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Course 14 · Lesson 4.3

Did the universe begin? Philosophy and cosmology

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 4.3

What you will learn

  • State the philosophical arguments against an infinite past and the objections to them.
  • Describe the main scientific evidence that the observable universe had a beginning.
  • Explain why the Big Bang is not the same as a proof of an absolute beginning.
  • Name the main alternative models and the status of the debate.

The big idea

The second premise of the kalam argument says that the universe began to exist. Defenders give two kinds of reason. Philosophical arguments say that an actual infinite past is impossible. Scientific arguments cite the expansion of the universe and theorems about the past of expanding spacetimes. Critics reply that infinities are consistent in mathematics, that the Big Bang describes a hot, dense early state and not necessarily an absolute beginning, and that quantum models may avoid a first moment.

Key terms

Big Bang
The scientific model according to which the observable universe expanded from an extremely hot, dense state about 13.8 billion years ago.
Singularity
A point at which a theory predicts infinite density and breaks down. It is a sign that the theory is incomplete, not necessarily that there was a real point.
Cosmic microwave background
Faint radiation from the early universe, discovered in 1965, which supports the Big Bang model.
Borde-Guth-Vilenkin theorem
A 2003 result stating that any universe that has on average been expanding cannot be extended into the infinite past, though it does not say what happened before.
Steady state theory
A rival model, popular in the 1950s, in which the universe has no beginning and new matter appears continually. It was abandoned after the discovery of the microwave background.
Cyclic or bouncing model
A model in which the universe goes through repeated expansions and contractions.
Quantum gravity
A not-yet-complete physical theory that would combine general relativity and quantum mechanics.

Background

Until the twentieth century most scientists thought the universe was eternal. In the 1920s Georges Lemaitre, a Belgian Catholic priest and physicist, proposed that the universe is expanding from a primeval state. Edwin Hubble’s observations supported expansion. Some physicists at first disliked the idea because it seemed to resemble the doctrine of creation. Fred Hoyle, who coined the name Big Bang as a joke in a 1949 radio talk, defended the steady state theory for decades. The discovery of the microwave background in 1965 convinced most scientists.

Pope Pius XII, in 1951, spoke of the Big Bang as consonant with creation, and Lemaitre himself objected, believing that science should not be used to prove theology. His caution is shared by many today. The question of the philosophical and theological meaning of the Big Bang remains debated.

Step-by-step explanation

Step 1: The philosophical argument

The first argument says that an actual infinite cannot exist in reality, so a past with infinitely many events cannot exist. A second argument says that even if infinities exist, one cannot be formed by adding one member after another, and the past is formed in that way. Craig supports these with Hilbert’s Hotel and with questions about counting.

Critics reply that the mathematics of infinite sets is consistent and that nothing shows that the physical world cannot contain an infinity. They add that a beginningless past was not formed by adding: at any past time, only a finite number of days precede today. Defenders reply that this misses the problem of completing the series.

Step 2: The scientific evidence

The expansion of the universe, observed since the 1920s, means that running time backward the galaxies come closer together. The microwave background and the observed amounts of light elements agree with a hot early state. On standard models, the density of the early universe rises without limit about 13.8 billion years ago, which is where the equations break down.

In 2003, Arvind Borde, Alan Guth and Alexander Vilenkin proved that any universe that has on average been expanding throughout its history must have a past boundary. Vilenkin has said that all the evidence says the universe had a beginning, though he has been careful about the limits of the theorem.

Step 3: Why the Big Bang does not settle it

Physicists caution that the singularity marks the end of what the theory can describe. It may not be a true first moment. A complete theory of quantum gravity might replace it with something else. Models proposed include a bounce from an earlier contracting phase, an eternal inflating multiverse in which one region began but the whole has no beginning, and a quantum state in which time has no sharp starting point, as in Hartle and Hawking’s no-boundary proposal.

These models are speculative, and none is confirmed. The Borde-Guth-Vilenkin theorem applies to many but not all of them, and its authors note that it does not cover a past that is not expanding.

Step 4: Philosophical questions about beginning

Even if time had a first moment, philosophers ask whether the universe then began to exist in the sense the first premise needs. Some say that if time itself begins with the universe, there is no moment before at which the universe was not, so beginning in the ordinary sense does not apply. Defenders reply that the universe still has a finite past and that this is enough to ask for a cause.

Step 5: A fair verdict

The best summary is that the evidence favors a beginning of the observable universe about 13.8 billion years ago, that whether this is an absolute beginning is unsettled, and that physics cannot settle it by present means. The philosophical arguments are respected but not accepted by most philosophers. A careful believer or skeptic should avoid claiming more.

  1. Why might the idea of a beginning have troubled some scientists in the 1940s?
  2. What difference does it make that the singularity may be a sign of a failing theory?
  3. Do you find the argument from forming an infinite series convincing?
  4. Why did Lemaitre object to using the Big Bang to prove theology?
  5. What would count as evidence of an eternal universe?
  6. Does it matter for faith whether science finds a beginning?

Examples

Lemaitre and the Pope

Georges Lemaitre was both a priest and a physicist. When Pope Pius XII in 1951 praised the Big Bang as support for creation, Lemaitre is reported to have been uneasy and to have urged that science and theology keep their own methods. Historians give this account with some caution.

Hoyle’s joke

Fred Hoyle, who held the steady state theory, used the phrase Big Bang on a BBC radio broadcast in 1949 to describe the rival theory. The name stuck even though he meant it as a criticism.

A bouncing universe

In some models the universe contracts to a tiny size and then expands again, possibly repeating forever. Critics note that such models face difficulties with entropy, which would build up in each cycle, and that no observation supports them.

Different perspectives

Catholic

Catholic teaching holds that the world had a beginning in time as a matter of faith (Fourth Lateran Council). The Church’s scientists, including Lemaitre, have been cautious about identifying the Big Bang with creation. The Vatican Observatory has long taken part in cosmology.

Orthodox

Orthodox theology teaches that time was created with the world, as Augustine also taught in the West. Orthodox writers generally see no conflict with the Big Bang model and avoid tying faith to a particular physical theory.

Protestant

Evangelical apologists such as Craig and Hugh Ross use the Big Bang in support of a beginning. Other Protestants, including many scientists, caution that theology should not depend on a model that could change. The matter divides Protestants.

Scientific views

Most cosmologists accept the Big Bang as a description of the early universe and agree that standard models do not describe a first moment well. Opinions differ about whether the universe has a beginning, and many say the question is open pending a theory of quantum gravity.

Skeptical views

Skeptics such as Carroll argue that nothing in physics requires a beginning and that a universe without one is at least as plausible. They add that arguments from physics to theology are premature.

Why it matters

The kalam argument is the only classical argument that stands or falls on a claim science can speak to. Learning what the evidence says, and does not, protects against the two common errors: claiming that science has proved creation, and claiming that science has disproved it.

Common misunderstandings

Misunderstanding: The Big Bang is a proof that God created the universe.

Correction: It is a scientific model of the early universe. Whether it shows an absolute beginning, and whether a beginning needs God, are separate questions.

Misunderstanding: The Big Bang was an explosion in space.

Correction: It was an expansion of space itself. There was no empty space into which it exploded, as far as the model describes.

Misunderstanding: Scientists have shown the universe is eternal.

Correction: Several models without a beginning exist, but they are speculative and unconfirmed.

Misunderstanding: A beginning of time would be a beginning at some time.

Correction: If time itself begins, there is no earlier time. That is part of why some philosophers find talk of what caused it obscure.

Knowledge check

What is the main scientific evidence that the universe began?

The universe is expanding, so running time backward brings matter together. The microwave background radiation and the amounts of light elements agree with a hot, dense early state about 13.8 billion years ago. A 2003 theorem shows that universes that have on average been expanding must have a past boundary, though it does not say what lies before it.

Why do physicists hesitate to call the Big Bang an absolute beginning?

Because the singularity marks the point where known theory breaks down, and a theory of quantum gravity might replace it. Models such as a bounce, an eternal multiverse or a no-boundary state avoid an absolute first moment. None is confirmed, but they remain live options.

What are the philosophical arguments against an infinite past, and how are they answered?

One says an actual infinite cannot exist, another that an infinite series cannot be completed by successive addition. Critics reply that infinite sets are consistent in mathematics and that a beginningless past does not need to be completed, since every past day is a finite distance back. Defenders hold that the problem persists.

Why did Lemaitre want to keep science and theology separate?

He believed that scientific theories should be judged by physical evidence and that theology should not rest on them, since they might change. He thought using the Big Bang to prove creation risked harming faith if the theory were later revised. Many scientists and theologians share this caution.

Think it through

  1. Would your faith or doubt change if physicists proved the universe eternal?
  2. Is it wise to base a theological argument on a current scientific model?
  3. What does it mean to ask what happened before time began?
  4. Which kind of evidence, philosophical or scientific, is more persuasive to you?

Independent assignment

What science says, and what it does not

In your own notebook, write 350 to 500 words. Write two columns: what current cosmology says about the beginning of the universe, and what it does not say. Then write a paragraph on how a defender of the kalam argument and a critic would each use the same evidence. Do not send this to anyone.

Further study