Lecture 8 – Feb. 4
The Fundamental Principle of Morality according to Kantianism, Proposal #1
The Principle of Universalizability: an act is right if and only if its maxim is
An Act’s Maxim
“The principle of action you give yourself when you are about to do something” (p.147)
1. What you are about to do. (Your intended action)
2. Why you are about to do it
A maxim is universalizable if and only if it is possible to act successfully on the maxim in
a world where everyone acts on this maxim
Possible to act successfully on the maxim = if it is possible to do the intended action and
achieve its intended goal
1. Formulate your maxim
2. Imagine a world in which everyone act on this maxim
3. Ask: Can I act successfully on my maxim in this imagined world?
If yes: the maxim is universalizable and the action is permissible
If no: the maxim is not universalizable and the action is impermissible
• You are going to a Leaf’s game
• Your friend wants to go too, but cannot afford a ticket
• They promise that they will repay you if you lend them the money. But they have
no intention of repaying you
o Is your friend acting in a morally permissible way?
Putting it through the test:
1. Maxim: make a lying promise in order to get what they want
2. Imagine a world in which everyone makes lying promises whenever they think
this will get them what they want 3. Consider: is it possible to successfully act on the maxim in such a world?
Is it possible to successfully act on the maxim in such a world? Kant’s answer: No.
• No one would believe anyone’s promises, and so the practice of promising would
cease to be effective
• Verdict: friend has acted impermissibly
Universalizability and Fairness
When we act on maxims that are not universalizable, we are acting unfairly.
We are acting in a way that can only work because others are not acting in that way.
Evaluating the Principle of Universalizability (POU)
The Lawn Fanatic: “Suppose that someone wants nothing more than to have a picture-
perfect lawn. His basic maxim is to do whatever it takes to preserve the beauty of his
grass… The real thorn in this guy’s side is the mail carrier, who always trots across the
lovely yard on his way to delivering the mail. He has been warned, repeatedly, to use
the sidewalk – to no avail. So the homeowner decides to take matters into his own
hands. The next time the mailman tramples his lawn, the homeowner pulls out a gun
and kills him.” (p. 154)
The Lawn Fanatic
1. The maxim: “take whatever steps are necessary (including killing) in order to
preserve the beauty of his lawn”
2. Imagine a world in which everyone takes whatever steps are necessary to
preserve the beauty of their lawns
3. Consider: Is it possible to successfully act on the maxim in the universalized
Is it possible to successfully on the maxim in the universalized world? yes
Evaluating the POU
Problem 1: there seem to be cases (e.g. the lawn fanatic) in which one’s maxim is