Kant, the categorical imperative


Deontological ethics is an ethics of duty. In contrast to consequentialist theories, deontological views do not evaluate actions primarily on the basis of their estimated consequences. Rather, they catalogue certain classes of actions as right or wrong in themselves and propose commands or imperatives to follow and avoid various kinds of actions. These commands become universal imperatives. The code of ethics of the ten commandments is an example of a deontological theory. Thou shalt not steal! Thou shalt not kill! Honor thy father and mother! In the philosophical tradition, the best known of the deontological theories was proposed by the 18th century German philosopher, Immanuel Kant. Various theoreticians who adopt key ideas of his have then gone on to work out further deontological theories that are often considered “Kantian” or “neo-Kantian.” These theoreticians don’t accept all of Kant’s ideas but do accept some basic characteristics of his approach. For example, some of these Kantian, also give much more importance to weighting consequences than Kant does in developing their moral views. A discussion of at least one neo-Kantian approach will be taken up later.

Free will

In his ethics Kant emphasizes human free will. In contrast to other objects in the natural world, which are simply subject to natural laws, humans give themselves their own laws. Humans are self-legislating. To clarify the contrast, if I drop a pen to the floor, it doesn’t decide to follow or not follow the law of gravity. It simply follows the law of gravity, as it must, and falls to the floor. Humans are different. While as physical objects humans too are subject to law of gravity and other physical laws of nature, because of our rationality we additionally have a domain of activity that is not subject merely to physical laws of nature. In this domain we provide ourselves with our own principles. We do this, mind you, whether we want to or not. It’s not an option: Each of us simply must provide ourselves with our own subjective principles, which Kant calls maxims. We use these to guide our behavior in the world.

Rational will

Kant’s ethics, as is well-known, also focuses on the importance of a good will. Yet it is important to see that he understands our will as good, not if have mere good intentions, but only if we choose rational subjective principles. A good will, for Kant, is a rational will. (For more on the distinction between good intentions and a good will see my blog comment.)

Kant’s categorical imperative serves to allow us to determine the specific principles that each of us should accept as our subjective principles (that is, our maxims). In short, the categorical allows us to understand what principles are rational, thus what principles we should adopt in order to have a good will.

Though Kant has various formulations of his categorical imperative, which he calls “formulas,” I will for now only highlight two of them: the universal law formula and the humanity formula. Again, both of these formulas, as well as the others, are to help us understand what principles are rational and thus what principles we should adopt in order to form a rational will.

A Kantian view of practical rationality

Kant’s view of what is rational differs fundamentally from the view of Hobbes or rational choice theorists on what is rational. Hobbes, like later rational choice theorists, views it as rational to act in our own narrow self-interest, and as traditionally formulated, regardless of what that understood self-interest is. Kant disagrees. In Kant’s view, if we are rational, then we cannot act merely to achieve some set of goals that we happen to have. Rather, if we are rational, we will act on the basis of a principle that we can rationally affirm that all others can also make their principle of action.

A conflicting view of rationality and the tragedy of the commons

Let’s reflect on this issue of rationality in reference to the traditional tragedy of the commons to try to clarify this. Imagine 5 fishermen who all have the possibility to fish the same pond sustainably only if they catch 10 fish or fewer per day. (We can imagine that the amount that others take from the pond is very limited and stable. Given the fishing of the five, which is daily, and others, the lake produces enough fish for each fisherman to take ten fish per day.) What should the individual fisherman do? According to the “economic” logic identified with Hobbes and rational choice theory, assuming he needs or can otherwise benefit from more than 10 fish, it is rational for each fisherman to take more than that as long as he can do so without any negative repercussions from the others involved. In fact, given the assumption of the Hobbsean worldview, unless a mechanism for punishment is in place, it would be individually irrational for the fisherman to only take ten fish per day if there is an individual benefit from taking more fish than that, since he must assume that the other four fishermen will all also see it as in their rational self-interest to take more than the sustainable number of fish, given that they can make money from selling the extra fish, or in some other way benefit from that extra fish. And if the one individual fisherman doesn’t deplete the lake, the others will. So, for the Hobbsean, the rational thing for the individual to do is to catch as many fish as possible for himself before the lake is depleted of fish by the others. In the language of rational choice theory this is individually rational. It is however not socially rational. The socially rational action would be to fish sustainably — that is, to take no more fish than can be replenished in the lake. Again, though, given the assumption of rational choice theory that others will not be motivated by good will, but by a narrower self-interest, it is not individually rational for any individual fisherman to fish sustainably if he stands to benefit from doing otherwise. The tragedy of the commons, that is, for public areas like the lake under discussion, occurs because unless there is some means of enforcing limits on fishing, the five fishermen — to remain with our example — will deplete the lake; and over the long haul none of them will then be able to fish the lake. The tragedy in this case is that a lake open for use to these five individuals, which would have been a stable supplier of some food, will become a fishless body of water. Each individual, by pursuing a course of action that is supposed to be individually rational ends up with a long-term situation in which all five fishermen are worse off. In a rational choice scenario, this tragedy could be averted either by a legislative action and adequate policing or privitization of the commons (the lake) with some means of enforcement of property rights.

The universal law formula

Kant disagrees with the view of rationality described above completely. Kant does not distinguish between something individually rational, but socially irrational, or socially rational but individually irrational. His universal law formula of the categorical imperative is to help us decide what is rational, period.  That formula states: “Act only on that principle that you can will at the same time to be universal law.” Applying this to the scenario described above, only one thing is rational: Each fisherman should act on the principle that he could will that all others make their guiding principle. He should fish sustainably. In Kant’s view, anything else would lead to a contradiction. Unsustainable fishing undermines the long-term conditions under which fishing is possible, so it would be a contradictory act.

Kant’s universal law formula highlights that we are self-legislating. We are to give ourselves a universal law. His writing on this also highlights the fundamental equality of all people. There is not one law that applies to me and an unequal one that applies to others. One law fits all, at least in theory. (As we will see, this issue in fact is complicated by Kant’s own acceptance of the gender and various other biases of the 18th century. In reality, one size fits all white European men. But for now let’s try to ignore this complication, if we may.)

The humanity formula

Kant seems to have recognized that framing the issues differently with these different formulas would be helpful for clarifying concrete principles. The humanity formula (like the other formulas) is meant to compliment the universal law formula of the categorical imperative. Applying the humanity formula, we should reach the same results as with the universal law formula or any of the other formulas. This framing, though, might help enlighten our thinking in some contexts. Kant’s humanity formula states: “Act only on that principle by which you treat humanity, whether in yourself or in another person never merely as a means but always also as an end.” In Kant’s view, because of the fact that we have free will and are self-legislating (which are both conditions of our being rational), we understand ourselves as being worthy of respect. That same respect that we find that others owe us, we in fact also owe other self-legislating rational individuals. We must thus act on a principle that acknowledges this universal respect or dignity. Perhaps the following is a legitimate short-shift for the humanity formula of the categorical imperative: We must treat ourselves and others with dignity and respect. We should never treat ourselves or others as mere means.

What does it mean to treat someone as a means? Simply put: we should not merely use people. All people deserve to be treated with dignity. There is an operative word in the formulation about means, however. Kant does not say that we may never treat people as a means. He says we may never treat people merely as a means. The lawyerly parsing is important. In principle, Kant does not have a problem with us having use relationships with people, or putting ourselves in use relationships with others. If we go to a bank teller to ask for change for $100, we are involved in a use-relationship with that teller. This is not unacceptable. Indeed, it is inevitable that we engage in use-relationships with people. What here would be unacceptable is if we were to treat the bank teller with disrespect. So too, Kant does not have a moral issue with employer-employee relationships. An employer hires an employee, paying them for their labor power. This is a use relationship. Kant sees no wrong here per se. The wrong would be if the employer reduced the employee to her labor power, if the employer was in an exploitative relationship with the employee. As long as the employer pays a fair wage, and creates a safe, fulfilling workplace (0r fulfills whatever we rationally deem as necessary for a respectful workplace), all is good in the view of Kant.

Kant thinks that the various formulas of the categorical imperative will help us to decide what principles we can legitimately accept as we self-legislate. In the case of fishing where there is a threat of the tragedy of the commons, we have seen that the universal law formula should lead us to accept that we should fish sustainably. In the case of dealing with bank tellers or employees, we would be able to formulate some other concrete principles. The different formulations can facilitate clearer insights in one case or the other. Kant thinks they lead us unerringly to principles that determine our will as good.




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  • Hugo Hiraoka
    October 23, 2018 at 4:22 am 

    This is a very interesting article that explains Kantian ethics very well. While I was reading about the 5 fishermen example and Kant’s Categorical Imperative Universal Law Formula to determine what is rational (and thus moral), I imagined the daily situations that I encounter and that makes me wonder if I live in the right place. Just as one of the many examples that I can think of, consider my local Walmart store.

    Every time when I go shopping there, I’m always shocked at the number of shopping carts left anywhere: on sidewalks, on pathways, on crossways, on parking spots, behind cars, in front of cars, etc. As we all know, there are designated areas to return the shopping carts. But customers just don’t return the carts to these reserved areas. Why? Is it because they think that this is part of the service that Walmart (and this same scenario applies to most other stores where I live) should provide? Is it because they only think about their own convenience? Is it because they think it is all right because others do it (social empowerment)? Do they ever think about the inconvenience they can cause to others?

    Not returning the carts to the right area cause many issues:
    – Cars can be damaged by rogue carts,
    – Some customers will have to move carts away to leave the parking lot,
    – Many arriving customers will park farther away to avoid the risk of damage by carts,
    – The parking lot may look like a war zone,
    – Walmart employees will have to invest more time to collect shopping carts which may lead to the store not having shopping carts for arriving customers,
    – Walmart’s cost will increase, etc.

    According to Kant, we have free will and are self-legislating. But Deontological Kantian ethics fails miserably in this scenario (but maybe not necessarily Utilitarianism?). First, the set of rules are not universal. They only apply to some people. I always return my shopping cart to the designated area, it applies to me. But why others can’t do the same? They can’t legislate themselves? And while Kant states in his Humanity law that one should not treat people’s as a mere means to an end, he also talks about treating others with respect and to “act accordingly to how you would like to be treated in return”. It seems that the Humanity Law doesn’t seem to apply to these people either.

    I would believe that these “happy” customers that leave the shopping carts anywhere, would not appreciate having to walk a long distance because they were not able to park their cars in close parking spots that are occupied by left-behind carts, right? So where is the self-governing principle?

    Now consider the supermarket ALDI. How many shopping carts have you seen abandoned on the parking lot? If you have been there, you probably have rarely seen one. That is because to get a shopping cart at ALDI, you must first place a Quarter on the locking mechanism. You only get your coin back when the cart is returned to the designated area. So, rational choice is right (which Kant says is wrong)?

    • Darrell Arnold
      October 23, 2018 at 7:42 pm 

      I much enjoyed your inquiry, Hugo. I think that as a matter of public and organizational policy counting on people to fulfill their moral duties is likely to lead to disappointment. Kant would say that the fact that we are self-legislating does not mean that everyone will legislate themselves wisely — morally and rationally. Some people will act on principles that are not universalizable. Indeed, in at least contexts like the one you are describing it seems that perhaps most people (in the U.S.) will act on principles that are not universalizable. Kant would still say that they should act on other principles — even fully recognizing that since we are free not everyone will act on such principles.

      As a matter of practical policy, we are likely to often be best served not by expecting people to do what is rational but by incentivizing people to do what is rational even if they don’t want to do that without the incentive. You example of Aldi shopping carts is excellent. Recognizing that, regardless of what people should do, many people will not take back shopping carts without an incentive, Aldi (like supermarket chains throughout Germany) thus encourages the good behavior — taking back the shopping carts. This indeed has the positive social benefits you note. It prevents carts from being scratched or dented by carts in the lot. It means that many people who park will be able to park closer to the shop since those parking spots will not be blocked by the carts, etc. In addition, it even saves Aldi money, since it doesn’t have to have employees collect the carts. It can pass on the savings in higher wages to the employees who are there or to savings to the customers.

      Kant’s view of the categorical imperative might help us in the formulation of some laws. But trusting that people will act out of a sense of moral duty is likely to lead to frustration. We will often be better served by recognizing that in many circumstances people will in fact be motivated by narrow self-interest. We can then, as you note, use mechanisms of rational choice theory to incentivize behavior that leads to the favorable social outcomes desired. Here too, the will of those involved is at best of secondary importance. We want to incentivize good behavior even if it is done begrudgingly or individuals would not have opted for it had their not been the right (negative or positive) incentive.

      In the case I mention in the post about fisherman, I would also underline that relying on people to act on moral duty would likely lead to disappointing results. Yet that doesn’t mean there isn’t a moral duty. That just means that people are sometimes quiute willing to ignore the duty. The problem I outline is known as the tragedy of the commons. Two main responses have been proposed to address it. One offers a carrot, the other threatens with a stick. The carrot solution sometimes proposed is that of private ownership. In some cases privatizing the property, a lake, could mean that individuals would take care of it in a way that they would not take care of a lake. So in some cases, that could address the problem. However, what if privatizing this lake meant that the owner only fished for himself and the others who fished it lost out on making a living from fish (or from the subsistence living generally). This could be a negative social impact even if it did lead to the ecological use of the lake. The stick solution is to penalize those who overfish, for example, fining them something substantive enough that it leads to the desired behavior. This can work in some circumstances. Yet it can also be expensive. In general, the lack of cooperative behavior that would accord with Kant’s categorical imperative often does lead to greater social costs. Because people often are not moral, costs rise for us all as we have to increase policing or regulative efforts, which, as we know are not free.

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