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Course 14 · Lesson 7.4

Weighing the arguments together, and what none of them prove

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 7.4

What you will learn

  • Compare the five families of argument by their premises, strengths and weaknesses.
  • Explain the idea of a cumulative case and its limits.
  • State what the arguments, taken together, do not establish.
  • Write a fair evaluation of an argument and defend one against its best opponents.

The big idea

Each argument in this course has a premise that is disputed. A cumulative case holds that several arguments, each of modest strength, may support the same conclusion more strongly together, and some philosophers defend this approach. Others reply that weak arguments do not add up to strong ones if they share assumptions. Whatever a student concludes, none of the arguments reaches the Trinity, the incarnation or the resurrection. A fair evaluation says what each argument shows, what it needs, and what it leaves open.

Key terms

Cumulative case
A case made of several independent considerations that together support a conclusion more than any alone.
Independent evidence
Evidence whose force does not depend on the same assumptions as other evidence.
Bayesian reasoning
A way of reasoning about evidence in which one’s confidence in a hypothesis is updated by how well it predicts what is observed.
Prior probability
How likely a hypothesis is thought to be before considering the evidence at issue.
Theism
Belief in one God, the personal creator and sustainer of all.
Religious experience
An experience taken by the person who has it to be of God or of the sacred.
Fideism
The view that faith neither needs nor should seek rational support.

Background

Richard Swinburne developed the best-known cumulative case in The Existence of God (1979, revised 2004). He argues that cosmological, teleological, moral and other considerations each raise the probability of theism, and that together they make it more likely than not. J. L. Mackie, in The Miracle of Theism (1982), argued from the other side that the considerations fail individually and that their combination does not help. Their exchange remains a model of careful disagreement.

Others take different routes. Plantinga holds that belief in God needs no argument. Hart argues from the character of being, consciousness and bliss. Pascal and Kierkegaard warn against turning faith into a conclusion of reasoning. These views are not refuted by the arguments studied here, and they remind a student that the arguments are only one way of thinking about God.

Step-by-step explanation

Step 1: A summary of the five families

The ontological argument claims that the concept of a maximally great being implies its existence. Its weak point is the premise of possibility. The cosmological arguments argue from contingency or causation to a necessary or first cause. Their weak point is the principle of sufficient reason or the claim that a series cannot be infinite. The kalam argument argues from a beginning to a cause. Its weak points are the beginning of the universe and the step to a personal cause. The teleological and fine-tuning arguments argue from order and the conditions for life. Their weak points are probabilities and rival explanations. The moral argument argues from objective morality. Its weak point is whether morality needs God.

Step 2: Do they add up?

Defenders of the cumulative case say that the arguments rely on different evidence, so they are partly independent. If each makes theism somewhat more probable, together they make it much more so. Critics reply that three weak arguments do not make a strong one. Further, the arguments often share the assumption that explanation must end in a mind, and an objector who rejects it rejects all. They add that the prior probability of theism matters a great deal, and that people differ about it for reasons that arguments cannot settle.

Step 3: The hiddenness argument as counterweight

A fair weighing includes the case against theism. The argument from hiddenness and the problem of evil, which belongs to a related course, are the strongest. A cumulative case for God should be compared with a cumulative case against, in which evil, hiddenness, religious diversity and the success of natural explanations count. Philosophers who weigh both sides reach different conclusions, which shows the question is not settled.

Step 4: What none of them prove

Even in the best case, these arguments establish a being or ground that is powerful, intelligent or necessary, and perhaps good. They do not establish the Trinity, that God became a man in Jesus of Nazareth, that Jesus rose from the dead, or that the Church speaks for God. Christian claims rest on the testimony of Scripture, the history of Jesus and the life of the Church. Natural theology is, at most, a preparation for that testimony, as Aquinas said. A person who thinks the arguments fail is not thereby excluded from considering the gospel, and a person who thinks they succeed has not yet considered it.

Step 5: How to judge fairly

A fair evaluation follows a pattern. State the argument in numbered steps. Name the premise an opponent will deny. Give the best reason for it and the best reason against. Say what the argument would show if it worked. Say how confident you are, and why. A student should be able to defend any one of the arguments against its best opponents, and equally to state why a reasonable person might reject it.

  1. Which family of argument seems strongest to you, and why?
  2. Can several weak arguments make a strong case?
  3. How much does your starting view affect how you judge the arguments?
  4. What does the case against theism add to the weighing?
  5. What would you still want to know after the arguments have been weighed?
  6. How would you describe the arguments to a friend, fairly?

Examples

Swinburne and Mackie

Swinburne argued that the arguments combined make theism more probable than not. Mackie argued that they fail separately and together. Each wrote to answer the other’s work, and each treated the other fairly. Their exchange is often recommended as an example of philosophical debate.

Three witnesses

If three witnesses independently report the same event, their agreement is stronger than any one report. But if they all heard it from the same source, their agreement adds little. The question for the cumulative case is which picture fits the arguments for God.

Aquinas’s own limit

Aquinas gave the Five Ways in one article, and then spent the following questions on what God is like and the rest of the Summa on the Trinity, Christ and the sacraments, which he held can be known only by revelation. His own work models the relation between the arguments and the faith.

Different perspectives

Catholic

The Catholic Church teaches that God can be known with certainty from created things by natural reason (Vatican I, Dei Filius), and also that this knowledge is not sufficient for salvation, which requires revelation and faith. Catholic thinkers value the arguments as preambles, not as the grounds of faith.

Orthodox

Orthodox theology treats the arguments with reserve. It holds that God is known by communion and that faith comes through encounter with Christ in the Church. Arguments may clear obstacles, but they do not lead to the living God. This is a consistent emphasis from the Fathers to the present.

Protestant

Protestants range from the evidential approach of Swinburne and Craig, to the Reformed epistemology of Plantinga, who holds that belief in God is properly basic, to the Barthian view that natural theology is unnecessary or harmful. All agree that saving faith comes by hearing the gospel (Romans 10:17).

Philosophical views

Surveys of professional philosophers show that most are not theists, and a notable minority are. Opinions on the arguments vary, with the cosmological and fine-tuning arguments receiving the most attention. There is no consensus that any argument succeeds or that all have failed.

Skeptical views

Skeptics hold that none of the arguments gives good reason to believe, and that the cumulative case is no stronger than its parts. Many add that the success of natural explanations has reduced the need for hypotheses about God, though a few, like Nagel, find that naturalism leaves important features of the world unexplained.

Why it matters

A student who finishes this course should be able to speak fairly about the arguments with a believer, a skeptic or an undecided friend. The aim was not to settle the matter, but to equip the student to examine it, to resist exaggerated claims and to see the real questions.

Common misunderstandings

Misunderstanding: If the arguments fail, belief is irrational.

Correction: Many philosophers, including Plantinga, hold that belief in God can be rational without arguments, as belief in other minds is.

Misunderstanding: If the arguments succeed, Christianity is proved.

Correction: They would support a God of some kind. The central Christian claims depend on other evidence.

Misunderstanding: Philosophers have settled the question.

Correction: Professional opinion remains divided, and each argument has living defenders and critics.

Misunderstanding: Weighing arguments means splitting the difference.

Correction: It means judging each premise honestly. The result may favor one side strongly.

Knowledge check

What is a cumulative case?

It is a case in which several independent considerations together support a conclusion more than any alone. Swinburne’s case for theism combines cosmological, teleological, moral and other arguments. Critics reply that weak arguments that share assumptions do not become strong by combination, and that the result depends heavily on prior probabilities.

Name the disputed premise in each family of argument.

In the ontological argument it is the possibility of a maximally great being. In cosmological arguments, the principle of sufficient reason or the impossibility of an infinite regress. In the kalam argument, the beginning of the universe. In the design arguments, the probabilities of fine-tuning. In the moral argument, the claim that objective morality needs God.

What do the arguments not establish?

They do not establish the Trinity, the incarnation, the resurrection of Jesus or the authority of the Church. At most they support a being of power, intelligence and perhaps goodness. Christian claims rest on revelation and historical testimony, and Aquinas himself held that these cannot be reached by reason alone.

Why is a fair weighing incomplete without the case against theism?

Because the arguments for God must be compared with the strongest considerations on the other side, such as the problem of evil, divine hiddenness and the success of natural explanations. Judging only one side would give a distorted picture. Philosophers who weigh both reach differing conclusions, which shows that the question remains open.

Think it through

  1. What did you think at the start of the course, and what do you think now?
  2. Which argument would you most like to see defended better?
  3. How should the limits of the arguments shape the way a Christian speaks of them?
  4. What is the next question you want to study?

Independent assignment

Evaluate three arguments and defend one

In your own notebook, write 700 to 1,000 words. Choose three arguments from the course. For each, write it in numbered steps, name the contested premise, and give the best objection and reply. Then choose one and write a defense of it against its best opponents, in a form its supporters would accept. End by comparing your result with the page you wrote in the first lesson. Do not send this to anyone.

Further study