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Course 14 · Lesson 1.2

Necessary and contingent existence

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 1.2

What you will learn

  • Define contingent and necessary existence with examples.
  • Explain why the distinction is central to the ontological and cosmological arguments.
  • Distinguish a being that depends on something else from one that exists by its own nature.
  • State the objection that the notion of a necessary being is confused or unproven.

The big idea

A contingent thing exists, but it might not have existed: it depends on causes and conditions, and the world could have gone otherwise. A necessary being, if there is one, exists in a way that could not have failed. Many arguments for God try to show that the contingent things in experience cannot be the whole story and that something necessary must lie behind them. Critics ask whether the idea of a necessary being makes sense, and whether anything exists necessarily.

Key terms

Contingent
Describing something that exists but could have failed to exist, or could have been otherwise.
Necessary
Describing something that could not have failed to exist, or a statement that could not have been false.
Aseity
A Latin-derived word meaning existence from oneself. A being with aseity depends on nothing else for its existence.
Dependence
The relation in which one thing exists or is what it is because of something else.
Logical possibility
What can be described without contradiction. A round square is not logically possible.
Metaphysics
The part of philosophy that studies what exists and what its basic features are.
Abstract object
Something often said to exist without being in space or time, such as a number. Some philosophers say such things exist necessarily.

Background

The pair of words contingent and necessary comes from Aristotle and was developed by medieval thinkers, including Avicenna, a Muslim philosopher whose work Aquinas read closely. Avicenna divided things into those that might or might not be and one that must be. The idea runs through Aquinas’s Third Way, through Leibniz and into modern work on possible worlds.

The distinction is easiest to grasp through examples. You exist, but you might not have: your parents might never have met. A particular mountain exists, but there might have been no mountain there. By contrast, many philosophers hold that the statement “two plus two equals four” could not have been false. Whether anything that exists, as opposed to a truth, is necessary is exactly what the arguments dispute.

In Christian theology the idea corresponds to a claim about God’s aseity. The creeds speak of God as maker of all things seen and unseen, and the tradition has taught that creatures depend on God for their existence while God depends on nothing. Philosophers who build arguments from necessity are therefore making, in careful language, a claim Christians had long made in other language.

Step-by-step explanation

Step 1: Test things with the question “could it have failed to exist?”

Take a tree, a person or a planet. Can you imagine, without contradiction, that it did not exist? Yes. These are contingent. Now take a triangle’s property of having three sides, or the fact that no one is both married and unmarried at once. Here the supposed failure seems impossible. These are necessary truths.

Step 2: Notice what contingent things need

A contingent thing does not explain its own existence. Its parents, the soil, the sun or a long chain of events does. It has a cause, or at least conditions that make it possible. If everything met in experience is contingent, a natural question arises: what explains the whole collection?

The cosmological arguments, studied in Module 3, begin from just this question. They ask whether a series of contingent things can explain itself or whether something that does not depend on anything must be involved.

Step 3: See the different senses of necessary

Philosophers distinguish several senses. A statement is logically necessary if its denial is a contradiction. A thing is metaphysically necessary if it exists in every possible world, a phrase explained in Module 7. A thing is causally necessary if it must occur given the laws of nature. An argument that slides from one sense to another can look convincing without being so.

The kind relevant to God is usually that God is a being whose existence is not caused or dependent. Some philosophers add that God’s existence is metaphysically necessary, that is, could not have failed.

Step 4: Hear the objections

Hume and Kant, and many later philosophers, doubted that existence can be necessary. Hume argued that whatever can be conceived as existing can also be conceived as not existing, so no being’s non-existence is contradictory. Defenders reply that this treats what can be imagined as the test of what is possible, which is a weak test.

Another objection is that the universe itself, or the laws of physics, or mathematical truths, might be the necessary or ultimate thing, with no need to go beyond them. Believers reply that these seem to lack the features of a necessary being, for instance, the physical universe appears to be a collection of contingent things. The debate is open.

Step 5: Keep the distinction in view as you read

Each time a later argument appeals to a necessary being, stop and ask: in which sense of necessary? Does the argument show it, or assume it? Writing the answer in your notebook will save you from many confusions.

  1. What is one thing you are sure exists contingently, and what might have prevented it?
  2. Can you think of something that exists and could not have failed to exist? What makes you think so?
  3. Is a number a necessary being? What does your answer imply about the word being?
  4. If every individual thing depends on something else, does the whole collection need an explanation?
  5. What is the difference between not being able to imagine something and its being impossible?
  6. Why might believers want God to be necessary rather than merely very powerful?

Examples

A candle flame

A flame exists only while the candle burns and the air supports it. Remove either and it is gone. It is an everyday picture of dependence. The question for later arguments is whether the whole world is like the flame, depending on something, or is self-standing.

A mathematical truth

Many philosophers say the truth that there are infinitely many prime numbers could not have been false in any possible circumstances. That is a necessary truth. Whether it is also a necessary object, an existing number, is a further, disputed question. (This is a standard textbook example.)

Avicenna’s idea

Avicenna argued that anything whose existence is only possible needs a cause to make it actual, and that the chain of such causes must lead to a being whose existence is necessary by itself. Aquinas adapted this reasoning in his Third Way.

Different perspectives

Catholic

Catholic theology following Aquinas teaches that in God essence and existence are the same: God is subsistent being itself, and so exists necessarily, while creatures receive their being. This teaching is part of the tradition’s philosophy but is not a defined article of the creed in those technical words.

Orthodox

Orthodox theology teaches that God is the uncreated, without beginning or dependence, and that all else is created and sustained by God. Writers such as Gregory Palamas are cautious about applying human categories to God’s essence, and prefer to say God is beyond being in the sense of beyond all that creatures are.

Protestant

Protestant confessions such as the Westminster Confession describe God as having all life, glory and goodness in and of himself, independent of creatures. Reformed and evangelical philosophers like Plantinga defend the idea of a necessarily existing God. Some Protestant theologians, following Barth, prefer to speak of God from revelation and not from metaphysical categories.

Hume and the empiricist critique

Hume held that existence claims can only be established by experience, never by reasoning from ideas, and so the notion of a being whose non-existence is inconceivable is empty. This view remains influential among philosophers who prefer to build knowledge from evidence.

Contemporary secular views

Some philosophers allow that necessary existence is coherent but hold that physical reality, laws of nature or abstract objects could fill the role. Others, called naturalists, say it is reasonable to stop at the universe as a brute fact. Others think the word necessary has no clear application outside logic and mathematics.

Why it matters

Almost every argument in this course depends on the idea of a being that exists by its own nature. If the idea is confused, the arguments built on it fall. If the idea is sound, it explains why the arguments take the form they do. Learning the distinction now makes the rest of the course much easier to follow.

Common misunderstandings

Misunderstanding: Contingent means uncertain or accidental.

Correction: In this context contingent only means dependent and not necessary. A contingent thing may be very reliable, such as the sun. The point is that it might not have existed.

Misunderstanding: A necessary being is just one that is very old or very powerful.

Correction: Necessity is not about age or strength. It means being such that non-existence is impossible or that existence depends on nothing.

Misunderstanding: Everything that can be thought of as existing could also not exist, so necessity is empty.

Correction: That is Hume’s view, and it has defenders. But it assumes that what is imaginable shows what is possible, which many philosophers deny.

Misunderstanding: Necessary existence has been proven by this distinction.

Correction: The distinction only lays out the terms. Whether anything is necessary is the question the arguments try to answer.

Knowledge check

What is the difference between a contingent and a necessary being?

A contingent being exists but could have failed to exist, and depends on causes or conditions. A necessary being exists in a way that could not have failed, or depends on nothing else for its existence. Most things in ordinary experience are contingent. Whether anything is necessary is what the arguments try to settle.

Why does the distinction matter for the cosmological argument?

Cosmological arguments begin from contingent things and ask what explains them. If each depends on another, one may ask what explains the whole series. Defenders say the answer must be something that does not itself depend, a necessary being. Without the distinction the argument could not even be stated.

Name two different senses of necessary.

Logical necessity means the denial is a contradiction, as with a married bachelor. Metaphysical necessity means existing in every possible world. Causal necessity means required by the laws of nature. An argument that moves from one sense to another without saying so may be misleading.

What was Hume’s objection to necessary existence?

Hume held that whatever can be conceived as existing can also be conceived as not existing, so no existence claim is contradicted by its denial. He concluded that the idea of a being whose non-existence is inconceivable is empty. Defenders reply that imaginability is not a good test for possibility.

Think it through

  1. What do you take to be the best candidate for a necessary being, and why?
  2. Does the fact that the universe exists seem to you to call for explanation?
  3. Why might a person be satisfied to stop asking why at the universe?
  4. Does the idea of a necessary God help or hinder a relationship with God?

Independent assignment

Sorting what exists

In your own notebook, write 300 to 400 words. List ten things, including a person, a planet, a number, a law of nature, an idea, an event and God. For each, write whether it is contingent or necessary in your view and give a one-sentence reason. Then write a paragraph on the item you were least sure about. Do not send this to anyone.

Further study