Basically, Kant wanted to differentiate between humans using their pure reason (thus confirming our specialness, as the only creatures who can do that) and the rest of the beasts in the lower, animal world, where emotions and feelings reign supreme and events unfold due to these baser passions. That’s why things like happiness and fear have to be taken out of the equation when we’re looking at motivations—I mean, cows and porcupines can feel happiness or fear, and we’ve gotta be better than some dumb porcupine munching on a twig.
