[skohan]

It's a bit different. Yes it's true that, for instance, if a pallet of USD with sequential serial numbers went missing, the FBI would probably knock on your door if you tried to put some of them in the bank. But as far as I know, if those dollars made it into circulation and you obtained them by legal means, it doesn't become illegal for you to spend them.

[DubiousPusher]

It's not that different though. At times there are dollars which have become not fungible. We don't say this makes the whole system not fungible. Because in most transactions, most of the time, people don't distinguish between the units of exchange.

In some highly technical way, is the medium not fungible? Sure. Just as in prison exchange of cigarettes there might be someone who won't take Parliaments and someone else who wants only Marbs. But most of the time, most people, exchanging most coin, consider them interchangable. And in any financial tool that is what matters. Not theory but how people treat it.

[skohan]

Fungibility is not a binary, it's on a continuum. A dollar bill is almost 100% fungible, with some exceptions as you have mentioned. A dollar token (i.e. the number in your bank account) is basically 100% fungible.

Bitcoins are far less fungible. If you can look at all the transactions which have occurred in the past on a given token, and retroactively decide it is unfit for exchange, this is categorically different than saying you can put a dollar bill through the washer and make it unusable.

[Nevermark]

It's not whether people could start judging every satoshi differently, it is whether they do.

Generally, to a percentage very close to 100%, people are not doing that.