Final answer:
The principle of universalizability is true and aligns with Kant's philosophy where moral principles should be applicable universally in relevantly similar situations.
Step-by-step explanation:
The principle of universalizability states that a moral principle or rule that applies in one situation must apply in all other situations that are relevantly similar. This statement reflects the universality of moral principles as envisioned by Enlightenment philosopher Immanuel Kant. According to Kant's philosophy, particularly his conception of the categorical imperative, one should only act according to maxims that can be willed to become universal laws. These maxims should be such that they can be applied to all rational beings without contradiction. The concept differs from the theory of Normative Ethical Relativism, which argues that moral standards vary across different cultures and should not be universally applied.
Kant's principle of universalizability can be summarized by his formula of universal law: 'Act only according to that maxim through which you can at the same time will that it become a universal law.' Therefore, the statement given is true; the principle of universalizability does indeed require that a moral rule applicable in one situation should apply to all relevantly similar circumstances.