The question of moral action is not an issue for two classes of beings, according to Kant. The animal consciousness, the purely sensuous being, is entirely subject to causal determination. It is part of the causal chains of the empirical world, but not an originator of causes the way humans are. Hence, rightness or wrongness, as concepts that apply to situations one has control over, do not apply. We do not morally fault the lion for killing the gazelle, or even for killing its own young. The actions of a purely rational being, by contrast, are in perfect accord with moral principles, Kant says. There is nothing in such a being’s nature to make it falter. Its will always conforms with the dictates of reason. Humans are between the two worlds. We are both sensible and intellectual, as was pointed out in the discussion of the firstCritique. We are neither wholly determined to act by natural impulse, nor are we free of non-rational impulse. Hence we need rules of conduct. We need, and reason is compelled to provide, a principle that declares how we ought to act when it is in our power to choose
Since we find ourselves in the situation of possessing reason, being able to act according to our own conception of rules, there is a special burden on us. Other creatures are acted upon by the world. But having the ability to choose the principle to guide our actions makes us actors. We must exercise our will and our reason to act. Will is the capacity to act according to the principles provided by reason. Reason assumes freedom and conceives of principles of action in order to function.
Two problems face us however. First, we are not wholly rational beings, so we are liable to succumb to our non-rational impulses. Second, even when we exercise our reason fully, we often cannot know which action is the best. The fact that we can choose between alternate courses of actions (we are not determined to act by instinct or reason) introduces the possibility that there can be better or worse ways of achieving our ends and better or worse ends, depending upon the criteria we adopt. The presence of two different kinds of object in the world adds another dimension, a moral dimension, to our deliberations. Roughly speaking, we can divide the world into beings with reason and will like ourselves and things that lack those faculties. We can think of these classes of things as ends-in-themselves and mere means-to-ends, respectively. Ends-in-themselves are autonomous beings with their own agendas; failing to recognize their capacity to determine their own actions would be to thwart their freedom and undermine reason itself. When we reflect on alternative courses of action, means-to-ends, things like buildings, rocks, and trees, deserve no special status in our deliberations about what goals we should have and what means we use to achieve them. The class of ends-in-themselves, reasoning agents like ourselves, however, do have a special status in our considerations about what goals we should have and the means we employ to accomplish them. Moral actions, for Kant, are actions where reason leads, rather than follows, and actions where we must take other beings that act according to their own conception of the law into account.