in turn threatens to make the requirements of ideal justice perniciously indeterminate. I then show that the options for avoiding this threat of indeterminacy pose a dilemma. The first horn says that indeterminacy can be avoided by arbitrarily restricting one's assumptions about human psychology; but this implies that the demands of ideal justice are based on assumptions that are not founded on any principled rationale. The second horn says that indeterminacy can be avoided by making extreme psychological assumptions; but, as I will show, this implies that ideally just societies have no need for institutions or social practices to enforce, and thus provide assurance of, full compliance with the demands of justice. Thus, ideal theories of justice face a trilemma: either their content is indeterminate, or their justification is arbitrary, or their demands are perniciously utopian.
David Wiens' research and teaching interests lie at the intersection of political philosophy, philosophy of social science, and political economy. His main project uses resources from formal choice theory to model core features of the arguments theorists give to justify normative political principles. This model yields insights regarding (among other things) the possibilities for coherent normative evaluations and the ways in which feasibility considerations constrain normative judgments. These insights motivate adoption of an approach to normative political theory that focuses on analyzing and overcoming institutional failures (as opposed to the conventional practice of analyzing institutional ideals). He's also interested in sorting out what we can learn about the nature and value of justice from formal models of collective choice, social bargaining, and institutional development.
Before arriving at UCSD, he was a Postdoctoral Research Fellow at the School of Philosophy at the Australian National University.