This is an attempt to argue that humans have the right to life from conception. I would call it the No Morally Relevant Difference argument. The idea is that once conception occurs, fetuses and born infants differ in four ways: born infants are larger in size, they are at a higher level of development, they have moved from the environment of the womb to the environment outside the womb, and they move from a greater degree of dependency to a lesser degree of dependency. However, all of these differences are a matter of degree, and none of them provides a basis for treating the fetus as lacking a right to life while affirming the born infant's right to life. Therefore, unless we want to draw the line on the basis of convenience, we have to draw the line at conception.
I don't know if this works or not. One commentator noted that at the beginning there is no brain activity and therefore, presumably, no sentience, and that should make a difference as to whether a fetus has the right to life.We should also be hearing music from that famous violinist right about now.
It is remarkable, in spite of the demographic tendency of pro-lifers to come primarily from conservative religions, and pro-choicers to come from religious liberals or secularists, the secular character of the central arguments in the abortion controversy.