But it's a matter of the essential thing being the same only as far back as it really is the same. Sperms and eggs are not separate creatures; the newly concieved baby is. It's from conception forward that there's aren't essential biological differences. The genes are the same, ect, from then on. Not the case before conception, since combining and juggling genes is the whole point of sexual reproduction.
Once you allow the sequence to be aborted at any point -- you have the same ultimate consequences -- the lost to the world forever of a unique human potential. The only recourse is to force women to have babies as fast as they can for as long as they can. An absurd result.
Let's continue the reductio ad absurdum. This sequence you described continues after birth; it goes on to the person in question having children of his own and eventually dying of old age or some disease. So if "allow[ing] the sequence to be aborted at any point" is all the same, regardless whether you do it with a condom or by killing the "product of conception" in question, logically you must either permit murder, or require women to have as many babies as possible. QED?
Words is hard.
I'd rephrase this slightly differently.
Sperm and egg are separate. They have their own independent lifecycle. Left unkilled, they will die a natural death a few hours or days later, still as sperm or egg.
After conception, a fertilized egg (or embryo, or fetus, or baby) will also have an independent lifecycle. Left unkilled, it will also die a natural death many years later - as a man, or woman.
There will be unlimited points in this new lifecycle when this life may die without interference, or when an outside person may choose to end this new life. These points will not end after birth (as illness, accident, and murder cases demonstrate). But they certainly begin at the point of conception, when this new life takes shape.
Okay, work with me here. When a bullet hits someone in the head, that's attempted murder (or murder if it kills him.) Is it still attempted murder BEFORE the bullet reaches the head? Surely there is a difference between a bullet in flight and a bullet expending its kinetic energy inside soneone's noggin. Or further back still, when the weapon is aimed and the trigger pulled. Or further back yet, when the person's impulse is to kill. Well, there we have lost the trail -- we can't see into his mind -- but some people know their own minds -- "oh I would have killed him if ..."
Yeah, a unjoined sperm and egg are different than a joined egg and sperm -- but a launched sperm will potentially make it to the egg unless prohibited by, say, a condum. And a fertilzed egg will make it to a newborn baby unless prohibited, say, by RU486.
This is the problem with "potential" and "sequence interruption." Any waypoints are arbitrary.
This sequence you described continues after birth ... logically you must either permit murder
Quite so. In fact you have to forget sequence and potential, it is unenlightening.
Instead, the uniqueness of the human, that which makes a human a human, is not his genetic potential, not his gene code, it is his mind. And the mind doesn't develope right away. I can't tell you when the mind reaches the stage of a human, but it isn't when it is a small clump of cells right after conception.