A fun unsound argument for dualism

Here’s a fun argument for dualism.

1. What is a part of the body is a matter of social convention.

2. Persons are explanatorily prior to social conventions.

3. So, probably, persons are not bodies.

I think (2) is undeniable. And (1) is a not uncommon view among people thinking about prostheses, implants, transplants and the like.

That said, I think (1) is just false.

Self-ownership and organ sale

1. Things owned can be permissibly traded, barring special circumstances.
2. Trade in persons is never permissible.
3. Thus, no one owns a person. (By 1-3)
4. Thus, no person owns herself. (By 4)

(By the same argument, God doesn't own us, either. We belong to God, of course, but not by way of ownership.)

Let's continue thinking about self-ownership:

5. If x is not simple and I own every proper part of x, I own x.
6. I don't own myself. (By 4 and as I am a person)
7. I am not simple.
8. So, there is a proper part of me that I don't own. (By 5-7)
9. All my proper parts are on par with respect to my ownership of them.
10. So, I don't own any of my proper parts. (By 8-9)

While I think the conclusion of this argument is true, I am less convinced by it than by the earlier argument. I think 9 is not completely convincing given dualism: spiritual parts perhaps aren't on par with physical. I am far from sure about 7. And I could see ways of questioning 5. Still, it's an argument worth thinking about.

Suppose the argument is correct. Then we have a further interesting argument:

11. My organs are proper parts of me.
12. It's wrong or impossible for me to sell what I don't own.
13. So it's wrong or impossible for me to sell my organs. (By 10-12)

While I am sympathetic to the conclusion, I worry that this argument may equivocate on "organs". Aristotle says that a severed finger is a finger in name alone. Perhaps 11 is true of a kidney as it is found in me, but once the kidney is removed from me, the kidney perishes and a new kidney-like object—a kidney only in name—comes into existence. The kidney-like object is not a part of me, and it is this kidney-like object that is being sold, not the kidney that was a part of me. Still, this isn't clear: maybe the kidney that was a part of me is what is sold, since it is for the loss of it that I am being compensated if "I sell my kidney."

More worryingly, if the above argument were sound, it seems it would be sound with "organs" replaced by "hair". But it doesn't seem wrong or impossible for me to sell my hair. Perhaps, though, we should modify 9 to read:

9*. If I own any one of my living proper parts, I own all my living proper parts and a fortiori all my non-living proper parts.

Then the conclusion is weaker than 10:

10*. I don't own any of my living parts.

This could allow me to sell my hair and some gold atoms in my body, but not my kidney.