The necessity of using reason as the determinant for establishing law as implies that reason carries an inherent value in itself and those who possess it. Human beings inherently possess value as they are rational beings and should always be treated with dignity and respect. The humanity present only in human beings gives us all a great deal of inherent value that is not present in any other being. This leads us to the next point where we review the use of rational beings as means, means to an end, and as an end in themselves. When discussing these points, it’s important to remember that Kant acknowledges that self-interested motives are present in actions and permits this; insofar as we act morally and insofar as our actions reflect the moral worth of the duty as the priority. This is comparable to the limitations of using human beings as means and means to an end. The most important factor to keep in mind when determining whether it is morally permissible to use other human beings as means/ means to an end, is whether their dignity is still respected and preserved. For example, we may use another person’s services in an agreed upon exchange such as a taxi driver being paid for the service of transportation. This is consistent with Kant’s message to “Act that you use humanity, whether in your own person or in the person of any other, always the same time as an end, never merely as a means”(4:429) In the case of the taxi driver, there is an element of an end being pursued in the exchange of money for transportation to a destination. Another example where someone is used both as a means and an end in themselves is tutors and students; where, the tutors provide a service of teaching to their students in exchange for a fee. Nevertheless, in each of these instances it is still possible for one or both of the individuals involved to take unfair advantage over the other if they fail to honour their end of the agreement.
While it is only natural for all human beings to feel motivated by their inclinations and desires, it is important to realize how this subjectivity ignores the conditions of the supreme principle of morality. These motives towards action should only be conducted if they have the support of duty in the preservation of the respect for an individual’s humanity. While it is in no way immoral or unacceptable to have respect for someone’s achievements, it is not the type of respect Kant is referring to. We are meant to respect human beings because they are sentient beings with humanity; and, this humanity cannot be taken away regardless of any misdeeds or vicious acts they may commit. Here we begin to approach controversial territory when we consider how many people would feel regarding Kant’s point of view. We see that human being who commit atrocious deeds are punished by the legal systems and must serve a sentence in prison or pay a fine in order to make reparations for the damages they have caused. Consequently, according to Kant’s proposal that humanity cannot be taken away, these reparations can be seen as limitations on the free good will of individuals. Not only do the perceptions of the individuals being punished change, but also the views of their peers and complete strangers. Now, it is difficult to argue that those who commit misdeeds and crimes should not be punished; however, does the current socially accepted form of punishment limit or hinder the humanity of these people? If it does, then the current system of punishment should be deemed immoral and restructured so that it no longer does.
The last hypothetical situation of where the Formula of Humanity may fall short of being declared the supreme principle of morality is cases where human beings are incapable of using reason. In such cases, the lack of reason may imply the lack of an ability to grasp key elements of the Formula of Humanity, such as the freedom of the good will and arguably the required respect of humanity. If a human being is incapable of reason how can they be held to the same standard as people who are capable? As previously stated, a requirement of the Formula of Humanity is the respect of human being for the capacity for reason and thus an inherent respect for their humanity, should this rational element be absent is it possible to conclusively say that they are deserving of the same respect rational beings are? This would mean that the Formula of Humanity is no longer universal and disqualify it as a suitable candidate for the supreme principle of morality.