Ah...this one comes up every now and then. Generally, if the FO is flying, and initiates a go around, there is only a very small window in which it's even possible to abort the abort. If the conditions are such that a go around is likely, then perhaps the FO shouldn't be flying in the first place.
If the Captain is flying and is called by the FO as being "outside limits", or "minima, no contact", then it's a mandatory go around. If the Captain says "go around", then it's an order, not a suggestion.
It's always the Captain's aircraft, and he is entitled to take it back from the FO at any time he chooses.
