Sometimes, they are even divided on psychological questions that psychologists have already answered: Philosophers are split evenly on the question of whether it's possible to make a moral judgment without being motivated to abide by that judgment, even though we already know that this is possible for some people with damage to their brain's reward system, for example many Parkinson's patients, and patients with damage to the ventromedial frontal cortex...

Huh?

Examples like that are the bread and butter of discussions about motivational internalism: precisely the argument that tends to get made is that because it's not motivating it's not a real moral judgement. You may think that's stupid in other ways, but it's not that philosophers are ignorant of what psychology tells us, some of them just disagree about how to interpret it.