The preembryo as potential: a reply to John A. Robertson.

...In conclusion, let me agree with Robertson that reasonable persons may indeed disagree on concrete conclusions touching preembryo freezing, discard, research, and diagnosis. But it is one of the challenges to reasonable people to give reasons for their conclusions. When Robertson notes that preembryo research "has been found acceptable by most bodies that have examined the subject," he leaves unstated the fact that many of these bodies have not given reasons for their conclusions. This is especially true of the Warnock Committee. It is definitely not true of John Robertson. He has attempted to give analytic support for his rather permissive positions. I find this support too fragile for its assigned task, though I hasten to say that this does not mean that only a totally prohibitive position is defensible or is mine. Prima facie still means prima facie.