Application of the Never As a Means Only Form to  the Lying Promise Example

""Act in such a way that you treat humanity, whether in your own person or in the person of another, always at the same time as an end and never simply as a means" (Kant in Solomon and Martin, 298).

Using as a Means Only: By making a lying promise the liar uses the person lied to as a means only or merely as a means. The liar does not treat the person as a rational being, rather than a thing.  Rational beings are ends-in-themselves, not mere means.

A Rational Being Could Not Consent.  A rational being could not consent to being treated in this manner: "For the man whom I want to use for my own purposes by such a promise cannot possibly concur with my way of acting toward him and hence cannot himself hold the end of this action. (Kant in Solomon and Martin, 299). 

Strict (Perfect) Duty to Others

Parallel Examples: Stealing or cheating on an exam.

Immanuel Kant, Grounding for the Metaphysics of Morals. 1785.  Excerpts in Morality and the Good Life: An Introduction to Ethics through the Classical Sources. 4th ed. Eds. Robert C. Solomon and Clancy W. Martin. Trans. James W. Ellington. Boston: McGraw-Hill, 2004. 262-311.