How do you reason that people have the (presumably absolute) right to alter than bodies however they please? How do you justify that claim? It makes very specific assumptions which are very problematic. For example, do you have the right to lobotomize a perfectly healthy brain? It is immoral? Can you say you have the right to do something immoral? How about altering your uterus during pregnancy to prevent nutrients from feeding the child?
I think it's pretty obvious that right implies morally acceptability. You can't claim to have a right to something evil. (The reverse is not true. It is morally acceptable to own a Tesla, but you don't have the right to one.) Alterations can be harmful and any harm that is not a justifiable side effect is by definition immoral. That it's your body does not somehow negate the immorality of self-harm. Indeed, direct self-harm is even worse morally than harm of others because it is in direct opposition to one's own good (arguably, harm of others is also a form of self-harm, specifically harm of one's character and will and habitus, of one's intellect because of the harm of one's reasoning faculties it entails, and harm of the common good). So you cannot say you have the right to self-harm. This is just a strange consequence of the incoherent ideology of absolute autonomy.
Now, if you have, say, a defect in your body that is preventing the proper functioning of your body, then we may correct this defect through intervention. This is restorative, that is, it seeks to restore the function due to the body by virtue of how it ought to function. This is the basis of medicine.
Another false view that can nudge people toward the view that any modification is acceptable is metaphysical materialism, also incoherent. In that case, crude metaphors between artifacts and living things are elevated to the status of the truth and since it doesn't matter what we do to an artifact per se. We can modify a computer any way we wish because there is no fact of the matter about what a computer is or how it should be apart from human intent. It is just a collection of things arranged in a particular way incidentally that puts them in a series of incidental causal relations, but there is no inherent tendency for these things to exist in these relations and no accounting for one in terms of the others except through the lens of human intent. Living things aren't like that.
If you don't have the right to your own body, then there aren't rights. It's the axiom.
I'm in favor of drug use (at least almost all), tattoos, body modifications, trying experimental medicine, everything that affects your body. I can see drawing the line at "doing this thing could become a contagion so you can only do it in BSL-4 isolation". But it's your body, your life, you want to spend it stoned or a voluntary amputee or whatever so long as don't take from me, then you should be free to do so.
> I think it's pretty obvious that right implies morally acceptability. You can't claim to have a right to something evil.
I think it's pretty obvious that right does NOT imply moral acceptability, and that you can have a right to something evil. In our societies, we have a great deal of disagreement about what things are morally acceptable/permissible. For a good liberal society, we may allow many things that we think are actually immoral, even evil. You need look no further than, say, the religious arena (including atheists) for such disagreement. People disagree about the moral acceptability of worshiping different gods (or about worshiping any 'gods'), calling someone an asshole, teaching your children one thing or another about sex, about engaging in particular sexual acts, about giving charity (or refraining from giving charity) to certain causes, and so on.
We grant people rights to do certain things (and I'm glad we do), but that does not entail that those things are therefore morally acceptable/permissible. You have a right to do them, but maybe you ought not.
> "How do you reason that people have the (presumably absolute) right to alter than bodies however they please? How do you justify that claim?"
If you couldn't gouge out your right eye and cast it from thee (Matthew 5:29), would you still have freedom of religion?
> "So you cannot say you have the right to self-harm. Now, if you have, say, a defect in your body that is preventing the proper functioning of your body, then we may correct this defect through intervention. This is restorative, that is, it seeks to restore the function due to the body by virtue of how it ought to function. This is the basis of medicine."
What about vaccination and such where the intent is to cause a small amount of harm now, to prevent a problem you don't have - and may have never faced in any future. This is not restoring a defect, it's augmentative and preventative. Do you not have the right to cause that small harm? And yet that's in opposition to your "direct self-harm is even worse morally than harm of others because it is in direct opposition to one's own good". It's in alignment with one's own good. So, for example, are the torn muscle fibres when weight lifting, or the buildup of lactic acid causing muscle burn when running, or working through the night with no sleep in an emergency.
Less seriously, piercings for jewellery are self-harm and for one's greater happiness in appearance. Do people have no right to wear small pointy uncomfortable high-heel shoes? Is that immoral?
> "I think it's pretty obvious that right implies morally acceptability."
I think it's pretty obvious that there isn't a single "moral acceptability" which everyone agrees on. For example some have the right to eat animals and others consider that morally inacceptable. Some US states have different rules on public nudity than others, and some groups of people have different opinions on the morality of it.
> "You can't claim to have a right to something evil"
Not sure I follow this one; you can't really have a right to murder others, but in the sense of self-harm is it really "evil" to hurt yourself? What is evil and also doesn't involve harm to anyone else?
> "For example, do you have the right to lobotomize a perfectly healthy brain?"
One could argue whether a "perfectly healthy" brain would choose to lobotomize itself, but let's say it does - why do you say that's "very problematic"? The main objection I have - assuming the person is considered sane and healthy - is who is going to pay for the care afterwards, i.e. the harm rolls over onto others and is not purely self-harm. If you could sign that away - it's basically a slow and horrible suicide method.
I think it's pretty obvious that right implies morally acceptability. You can't claim to have a right to something evil. (The reverse is not true. It is morally acceptable to own a Tesla, but you don't have the right to one.) Alterations can be harmful and any harm that is not a justifiable side effect is by definition immoral. That it's your body does not somehow negate the immorality of self-harm. Indeed, direct self-harm is even worse morally than harm of others because it is in direct opposition to one's own good (arguably, harm of others is also a form of self-harm, specifically harm of one's character and will and habitus, of one's intellect because of the harm of one's reasoning faculties it entails, and harm of the common good). So you cannot say you have the right to self-harm. This is just a strange consequence of the incoherent ideology of absolute autonomy.
Now, if you have, say, a defect in your body that is preventing the proper functioning of your body, then we may correct this defect through intervention. This is restorative, that is, it seeks to restore the function due to the body by virtue of how it ought to function. This is the basis of medicine.
Another false view that can nudge people toward the view that any modification is acceptable is metaphysical materialism, also incoherent. In that case, crude metaphors between artifacts and living things are elevated to the status of the truth and since it doesn't matter what we do to an artifact per se. We can modify a computer any way we wish because there is no fact of the matter about what a computer is or how it should be apart from human intent. It is just a collection of things arranged in a particular way incidentally that puts them in a series of incidental causal relations, but there is no inherent tendency for these things to exist in these relations and no accounting for one in terms of the others except through the lens of human intent. Living things aren't like that.