Rawls Original Position’s main flaw is it assumes what is right, what we should do, is what an agent wills for themselves if they could be any hypothetical being with any given traits within that society. Like Kant’s Categorical Imperative, it assumes that the will of the rational agent is a valid tool of determining normativity without conclusively arguing it. It is true that if I consider wronging someone for my own advantage and then consider the universal law, “one can harm others if it gives personal advantage to one’s self” then the situation could arise where I become harmed for someone else’s gain. An agent who is both self-interested and invested in the idea of ethical universality will then be tempted away from exploitative acts for they would not like to be exploited.
However, that moral laws can be known to be constructed from the wills of rational agents is completely a figment of the human intellect. Also, although Kant criticizes “empirical morality” it is in a sense empirical in that my feelings towards being treated one way or another is visceral rather than purely rational. It creates a feeling inside of me, of satisfaction or dissatisfaction and I will that I be treated in a way that creates a feeling I wish rather than one I not. I wish that my autonomy is respected as oppose to not, and although it is conclusive that the Categorical Imperative would have me then respect the autonomy of others what is not conclusive is that my own wishes have anything at all to do with what ought to be. Kant sets out to salvage ethics from the whims of Utilitarians and Divine Command Theorists but is left with nothing but human whims outside of rejecting actions for being impossible if they were universalized.
Since it is the case that the fundamental nature of imperfect duties, ones that are not necessary but preferable are ones that involve the agents will and not their reason, then animals which can will should be included despite the fact they cannot reason the C.I. themselves. For if being a being that can reason the CI is a requirement, then it not only is something that the mentally challenged would fail, but it would require the CI to be based on purely rational grounds, rather than subjective and empirical grounds. Kant acknowledges it is a product of the human imagination, what should instead perhaps be called will, that desires happiness. Since all of our selfish desires are in effect to attain happiness, as Aristotle and the Utilitarians acknowledge, it seems that the large majority of our individual wishes for us, that which we would universalize through the CI, would be based on this will for happiness rather than on pure reason.
The reasoning part of the mind cannot desire anything, it can only either follow true or false premises to valid or invalid conclusions, or it can infer the probability of something occurring through witnessing like events with comparable variables happening before. It is the reasoning part of the mind which believes the rocket will or will not reach its target when it is launched. It is the sensual and desiring part of my mind that desires that it will kill or spare certain names, that lives will be saved or not be saved, that the Earth should continue spinning on its axis or crash into the sun. Kant could very well be right in saying that, “if you should be treated with respect, then you should treat others with respect.” What he cannot ground in reason is the divide between the feeling I have of wanting to be treated with respect and claiming that I ought to be.