Human value: three possibilities

Princeton professor Robert P. George writes:

There are three positions that can be defended without quickly falling into logical inconsistency. The first is that human beings are in no morally relevant way different from other creatures and therefore have no special dignity. The second is that human beings have an inherent and equal dignity; each and every human being possesses it simply by virtue of his or her humanity. The third is that some, but not all, human beings have dignity; those who have it possess it by virtue of some quality or set of qualities that they happen to possess that other human beings do not possess (or do not yet possess, or no longer possess).

Anyone who believes that stepping on an ant is not a grave moral wrong but murdering your grandmother to prevent her spending down your inheritance is one, has already rejected the first position. Anyone who accepts the third position will, in fairly short order, find himself driven by the force of logical argumentation into the positions infamously defended by Peter Singer. Assuming one doesn't want to embrace Singerism [e.g., infanticide], that leaves the second position.

Given the established facts of embryology (that a distinct, living and whole human organism exists beginning at conception), the second position George notes above -- the equal dignity of all human beings -- entails the moral impermissibility of killing human embryos and fetuses by abortion or embryo-destructive research.