Kant's categorical imperative is unrealistic. For example, prohibiting lying under all circumstances, even if it was to save a life, or basically ascribing to an imperative, to an 'ought,' without a purpose. Clearly, Kant's deontology is so far removed from human nature which relies on purposes, goals, and ambitions. Rand saw this and rightfully ascribed self-interest as the moral imperative, and not some vague 'ought.'