> You didn't, others did though, therefore it's a currency
From the first statement you can only conclude that if it’s a currency, then you spend it (by modus tollens). You can’t conclude that if you spend it, then it is a currency.
Why not? It's an abstract concept. Consensus decides whether something fits the definition, or even change the definition so that it fits. And, IMO, if WoW gold is widely accepted to be a currency, then BTC is too. YMMV.
My point refers to those who still bang on the fact that you can't pay BTC directly to buy bread, therefore it's not a currency. Just because it's not used in the economies YOU engage in, doesn't mean it's not a currency. You're just not involved with it.
B: it’s a currency
Here is how the thread went (too lazy for quantifiers and variables).
1. not A => not B
2. So Peso not A => Peso not B
3. You: But Peso A => Peso B
This is a non sequitur. „Not A => Not B“ does not entail „A => B“. That’s what I mean by you can’t conclude it (from the thread). You are however clearly free to make up new things and change the topic. But it looked like you were drawing a conclusion there.
Edit: formatting
You're free to disagree.
Also, from wikipedia:
> A currency is a system of money in common use within a specific environment over time