Answer: Casual Sex
Forced Sex
Explanation: Kantian philosophy believes in treating humans as humans for the sole sake of being humans. In Kant's view, casual sex or any form of sexual activity outside marriage, whether consensual or forced does not agree with this philosophy. Casual sex desires people as a means to an end and only sees the person as an object.
Also, forced sex uses coercion and deceit.
In Kantian philosophy, marriage provides a mutually respectful environment between the parties involved, and where dignity is attached to sex.