One side is convinced that a human life starts at the conception. And if you think that, it is very simple: Abortion is taking a human life, i.e., killing a person. Then nothing else matters. We can bring up all social, economic, feminist, psychological, health, etc. arguments in the world, all in vain. We all agree that we don't go around and kill people, so if you think that life starts at the conception, there's nothing more to argue about.
So in this case, we disagree only about meaning. The only way to have fruitful discussion would be to talk about what we mean by a human life. Then I'm not sure that is possible when one side's main argument is "the Bible says so". But there's nothing inconsistent or contradictory that could be resolved between the premises "a human life starts at conception" and "taking a human life is always wrong", and the conclusion "abortion is wrong".
Well, except for the police.
(Flippant comment, but the number of people who think abortion should be illegal under all circumstances but also that the police should never face any consequences for killing someone, no matter how gratuitously, is astonishing)
It doesn't make sense to dismiss an argument as merely semantic if you are talking about something more than just arbitrary definitions. In many cases, pro- and anti-abortion people have a genuine disagreement about the point at which life begins. This isn't merely a disagreement about how to define a particular word. You can, if you want to, characterize it as a dispute about what it 'means' for something to be alive, but that's a much deeper issue than a mere semantic quibble. (The debate can't, for example, be resolved by introducing two new terms alive* and alive†, with both sides of the debate agreeing that a foetus is alive* but not alive†.)
Yes, the different sides have a genuine disagreement about the point at which life begins, but that is because they mean different things when they say that something is alive.
So this discussion is becomming a bit too meta, but now we are discussing meaning of the term semantics. Considering that the author himself took up the discussion about abortion as an example of something that is "purely a semantic one", I'm convinced that he meant the same thing as I do when he used the term semantic.
So the author does seem to be saying that the whole abortion debate is purely a debate over arbitrary definitions, not merely that it's important to clear up semantic issues before getting into the meat of the debate.
If the issue were purely semantic, it would be possible to resolve the debate simply by introducing unambigious terminology agreed on by both sides (e.g. using 'alive*' and 'alive†' rather than 'alive'). If this doesn't satisfy both sides, then they aren't really disagreeing over the meaning of the word 'life', they're disagreeing over the nature or essence of life itself. Informally we can say that they disagree over what it means to be alive. But philosophically it's important to be clear that this isn't just a semantic issue about the meaning of a particular word.
Another way to bring this out is to think cross-linguistically. Do we really have to have the abortion debate over again for every one of the world's ~6500 languages and their corresponding words for 'life'? I think not, because at heart the debate isn't a debate over word meaning.
Which is quite much exactly what I said.
That a definition is arbitrary doesn't mean that it is unimportant. If I use one arbitrary definition, and you another one, we won't have any meaningful discussion. Sometimes this can be resolved, when the definitions themselves aren't the central issue and we can agree about at least some provisional defintions. Sometimes the definition itself is the central issue, and can't be resolved. Like when we disagree about the meaning of the term life. In this case, any provisional definitions won't help.
> then they aren't really disagreeing over the meaning of the word 'life', they're disagreeing over the nature or essence of life itself
Those two things are the the same. What is the meaning of a word other than the "nature or essense" of the thing it references?
This is actually a vexed question in linguistics and the philosophy of language. I don’t want to get into it here, but the answer to your question is not in any way uncontroversial or obvious.
For me the idea that the root of the abortion debate is a disagreement over an arbitrary definition doesn’t compute, for the reasons I already gave. (Why not just introduce new words with commonly agreed definitions and be done with it?) But that discussion seems to be going round and round in circles.
life_prolife = life begins at the conception.
life_prochoice = life begins at week 20 of the pregnancy (as an overly simplified example for the sake of argument).
Pro life: it is wrong to kill anything that has life_prolife.
Pro choice: no, it is only wrong to kill anything that has life_prochoice. It is, at least under some circumstances, ok to kill something that has life_prolife but not life_prochoice.
So of course we haven't resolved anything (which I think is your point). Rather, we have moved the discussion to which definition is the one that is relevant to use when we discuss the sanctity of life. And that is a discussion about semantics.
Perhaps the broader issue here is that everyone loves to tell themselves they're leaving a community because they're too good for it, rather than just admitting that's it's become bad for their mental health to get involved in frequent anonymous arguments on the internet.