“Act in such a way that you treat humanity, whether in your own person or in the person of another, always at the same time as an end and never simply as a means.”
t. Immanuel Kant
No human is an object, they are sentient intelligent beings with a will to do and do not. Either you respect that will to act against your own at times, or you have no grounds to believe your own will deserves to be respected. And yes, that includes retards and women. The question is not the quality of will, but its existence.