 We would suggest yet another “evidentiary” approach to accommodating the conviction that every human being has full moral status, one that calls for the adoption of a strong, even “irrebuttable” presumption of full moral status for all human beings. This approach is based on the difficulty of assessing the cognitive potential of human beings, the powerful tendency to underestimate the capacity and potential of human beings with any degree of cognitive abnormality, and the terrible cost to individuals who warrant but are denied full moral status. This approach can be regarded as rule-consequentialist, in requiring that we sometimes disregard our case-specific judgment because of the high probability and substantial costs of error. But it may appeal to many who reject rule-consequentialism as a general approach. At the same time, this rationale for full moral status may seem uncomfortably grudging and contingent. It appears to imply that, with sufficiently accurate assessment tools and sufficiently reliable assessors, we could deny moral status to many human beings whom we now are constrained to treat as having it. Moreover, their exclusion would represent moral progress.