Ethos Education

Kant’s Objection to the Ontological Argument

Alevel Kant obj

coverThis A Level RE lesson uses a free downloadable clip from Arguments For The Existence of God published by Oxford University Press.

It is designed to support teaching of the following modules in the new exam specifications:

  • AQA: Component 1 (Section B)
  • EDEXCEL: Paper 1 (1.3)
  • OCR: Philosophy of Religion Paper 1 (Section B)
  • WJEC: Component 2 (AS) (Theme 1)

For this lesson you will need to download:

DOWNLOAD Kant’s Objection to the Ontological Argument:  mp4 (high-res)mp4 (low-res) / wmv / (help) (2 min 27 s)

graphic of Kant obj ont worksheet1 graphic of Kant obj ont worksheet2

Before you teach the lesson:

please complete surveyRead this professional development background material, or book an online masterclass on this area of philosophy.

The argument

  • Kant argues that the statement ‘God does not exist’ is not self-contradictory.
    • Some statements do contradict themselves (e.g. a self-contradictory statement such as ‘a bachelor is a married man’).
    • But the denial of something isn’t a contradiction. It’s like deleting a sentence; if you’ve deleted it, there’s nothing left to be self-contradictory.
    • Therefore, the denial of God’s existence isn’t self-contradictory. And because the Ontological Argument rests on God’s non-existence being self-contradictory, it is not sound.
  • Kant argues that existence is not a predicate.
    • A predicate is something that adds to the essence of a thing. For example, in the statement ‘the plant is green’ the word ‘green’ is a predicate.
    • The concept of something existing does not change our concept of the thing itself, just the world in which it now exists.
    • Therefore, according to Kant, existence is not a predicate. And if it’s not a predicate, it can’t be a perfection. Thus, God can be defined as perfect whether he exists or not.

Useful stories

  • Kant was born in Königsberg (Prussia) to Johann Georg Kant, a harness maker, in 1724.
  • Kant managed to climb the University ranks using his exceptional mind, first publishing works on Science, then later moving on to Philosophy. His work was at one time censored by Frederick William II of Prussia because of his view that religion is a purely moral system. But he outlived the King and continued writing until his final illness and death in 1804.

Background reading

enquire masterclass

Lesson Plan

please complete surveyUse (or adapt as appropriate) this plan for your lesson.

Learning Objectives

  • Understand Kant’s two criticisms of the Ontological Argument.
  • Evaluate these criticisms.


  • Watch the video Kant’s Objection to the Ontological Argument (preview and download above).
  • Clarify the argument with the students. Ask them to express it back to you.

Main Activities

  • Hand out Worksheet 1 and read through the passages as a class, clarifying points as you go.
    • Ask the students to work through the questions.
    • Feedback the students’ answers.
  • Lead this on to a student Q&A. Let them ask questions, and also pose some yourself:
    • What is the difference between Kant’s first and second objections?
    • In the case of the first objection:
      • What makes something self-contradictory?
      • If you deny the existence of something that ‘must be’, is that self-contradictory?
    • In the case of the second objection:
      • Is existence a predicate?
      • What stops something from being a predicate?
  • If appropriate, show again the video Kant’s Objection to the Ontological Argument (preview and download above).
  • Hand out Worksheet 2 and read through the passage as a class, clarifying points as you go. Make it clear that this is a response to the second objection.
    • Ask the students to work through the questions.

Evaluation of Learning

  • Ask students to present their responses in small groups.
  • Encourage debate between students who disagree.
  • If all students agree, split into two sides and allocate beliefs.
  • Moderate the debate and give students positive feedback about their knowledge and arguments.

See also:

Alevel Aquinas

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