The problem with being a gradualist with regards to the right to life

Will Saletan, a pro-choicer who recognizes that the unborn are living human beings, writes the following in response to a column by Yuval Levin.

I cringe at this interpretation of the Declaration. Levin believes that equality means a five-day-old embryo has the same right to life as a 5-year-old girl. I just can't buy that. I'm a gradualist. I value the five-day-old embryo because it's on its way to becoming the 5-year-old girl. But it's not there yet. It hasn't acquired the sentience and cognition that characterize a full-fledged human being.

What about newborns? Do they not have the same right to life as a 5-year-old girl because they haven’t acquired the sentience and cognition which characterize a full-fledged human being?

The problem with being a gradualist with regards to whether human beings should have the right to life (notice how it would no longer be “inalienable”) is that the qualities so admired by many gradualists (sentience, cognition, etc.) is that these qualities don’t emerge until after birth (should it be legal to kill newborns?), they grow gradually throughout life (should humans with a greater quantity of these qualities have a greater right to life?) and then they typically wane towards the end of life (should humans who lose these qualities also lose their right to life?).

"Full-fledged" human beings aren't characterized by sentience and cognition. Those are natural capacities (like walking and talking) which many human beings currently possess while there are other full-fledged humans who haven't yet reached the stage of development where they will possess them and there are other full-fledged human beings who have lost those capacities and other full-fledged human beings who will never possess them.

Then Saletan ends with something which makes me wonder if he truly understand the feelings of prolifers.

Slippery slopes run both ways. Let's call that Human Nature's second law. If we don't draw moral lines against the exploitation of embryos, we may end up obliterating respect for human life generally. But if we're so afraid of that prospect that we refuse to draw lines permitting the use of any embryos under any conditions, we may end up obliterating the moral difference between embryos and full-grown people. Liberals should think seriously about the first scenario. Conservatives should think just as seriously about the second.

Prolifers don't accept that there is a moral difference between embryos and adults. That's the basis of the prolife position - that all human beings regardless of size, level of development, environment and degree of dependency have the right to life. It's not a slippery slope for us to protect human embryos. That's our goal.