Birmingham and others also point to another theory: the entitlement of an executive. Romney, they say, simply does not like having his authority challenged by people he considers less than his equal. “He has a very corporatist approach to governing, and, in corporations, they’re not democracies,” Birmingham says. “Leaders give orders and they’re expected to be followed. He’s very accustomed to having his way obeyed.”

I heard a slight variation on this theory from someone who was a high-level Romney appointee in Massachusetts. This person observed that Romney is not a typical “command and control” executive, alone in his corner office. Rather, he is most comfortable surrounded by other smart people of similar station to his own, which this person attributed to his background in management consulting. “One of the nice things about being a consultant is that you learn to be a strong leader in some situations, but you have many other peers of equal caliber,” the former appointee says. “He’s more comfortable in that peer-leadership role.” This might explain why people I spoke with who worked alongside Romney at high levels said they rarely witnessed Romney as anything but collegial and easygoing. Perhaps among his own element, he generally is able to hold things in check.

There is one final theory that might explain Romney’s occasional outbursts: He may simply be a genuinely quirky person.