From "A 'Breakthrough' in the Stem Cell Debate" by Michael Kinsley:

If you wish to believe that every fertilized egg is a human being with full human rights, that is your privilege. I disagree, which makes it a controversy. If I felt you were serious, we would have a quandary as well. But there’s no quandary because you’re not serious. Your actions are too different from your words. You are doing absolutely nothing about the millions of fertilized eggs that are destroyed naturally every year (in miscarriages so early that the potential mother is not even aware of them), or the thousands that are produced and unused by fertility clinics going about their normal work (which are either discarded or pointlessly frozen in the hope of some miraculous ethical breakthrough).

(Thanks, Jana)