Kant, in Groundwork of the Metaphysics of Morals, presents an argument for the existence of a Moral Law, referred to as a Categorical Imperative (CI). He claims that this can have 3 formulations : the ‘Universal Law’ formulation, the ‘Kingdom of Ends’, and the ‘Formula of Humanity’ (FH) (Guyer, 1995). I examine the last, and argue that Kant was correct to say that we should always treat rational beings as ends in themselves. I outline Kant’s specific reasoning for FH and defend it from theoretical criticisms and practical implications, verifying the correctness of Kant’s practical imperative.
The argument for FH
Kant’s aim in Groundwork is to ‘ground morality on its genuine principles (G 412) ; he must a priori prove that reason alone leads to moral principles. He argues the opposite way, however, beginning with ‘Common Rational Moral Cognition’ (G 393). He identifies the source of goodness in common moral actions as a ‘Good Will’ done from ‘Duty’, denying any role for inclination ‘ instead, value lies in the quality of the ‘Maxim’ instructing the action. He identifies that there exists a system of objective maxims which constitute the ‘Moral Law’, which is universal. The CI, a formulation of which is FH, explains which maxims constitute the Moral Law.
Kant begins with UL, derived analytically from the previous section: since there is a universal law, it must consist of universal maxims ‘ so ‘act only on universalisable maxims’. The practical imperative, then follows:
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.
(G 429)
Kant ‘steps into ‘a metaphysics of morals’ (G 427) and derives the argument for FH from a synthetic application of UL to a rational being (Guyer, 1995). He begins by defining rational beings as beings who make decisions with reference to ends. Ends are objects for which you act ‘ goals of an action – e.g. happiness; means are objects utilised to achieve ends. Usually ends are contingent upon inclination. However, there exists an end in itself: it is grounded a priori in reason, and has absolute worth (Denis, 2007). It does not depend on inclination. It must exist, because it serves as an end for everyone to follow, and is thus an ‘objective principle of the will’, which is the CI (G 429). If it didn’t exist, nobody would have a common guiding principle, and thus no CI could exist; since CI is previously proven, ends in themselves exist. This concept is the link between CI and moral law: by definition, rational creatures need ends, so in order to follow the universal duty there must be a universal end.
This is then applied to humanity as an argument of elimination. Considering what exists ‘ objects and inclinations, things and persons (G 429) ‘ only persons could be considered ends to themselves, since others can only have relative worth. Since there are many persons with the same end (i.e. their own rationality), this transfers from a subjective an objective end: one for everyone, all the time. To use another’s rationality without giving it autonomy is to defy reason itself, from which morality is derived.
To summarise, the argument takes three parts: 1. Rational beings decide according to ends, and so there must be an end by which others are grounded. 2. This end is reason. 3. It must apply to humanity’s rationality, universally. Step 3 is ostensibly an argument by elimination.
Derivation of reason
I shall now debunk various criticisms of this argument, starting with a problem of reason. Guyer (1996) finds a problem with the first premise: ‘rational nature exists as an end in itself’. He points out that rationality as this fundamental principle of morality is indemonstrable: there cannot be a derivable fundamental principle for morality, since if it could be derived, then it would not be fundamental. This implies Kant’s claim that reason underpins moral value, since nothing can be deductively proved to underpin anything. This need not pose a problem, however: it can be acceptable for this to be an inductive argument ‘ indeed, in the opinion of scholars such as Korsgaard, this is what Kant is doing – taking an inductive step into reality by applying the UL formulation to real life (Korsgaard, 1986). We can say that this theory simply fits reality the best, and it is probable that it is correct. Secondly, if rationality and human nature are empirically the same, then rationality can exist a priori as a fact of existence. Thirdly, it is unclear where the objection leads: perhaps ‘if nothing can be proven deductively to underpin morality, does morality exist at all?’ This implies unnecessary scepticism.
Humans as Ends in Themselves
Concerns have been expressed about Kant’s argument that only persons can be considered ends in themselves. His argument appears to be a weak form of elimination: Kant does not defend his statement that ‘all objects of inclinations have conditional worth’ (G 428 in Kerstein, 2001). This implies that things are valuable only because we desire them. Yet this seems backwards: surely it is more appropriate to claim that we desire things at least in part because of some inherent value they have in themselves. Kerstein (ibid) also raises the possibility of the ‘state of everyone being happy’ being a viable candidate for the ultimate end, that Kant has unfairly dismissed.
Korsgaard has proposed a reinterpretation of Kant’s argument as a regress upon conditions. The argument runs as follows: There exists an unconditional source of goodness separate to ends. This source is rational choice ‘ which is what confers value onto a good end (Kerstein, 2001). This is not an argument by elimination; instead it works the other way, saying that in the act of setting ends, you commit yourself to the idea that your method of end-setting is unconditionally valuable (Kerstein, 2006). This argument is not unchallenged: rational choices conferring value require that value does not exist outside the system of morality ‘ a constructivist view. Wood (1999) challenges this concept with a realist view: value exists in humans themselves, and rational choice is the expression of an understanding of this value (Arroyo, 2011). For Wood, rational nature simply has ultimate value; it is separate from the process of end-setting. Both of these arguments are solutions to the issue at hand. Realists solve the problem by saying that, since rational nature is a priori ultimately valuable, and humans express this, we can confirm that humans are the sole ends; Constructivists say that rationality lies within human expression. Both share the key rebuttal of the objection, the regress on conditions: when you set an end, your rational nature must have unconditional value (the source of which, be it from within or existent, does not matter), since you can’t make decisions without an unconditionally valuable basis.
Practical implications of FH
We have seen two theoretical objections: that rationality is indemonstrable, and that humans can’t be proved to be the ends in themselves. Now I shall turn to two upshots of adopting FH. Firstly, the FH disavows killing; thus it is vulnerable to a ‘suicide to save the world’ scenario. Hill (1980) argues that, even though you cannot assign value or compare humanity, you can still have a justified reason to end human life. Assuming that the formulations are equivalent, the universal maxim of doing whatever one can to continue the existence of humanity would be applicable. Admittedly, Hill does leave the ‘look at other formulations’ solution open to the problems of equivalence of the formulations ‘ this has been discussed elsewhere .
Finally, Kant, in holding rational nature to be the binding virtue, eliminates the prospect of children, the mentally disabled, or animals to be moral actors. This is troubling, because there is no clear delineation of what constitutes rationality; and we also intuitively hold children to be capable of some moral virtue. Kant might reply that rationality is not absolute ‘ it is still uncertain what it entails (note that this does not invalidate arguments for rationality’s existence, simply its nature). Since objections regarding non-rational beings concern the nature of rationality, we can say that this is an objection relating to whom FH should apply, and not a disproof of its existence among whatever rational beings are.
Conclusion
I have presented a summary of Kant’s argument, and defended it against two theoretical and two practical objections, which survey a large section of criticism. I do not believe there are serious issues with Kant’s Formula of Humanity ‘ his reasoning was correct, despite some ongoing debates over interpretation.