Is an embryo a person 2 – Twinning

One argument commonly put forward for why the embryo is not a human in the first 14 days or so of life, before implantation, is that it may yet divide into twins. If it can become two individuals, the logic goes, how can we say it is now a person? It must be in a pre-person state until it becomes two separate people.

Twinning is basically a cloning process, or a form of asexual reproduction. The one embryo splits into two pieces, which each grow into identical twins.

If we consider this from a purely atheistic perspective, the argument rapidly falls apart. Just because something may later become two individuals doesn’t mean it is not an individual before then.

If a bacterium divides to produce two identical clones, does that mean it was not an individual bacterium before the cloning? Of course not.

If the technology ever becomes available to clone a human adult (some claim it has already been done), a human adult could later become two humans. Does this mean the adult was not a human before the cloning?

The embryo is one human. If at some later point it can become two humans, that does not detract at all from the fact that it is already human. It only means that by killing it you have cut off the potential for two lives rather than only one – which is twice as bad.

Now if we add the Christian perspective, that humans are not only physical but also have a soul, you may be able to say the embryo is not human before it divided because the individual twins were not given souls until they separated.

But how do you know? This is pure speculation. God may do that, or He may give one soul at conception and a second one when twinning occurs, or (knowing twinning will occur) he may give both souls from the start… The Bible never says. We can speculate for ever but will never reach an answer. It is best to forget this line of reasoning and focus on the physical.

So whether you are atheist or Christian, the twinning argument holds no water. And anyway, most embryos don’t twin – how many identical twins do you know?

For a far more detailed refutation of the twinning argument, check out this excellent article by Alexander Pruss of Baylor University (hat tip MandM). Matt’s response is here, but he does not appear to really counter what Pruss says, just disputes some minor points.

I have discussed other issues around abortion in these posts.