The objective (or "deeds") theory of justification has been attacked on the ground that one can never know for sure whether the circumstances for justification actually exist. One can only speculate as to whether the conditions exist. This is true not only for the actor at the time of the conduct for which a justification is sought but can also be true for the adjudicator after all available evidence has been gathered. The attack contains a useful insight about the nature of justifying circumstances: they necessarily contain some degree of unavoidable uncertainty. But it does not follow from this insight that justification defenses must necessarily be subjective in their formulation or conceptualized as based upon a "reasons" theory. This brief essay explains why this is so and what the "inevitably speculative" insight tells us about the objective theory of justification. Available for download at http://ssrn.com/abstract=969820
Robinson, Paul H., "Justification Defenses in Situations of Unavoidable Uncertainty: A Reply to Professor Ferzan" (2005). Faculty Scholarship at Penn Law. 142.