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Course 14 · Lesson 2.3

Kant: existence is not a real predicate

10 minute read

Lessons in this course

Course 14 outline

Module 1: Arguments, Existence and Necessity

  1. What natural theology attempts and what it does not
  2. Necessary and contingent existence
  3. How to read and test an argument for God
  4. Philosophy of religion today: a map of the field

Module 2: The Ontological Argument

  1. Anselm and the argument of the Proslogion
  2. Gaunilo and the perfect island objection
  3. Kant: existence is not a real predicate
  4. What the ontological argument would show if it worked

Module 3: Cosmological Arguments

  1. Aquinas: the first three ways
  2. Infinite regress: what is the problem?
  3. Leibniz, the principle of sufficient reason and the argument from contingency
  4. Objections: the brute fact reply and the fallacy of composition

Module 4: The Kalam Cosmological Argument

  1. The kalam tradition: Philoponus, al-Ghazali and Bonaventure
  2. The modern argument: whatever begins to exist has a cause
  3. Did the universe begin? Philosophy and cosmology
  4. Objections and replies, and what follows about the cause

Module 5: Teleological and Fine-Tuning Arguments

  1. From Aquinas’s fifth way to Paley’s watch
  2. Hume and the Dialogues Concerning Natural Religion
  3. Darwin and the change in the design argument
  4. The fine-tuning argument: what is claimed and what is debated
  5. The multiverse and other replies

Module 6: The Moral Argument and Divine Hiddenness

  1. The moral argument: Kant, Lewis and contemporary forms
  2. The Euthyphro question and moral realism without God
  3. Evolution and moral knowledge
  4. The argument from divine hiddenness and Christian replies

Module 7: Contemporary Modal Arguments and Evaluation

  1. Possible worlds and modal logic in plain language
  2. Plantinga’s modal ontological argument
  3. Assessing the modal argument: what it needs and what it shows
  4. Weighing the arguments together, and what none of them prove

All courses

Program / Course 14: Arguments for the Existence of God / Lesson 2.3

What you will learn

  • Explain Kant’s claim that existence is not a real predicate.
  • Use the example of the hundred thalers to illustrate it.
  • State Kant’s second point about the contradiction in denying a necessary being.
  • Describe the replies of modern defenders of the ontological argument.

The big idea

Immanuel Kant (1724 to 1804) gave the most famous objection to the ontological argument. He held that existence is not a real predicate, meaning that saying a thing exists does not add a feature to the concept of the thing. Anselm’s argument treats existence as a perfection that makes a being greater. If Kant is right, the argument starts from a mistake. Defenders reply that Kant’s point does not touch the form of argument built on necessary existence.

Key terms

Predicate
What is said about a subject in a sentence, such as is red or is tall.
Real predicate
Kant’s term for a feature that adds to the content of a concept, such as being heavy. He denied that existence is one.
Concept
An idea that applies to a kind of thing, such as the concept of a dog.
Analytic statement
A statement whose truth follows from the meanings of its terms, such as all bachelors are unmarried.
Synthetic statement
A statement that adds information not contained in the meaning of the subject, such as the table is brown.
Thaler
A silver coin used in Kant’s time. Kant uses a hundred thalers as his example.
Critique of Pure Reason
Kant’s major book of 1781 (revised 1787), in which he discusses the ontological argument in the section on the ideal of pure reason.

Background

Kant gave the ontological argument its name. He used it for any argument that proceeds from the concept of God alone. He believed that no argument for God from pure reason could succeed, and he devoted a section of the Critique of Pure Reason to showing why the ontological argument fails. Earlier philosophers such as Descartes and Leibniz had restated Anselm’s argument, and Kant has them in view as well.

Kant was himself a believer of a kind, though his own beliefs were not those of orthodox Christianity. He held that belief in God is a rational demand of the moral life, a view examined in Module 6. His criticism of the arguments was therefore not an attack on religion, in his own mind, but a clearing of the ground.

Step-by-step explanation

Step 1: What a predicate does

When a person says a dog is brown, brown adds to the description of the dog. It tells the reader something more about what kind of dog it is. Kant calls this a real predicate: it enlarges the concept. His claim is that existence does not work this way.

Step 2: The hundred thalers

Kant writes that a hundred real thalers contain no more than a hundred possible thalers. If real coins contained more, then the concept would not describe the real thing. Think of what you want when you wish for a hundred coins: the coins you want are of the same kind whether you receive them or not. What changes is whether there are any such coins in the world. Existence is the positing of the thing, not a further feature of it.

Applied to Anselm, the argument seems to say that the concept of God would be incomplete without existence. Kant replies that the concept of a being with every perfection is the same concept whether or not the being exists.

Step 3: The second point about necessity

Defenders argued that it would be a contradiction to deny the existence of a necessary being. Kant replied that a contradiction arises only when one keeps the subject and denies a predicate that belongs to it. A triangle has three angles; to keep the triangle and deny three angles is contradictory. But if you cancel both the subject and the predicate, there is no contradiction. To say there is no God removes the subject along with its attributes, and nothing contradictory remains.

Step 4: Replies from defenders

Some philosophers reply that Kant’s point, though it is true of ordinary descriptions, misses a feature of Anselm’s argument. The relevant perfection might be necessary existence, which is not mere existence. Others observe that Kant’s claim itself is disputed in modern logic. Gottlob Frege and Bertrand Russell developed a view in which existence is a property of concepts, not of objects, which supports Kant. But other philosophers, such as Plantinga, argue that the modal form of the ontological argument does not depend on treating existence as a predicate of this kind.

Critics respond that necessary existence has the same difficulty in a new form, because they doubt that it names a coherent feature at all.

Step 5: Weigh the objection

Kant’s objection is regarded as strong against the simplest version of the argument. Whether it defeats the whole family of arguments is disputed. A careful reader notes which version is in view each time and does not suppose that a point against one automatically refutes another.

  1. Does saying that a thing exists tell you more about what the thing is?
  2. What is the difference between the thalers in your imagination and those in your pocket?
  3. Is a unicorn that exists a different concept from a unicorn that does not?
  4. What is Kant’s reply to the claim that denying God is a contradiction?
  5. Could necessary existence be a real predicate, even if mere existence is not?
  6. Why might Kant’s point against the argument matter to a believer?

Examples

Describing a house

An architect describes a house with three bedrooms, a red door and a garden. The description is complete whether the house is built or not. Building it does not add a fourth feature to the plan. It makes the plan true of something. This is the idea behind Kant’s thaler.

A triangle and its angles

To say that a triangle exists and does not have three angles is a contradiction. To say that there is no triangle at all is not a contradiction. Kant treats the claim that there is no God in the second way.

The census

If a census taker is told to count real people and not merely possible people, she does not add a column for existence. She counts the people. This is an everyday way of seeing why existence seems to work differently from height or age. (A constructed example.)

Different perspectives

Catholic

Catholic thinkers have often agreed with Kant that the ontological argument fails, though for different reasons. Aquinas rejected it before Kant. Some twentieth-century Catholic philosophers have held that Kant’s wider claim, that reason cannot reach God, is false and have defended other arguments.

Orthodox

Orthodox theologians usually do not rely on the argument, and see Kant’s critique as one more sign that God is not reached by the concept of a being. They are also critical of Kant’s view that God cannot be known, since the tradition holds that God is known in the divine energies.

Protestant

Kant belonged to a Lutheran Pietist background and his influence on Protestant theology was great. Schleiermacher and others took religion out of metaphysics. Evangelical and Reformed philosophers such as Plantinga reply that the modal argument escapes Kant’s objection.

Scholarly views

Scholars note that Kant was responding mostly to Leibniz and Descartes, not to Anselm directly. Many hold that his criticism applies to some versions of the argument and not to others. Whether existence is a predicate is still debated in logic and metaphysics.

Skeptical views

Skeptics treat Kant’s objection as decisive. They say that no argument can bring a being into existence from a definition, and that the later modal versions merely move the same problem to the premise that God is possible.

Why it matters

Kant’s objection is a model of how to criticize an argument at its root. It also shows how a philosopher can reject an argument without rejecting its conclusion. Understanding it will prepare you for the modern modal arguments in Module 7, which were designed with this objection in mind.

Common misunderstandings

Misunderstanding: Kant said that God does not exist.

Correction: Kant did not deny God. He held that reason cannot prove God’s existence and that belief in God is a postulate of morality.

Misunderstanding: Kant refuted all arguments for God in one stroke.

Correction: Kant intended to, but his critique of the cosmological and teleological arguments rests on further claims that are also disputed.

Misunderstanding: Existence is not a predicate means that nothing really exists.

Correction: It means only that existence is not an added feature in a description. Kant had no doubt that things exist.

Misunderstanding: Anselm’s argument is exactly the one Kant refuted.

Correction: Kant has the later forms in mind. Some scholars argue that Anselm’s chapter 3 argument is not touched by the objection.

Knowledge check

What does Kant mean by saying existence is not a real predicate?

He means that saying a thing exists does not add a feature to the concept of the thing. A hundred real thalers contain no more than a hundred possible ones, in content. Existence says that there is something answering to the concept. If it added content, the real object would not match the concept that was in mind.

How does this objection apply to the ontological argument?

The argument supposes that existence is a perfection that makes the greatest being greater. If existence is not a feature that adds to a concept, the concept of the greatest conceivable being is the same whether or not it exists. The step from the concept to the real existence then fails.

What is Kant’s point about necessary beings and contradiction?

A contradiction arises when you keep a subject and deny a predicate that belongs to it, like a triangle without three angles. But if you remove the subject altogether, as in saying there is no God, no contradiction remains. So the claim that denying God is contradictory does not follow, even for a necessary being.

How do modern defenders reply?

Some say that necessary existence is a different and richer notion than mere existence and may be a perfection. Others, like Plantinga, build modal versions that do not treat existence as a predicate. Critics respond that these versions need the premise that God is possible, which is the matter in dispute. The exchange continues.

Think it through

  1. Does Kant’s example convince you that existence adds nothing to a concept?
  2. Does it matter whether existence is a predicate if the argument can be reworded?
  3. How might a believer who agrees with Kant here still hold that God exists?
  4. Where in the argument do you think the weakest point lies after reading Kant?

Independent assignment

Kant’s thalers

In your own notebook, write 300 to 450 words. Explain Kant’s example of the hundred thalers in your own words, with a different example of your own. Then write a paragraph stating what a defender of the ontological argument might say in reply, and a paragraph saying which side you find stronger and why. Do not send this to anyone.

Further study