That’s a very good point. However, I would still call it a failure of rationality if it went like this:
Alice: Chocolate is best.
Bob: No, vanilla is delicious.
Me: I don’t really like either of those, so let’s get pistachio.
A&B together: There’s no such thing as ice-cream flavors other than chocolate and vanilla. Now hurry up and cast the tie-breaking vote!
That’s a very good point. However, I would still call it a failure of rationality if it went like this:
Alice: Chocolate is best.
Bob: No, vanilla is delicious.
Me: I don’t really like either of those, so let’s get pistachio.
A&B together: There’s no such thing as ice-cream flavors other than chocolate and vanilla. Now hurry up and cast the tie-breaking vote!