[shanusmagnus]

The usual definition of fungible is that one coin (more precisely, one spend output) is as good as another (e.g., the same amount coming from a different UTXO) and they are not distinguishable from each other due to their provenance.

Put more simply, if the coins can be 'tainted' because they were transferred to you from a ransomware hoard then they're not fungible because a merchant could say: "I'm not taking those coins, I don't want to be associated with ransomware. You have to pay me with other coins."

Neither BTC nor BCH has this kind of fungibility, though Monero does.

[dane-pgp]

I could see (some) merchants applying a blacklist to wallets that are known to be "evil" (as decided by some third party, somehow), but it's hard to imagine a non-negligible proportion of the bitcoin marketplace ever blacklisting all coins which have at any time in history been held by a ransomeware writer. The possibility of denying business to innocent customers is too great, and the benefits too small.

If some bizarre counter-productive legislation does come in requiring such a system for bitcoin, then yes, Monero might suddenly become more fungible in practice.

[hndamien]

There is no "more fungible". It is either fungible or it isn't. Provenance can either be determined, or it can't. Sure there may be a degree of difficulty to determine provenance for some things, but if you cannot determine provenance at all, there is no degree.

[dane-pgp]

"Fungible: being something (such as money or a commodity) of such a nature that one part or quantity may be replaced by another equal part or quantity in paying a debt or settling an account"

That definition doesn't mention provenance, even if I concede that something can't be "more (easily) determined" or "less (easily) determined".

My point is that if 99% of debts can, in practice, be paid (or transactions made) without either party paying any attention to the provenance of the coins, then the coins are fungible.

If there were reports of a significant number of a people being unable to transact because their bitcoins were blacklisted, then I would believe that bitcoin is significantly less fungible.

Whether that lack of fungibility is more significant than Monero's differing level of merchant adoption (for which I also don't have statistics) is then another question that a user has to weigh up.

[hndamien]

It would be very unfortunate to be in that 1%, particularly if the implications were dire economically or for liberty. 1% is an enormous percentage. I personally wouldn’t even settle for 0.1%.