[vintermann]

For regular money, "the same coins" isn't usually meaningful. For bitcoin, it is perfectly possible to say yes, this is the same money, and those other coins in the same wallet are not the same.

Since we can track bitcoin perfectly, it's hard to argue people who have the exact stolen item shouldn't be required to return it.

Fungibility is just a social convention. Anything we can tell apart we can decide to treat non-fungibly, and we can tell bitcoin apart.

[uxp8u61q]

I specifically took the example of a (physical) $10 bill. You can definitely tell apart two different $10 bills. They have serial numbers, for example. They're different physical objects.

[vintermann]

Sure. I said we can decide to treat things we can tell apart as non-fungible. I didn't say we had to.

If it's things we can't tell apart (say, liters of oil in the same tank), we are pretty much forced to treat them fungibly. I say pretty much, because there are such things as LIFO and FIFO accounting conventions - sometimes we do our damndest to tell apart things that can't really be told apart.

But if we can tell them apart, it's up to us. We have decided to treat money (incl. physical bills) as fungible in most contexts. With laws.

Even with laws there are limits: If someone wants to pay a debt to me, and offer to settle with a 200 NOK bill, it would be illegal for me to refuse, even if I knew this bill had been stolen from me earlier that night.

But if it was a $10 bill, or a bitcoin, it would be perfectly legal for me to refuse. With crypto tokens in general, there's to my knowledge no government on earth stopping me from declaring that I will take payment in bitcoin minted only on Thursdays.

[oska]

> Fungibility is just a social convention

No, the fungibility of money is law, established by legal precedent. Specifically the case of Crawfurd v The Royal Bank (1749).

> On 30 July 1748, an Edinburgh lawyer named Hew Crawfurd mailed two £20 notes to the merchant William Lang in Glasgow, but the letter was lost. Prior to sending them, Crawfurd had meticulously signed his name on the banknotes and recorded their serial numbers, so he notified the Bank of Scotland and advertised his predicament in several newspapers. One of the notes was never found, but the other note turned up at the Royal Bank of Scotland. Crawfurd requested the Royal Bank to open a multiplepoinding action with respect to the note, but the Bank refused. Thus he brought suit in the Court of Sessions against the Royal Bank.

> Both banks were alarmed by his action, as an adverse finding would subject banknotes to infirmities of title like any other property, which would threaten the idea of paper money as a common circulating currency. Despite their generally poor relations with each other at the time, they agreed to cooperate and jointly defend the case.

https://en.wikipedia.org/wiki/Crawfurd_v_The_Royal_Bank

[vintermann]

> No, the fungibility of money is law, established by legal precedent.

Laws ARE a kind of social convention. And to the degree that the fungibility of "money" is law, law also decides what counts as "money", and there's no reason why they (yes, they, not it - law is actually people) should let your crypto-token of choice count as money for legal fungibility purposes.