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Understanding Immanuel Kant

Immanuel Kant pencil drawing

Understanding Immanuel Kant is the fourth philosophy study guide in the Smart Student Guides series. 


After his retirement in 2016, Professor Laurence Houlgate wrote these books to help beginning philosophy students understand the classics of philosophy.  During his 51 year of teaching, he found that help was especially needed as his students struggled to understand Kant's notoriously difficult Grounding for the Metaphysics of Morals.

The struggle to understand is worth it.  Professor Henry Allison, the leading commentator on Kant's work, said of Grounding that it is "the single most important work in modern moral philosophy."

But It is also one of the most difficult books to comprehend, especially for beginning philosophy students. Understanding Immanuel Kant makes Kant accessible to students while at the same time showing why his writings have had such a powerful influence on philosophical ethics.

Houlgate's study guide is not a scholarly monograph on Kant, nor is it a bare-bones outline of Kant's writings. Instead, the book gives the reader an interpretation of Kant in ordinary language, explaining the technical words Kant uses ("analytic," "synthetic," "categorical imperative," "autonomy of the will") and using examples of moral problems drawn from everyday life. The book also shows how Kantian ethics differs from the theories of the other great philosophers represented in the series (Plato, Locke, Hobbes and Mill).

Each chapter concludes with questions for thought and discussion and within these questions students will find many topics that can be pursued in term papers.

Here is a sample from Understanding Immanuel Kant:

I will use Kant’s argument for the claim that it is always wrong (a violation of moral duty) to make a lying promise.  Kant’s example is about a poor man who is desperate for a loan to pay his debts but realizes that the only way he can convince someone to loan him money is to make a promise to pay back the loan, even though he knows that he will never able to do this.  Kant tells us that even if the person loaning the money is a billionaire and the man who needs the loan is a dirt-poor single parent of five hungry children, it would be morally wrong for this man to make a lying promise as a means to convince the billionaire to make the loan. 

Here is Kant’s argument in the valid form we have previously called  hypothetical syllogism:


1. If a man who needs a loan makes a lying promise to pay back the loan, then he is acting on a subjective maxim (personal rule) that says “Whenever I believe myself to be in need of money, I will borrow money and promise to pay it back, although I know I can never do so” (Grounding, 402).  [We will refer to this as maxim BP]

2. If anyone acts on maxim BP, then they will (endorse) a universal law that says that anyone in similar circumstances can behave in the same way, that is, “anyone believing themself to be in difficulty could promise whatever they please, with the intention of not keeping the promise.” (id.) [We will refer the universal law as ULBP]

3. If one wills ULBP, then no one would believe that a promise made by others would be kept [We will refer to this as a false promise or FP].

4. If FP, then “promising itself and the end to be attained thereby would become quite impossible” (id.).

5. If promising itself and the end to be attained thereby is made impossible, then the maxim BP “cannot be made a universal law.”


Kant completes the argument with a three step syllogism:

6. If a maxim cannot be made a universal law, then it is morally wrong to act on it.

7. The maxim BP cannot be made a universal law.

8. Therefore, it is morally wrong to act on the maxim BP.


We can declare the argument valid.  But is it sound?  Are the premises true? 

You might want to take a look at premise 2.  Kant assumes that if you act on a personal rule, then you are committed to a universal rule that applies to everyone in similar circumstances.  For example, if I say that it was wrong for me to take my roommate’s car for a short trip out of town without his permission, then I have committed myself to the universal rule that it would be wrong for anyone to do this.  It would be a contradiction for me to say “It was wrong for me to do that, but it might not be wrong for you do it.”  It would not be a contradiction only if the circumstances are different in your case, for example, you needed to take a seriously injured friend to the hospital.

[Get your copy now.  Click on the book cover image above]

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