Final answer:
The categorical imperative, as proposed by Kant, is a universal moral law that dictates we should act only in ways that could be universally applied. For instance, a lie to escape trouble would fail this test because universal lying would negate trust and the utility of lying.
Step-by-step explanation:
The categorical imperative is a central concept in the moral philosophy of Immanuel Kant, distinguishing it from hypothetical imperatives, which are conditional and aimed at a specific goal.
Unlike these, the categorical imperative serves as a universal moral law that Kant believed should be followed unconditionally, guided by reason, regardless of one's desires.
Kant's most famous formulation of the categorical imperative is: "Act only according to that maxim whereby you can, at the same time, will that it should become a universal law."
This means that any action we take should be one that we would be willing to see adopted universally.
For example, consider the maxim "It is permissible to tell a lie to get out of trouble."
If this were universalized and everyone lied to get out of trouble, trust would erode and the purpose of lying (to be believed) would be undermined, rendering lies ineffective.
This contradiction and general unworkability in a universal scope reveals that lying, according to Kant, fails the test of the categorical imperative and is therefore morally impermissible.
However, Kant also warned that the categorical imperative should not be misapplied by incorporating peculiar definitions and qualifiers in the maxim designed to justify otherwise immoral actions.
The idea is to engage with the spirit of the law, not attempt to find loopholes in its letter.