Why would people be against abortion?

There’s no “cut off point” here. Something either contains human genes or it doesn’t. Something can either develop into a fetus or it can’t. They’re discrete rather than continuous differences.

Then change "cut-off" to "criteria", the point remains the same.

That makes all the difference. Criteria are needed in definitions to be able to meaningfully talk about anything. Cut-off points aren't.

Never understood why people are against abortion especially when it comes to strangers online. It doesnt affect you so why are you bothered about it. People will always make excuses like "dont have sex" or "its killing the baby" but i dont understand why some people act like a POTENTIAL life is more valuable than the mother - who is currently living a life.
People will always say stupid **** like "abortion is only okay if the girl got raped" but honestly i think thats just a stupid statement because a girl should be able to get an abortion because its her body? They have the right to control their bodies and its just annoying to see posts on social media with people spouting nonsense.
Only saying this because my friend thought she was pregnant and she was talking to her family that she will get an abortion. She's not pregnant but her whole family was against the idea but she was dead set on it. Again, why do people car, surely its better to support them? Abortion isnt exactly a walk in the park either.

There’s no “cut off point” here. Something either contains human genes or it doesn’t. Something can either develop into a fetus or it can’t. They’re discrete rather than continuous differences.

And? My question still remains. You have given criteria to define what makes something "human life". Why should we use that criteria, as opposed to some other criteria?

A fertilised egg can't develop into a fetus without a viable womb either.

I know that. What’s your point?

You don’t have to. You can call cats and bananas and all sorts things without human DNA “human life” if you want. But nobody will understand what you’re talking about.

So, by your own definitions, you wouldn't consider a fertilised egg a "human life", if it can't develop?

So, by your own definitions, you wouldn't consider a fertilised egg a "human life", if it can't develop?

But it can develop into a fetus. It just needs the right conditions. An unfertilised egg can’t.

Then what's the problem with abortion? Just define embryos and fetuses as not "human life".

Yes it can, if it gets the additional "right condition" of coming into contact with viable sperm.

What’s the problem with killing the African bushman? What’s the problem with killing anybody? Just define them as “not human life”.

That's exactly what I'm saying.

No, I'm not "being silly for arguments sake"; I'm pointing out that if you're claiming that they have different value, then you need to be able to provide an iron-clad justification for that. It's not something that can just be taken as given in a debate on abortion when it's the very crux of what both sides disagree on. One doesn't win a debate on a highly controversial issue simply by saying "oh well any sensible person would agree with me".

Have you considered the implications of the idea that it's fine to kill a bunch of cells which can't think or feel (at present)? For example, the fact that this would also make it fine to kill someone who is temporarily under general anaesthetic or in a coma? These sorts of examples tell me that the ability to think and feel aren't usually considered to be requirements for someone to have the right to survive.

And indeed, that's if we're even certain at all that the unborn child / foetus can't think or feel. As recently as the 1980's we also thought that babies couldn't feel pain and routinely performed surgery on them with no anaesthetic; we now know what a terrible idea that was. Furthermore, brain and nervous activity becomes detectable after only 6 weeks of gestation, which is already far earlier than the 24 week abortion limit.

But it can develop into a fetus. It just needs the right conditions. An unfertilised egg can’t.

It isn't needed. If we already agree that in general it is wrong to kill other members of the human species, it is the exception that requires justification rather than the rule. The burden of proof lies with those saying it is morally acceptable to kill them.

You tell me, it's your argument being debated. You haven't given any reason why "human life" should be defined as anything after fertilisation, it could easily be defined otherwise.