Frank Beckwith wrote a concise argument against abortion, and for the intrinsic value of all human beings regardless of size, location, level of development, or degree of dependency that I wanted to share with you:

The unborn—from zygote to blastocyst to embryo to fetus—is the same being, the same substance, that develops into an adult.  The actualization of a human being’s potential, e.g. her “human” appearance and the exercise of her rational and moral powers as an adult (which abortion-choice advocates argue determine the unborn’s intrinsic value), is merely the public presentation of functions latent in every human substance from the moment it is brought into being.  A human may lose and regain those functions throughout her life, but the substance remains the same being.

Moreover, if one’s value is conditioned on certain accidental properties then the human equality presupposed by our legal institutions and our form of government…is a fiction.  In that case, there is no principled basis for rejecting the notion that human rights ought to be distributed to individuals on the basis of native intellectual abilities or other value-giving properties, such as rationality and self-awareness.  One can only reject this notion by affirming that human beings are intrinsically valuable because they possess a particular nature from the moment they come into existence.  That is to say, what a human being is, and not what she does, makes her a subject of rights.[1]

[1]Francis Beckwith, “Gimme That Ol’ Time Separation: A Review Essay, Philip Hamburger Separation of Church and State.  Chapman Law Review, vol. 8:309, p. 324.