A maxim is a rule that connects an action to the reasons for the action

Dr. Chuck's Nuts And Bolts of Determining the Moral Status of an Action

The moral status of an action must be determined by evaluating its maxim. A maxim is a rule that connects an action to the reasons for the action, i.e., a motivation/goal/context. So, when you formulate a maxim you must name the action and give the reason. So, a general template for a maxim is:

"I ought to (insert action) ___________ in order to (insert, motivation/goal/context) ________________."

Maxim Examples:

I ought to rob from the rich in order to give to the poor.

I ought not to lie to people in order to take advantage of them.

I ought to cheat on the test in order to get a good grade.

I ought to cause pain to sentient creatures in order to eat meat.

So, to formulate the opposite maxim, you need only insert or remove a "not" in the appropriate place.

Opposite Maxim Examples:

I ought not to rob from the rich in order to give to the poor.

I ought to lie to people in order to take advantage of them.

I ought not to cheat on the test in order to get a good grade.

I ought not to cause pain to sentient creatures in order to eat meat.

For Kant, one determines the moral status of actions by deriving the moral status of the action from the categorical imperative. To be consistent with the categorical imperative, the action's maxim must (1) be shown to be universal and necessary (perfect duty), (2) be shown to be universal and necessarily willed (imperfect duty), or (3) be shown not to be contradicted by a perfect or imperfect duty (morally permissible). To determine whether one has a moral duty to act in a certain way, you formulate the maxim, then check to see if the opposite maxim is self-contradictory. That is, would making the opposite maxim universal and necessary, make it impossible for the maxim to be universal and necessary. I've called this the test of the universal maxim. The idea here is that some actions cannot be universal and necessary because they undermine the relationship between the action and the goal when universalized. For example, the maxim "I ought to kill people in order to attain wealth" cannot be a universal and necessary maxim because in attaining wealth through murder, I would universally and necessarily become the murder target of other people. Thus, I have a perfect duty to follow the maxim "I ought not to kill people in order to attain wealth." To determine if one has an imperfect duty, one tests to see if by willing that the maxim was universal and necessary, people act towards oneself in ways that one would will they act. In other words, would you like people to act that way towards you. So, some maxims could be universalized without undermining the relationship between the action and the goal. However, one's willing of the universality and necessity of the maxim would result in actions that contradict one's will. For example, the maxim "I ought to neglect my friends in order to avoid doing things for them," is not self-contradictory. Nothing about neglecting one's friends in order to avoid doing things for them undermines anyone's ability to neglect ones friends in order to avoid doing things for them. However, were one to will that everyone neglect their friends in order to avoid doing things for them, one would contradict one's will in that one would sometimes like to have one's friends do things. Thus, one has an imperfect duty not to neglect one's friends in order to avoid doing things for them.

Determining Moral Status:

One must perform an action if it is a perfect duty, i.e., you can derive the universality and necessity of the maxim from the categorical imperative.

One ought to try to perform an action if it is an imperfect duty, i.e., you can derive the universality and necessity of willing the maxim from the categorical imperative.

An action is permissible if it is not forbidden by a perfect or imperfect duty, i.e., your are not universally or necessarily forbidden to act in that manner or you are not universality and necessarily forbidden from willing that you act that way.

Example 1:

Do I have a moral duty to rob from the rich to give to the poor?

(1) Formulate the maxim:

I ought to rob from the rich in order to give to the poor.

(2) Formulate the opposite maxim:

I ought not to rob from the rich in order to give to the poor.

(3) Testing for Perfect Duties:

(3a) Test to see if the maxim is universal and necessary by testing to see if it is impossible for the opposite maxim to be universal and necessary. That is, determine if making the opposite maxim universal and necessary would be self-contradictory.

(3b) Is it possible that not stealing from the rich to give to the poor be something that everyone always did?

(3c) Yes, nothing about refraining from stealing to help other people prevents other people from refraining from stealing to help other people.

(4) Result, you haven't shown the impossibility of the opposite maxim's being universal and necessary, so you cannot conclude that the maxim is universal and necessary, i.e., a perfect duty.

(5) Test for Imperfect Duties:

(5a) Test to see if the maxim is such that it ought to be universal and necessary willed by testing to see if it is impossible for the opposite maxim to be universally and necessarily willed. That is, determine if universally and necessarily willing the opposite maxim would be self-contradictory in the sense it would prevent fulfillment of the goal of the action.

(5b) Is it possible that everyone willing that one ought to not steal from the rich to give to the poor would prevent people's goal of not stealing from the rich in order to give to the poor?

(5c) Yes, nothing about willing that one refrain from stealing to help other people prevents other people from willing that they refrain from stealing to help other people.

(6) Result, you haven't shown the impossibility of the willing opposite maxim's being universal and necessary, so you cannot conclude that the maxim is willed universal and necessary, i.e., an imperfect duty.

(7) Conclusion: The opposite maxim passes the test of the universal maxim and the test of the universal will. Hence, you have not shown that the maxim dictates a perfect or an imperfect duty.

Example 2:

Do I have a moral duty not to lie to people in order to take advantage of them?

(1) Formulate the maxim:

I ought not to lie to people in order to take advantage of them.

(2) Formulate the opposite maxim:

I ought to lie to people in order to take advantage of them.

(3) Testing for Perfect Duties:

(3b) Is it possible that lying to people in order to take advantage of them is something that everyone always did?

(3c) No, one of two results would occur: (1) If everyone lied when they stood to gain from the lie, then all statements given under such circumstances would be lies, and hence no one would be fooled by the lie. (2) One is lied to by other people whenever those people stand to gain from the lie. Hence, one is tricked at least as often as one tricks others.

(4) Result, you have shown the impossibility of the opposite maxim's being universal and necessary, so you can conclude that the maxim is universal and necessary.

(5) Conclusion: The opposite maxim fails the test of the universal maxim. Hence, you have shown that the maxim dictates a duty.