Program / Course 13: Foundations of Apologetics / Lesson 3.5
What you will learn
- Follow a repeatable procedure for turning a piece of writing into a mapped argument.
- Draw simple argument maps that show premises, intermediate conclusions and the main conclusion.
- Evaluate each premise and each inferential step separately.
- Apply the procedure to a well-known apologetic argument.
The big idea
Mapping an argument means laying it out so that its parts and the links between them can be seen at a glance. The procedure has six moves: find the conclusion, list the premises, add any unstated premises, show how the premises connect, test each premise and each step, and consider objections. Using it turns a vague sense that an argument is good or bad into specific judgments about which claim holds and which does not. It also trains fairness, since the author’s reasoning must be stated before it can be criticized.
Key terms
- Argument map
- A diagram or numbered layout that shows how the premises of an argument support its intermediate and final conclusions.
- Linked premises
- Premises that must work together to support a conclusion, so that removing one removes the support.
- Convergent premises
- Premises that each support a conclusion independently, so that the conclusion is supported even if one is removed.
- Objection
- A reason to doubt a premise, a step or the conclusion.
- Rebuttal
- An answer to an objection.
- Crucial premise
- A premise on which the argument most depends, and whose truth is most disputed.
Background
Teachers of critical thinking have long used diagrams to display reasoning, and modern software exists for drawing argument maps. The paper-and-pencil method is enough for most purposes. It requires nothing more than a numbered list and some arrows.
This lesson uses a single worked example, one of the arguments often used in apologetics. It is chosen because it is short, because it has been discussed by philosophers on all sides, and because its main premise is open to dispute. The point of using it here is to practice the method, not to settle whether the argument works.
Step-by-step explanation
Step 1: Read for the conclusion, then list the premises
Read the passage once to see what it is about, and a second time to find the main conclusion. Write it at the bottom of a page. Then go through the text and list every reason offered, each as a short, plain sentence, numbered in the order given.
Do not worry about order at first. Capture the claims. A common example in the literature on moral arguments for God runs: if God does not exist, then objective moral values do not exist; objective moral values do exist; therefore God exists. The conclusion is that God exists. The premises are the first two statements.
Step 2: Add unstated premises and clarify terms
Ask whether anything is assumed but not said. In the example, the word objective needs explaining. In this context an objective moral value is one that holds whether or not any person believes it. If the terms are not defined, the premises can be read in different ways, and the argument will seem stronger or weaker than it is.
Also check for a hidden conclusion in the middle. The argument above depends on a larger claim that moral values need a foundation of a particular sort. If that claim is part of the author’s view, it can be added as a supporting premise, with the author’s own reason for it.
Step 3: Show the connections
Draw the structure. Write each premise as a box or a numbered line, and draw arrows to the conclusions they support. If two premises must work together, as the two above do, join them with a bracket and send one arrow from the pair. If two premises support a conclusion independently, send separate arrows.
This step often shows that an argument is more complicated than it seemed. Some passages contain two or three sub-arguments, each with its own intermediate conclusion. Mapping them separately keeps each manageable.
Step 4: Test the form and the premises
First test the form. Is the argument valid? The moral argument above has the form of modus tollens: if not A then not B; B; therefore A. This form is valid. So the argument is not open to attack on the ground of invalid form. If the form had been invalid, the next step would be pointless until the form was repaired.
Then test each premise by itself. Is it clearly true, doubtful or false? What reasons are given for it? Who accepts it and who does not? In the example, the second premise is accepted by many people who are not religious, though some philosophers deny that objective moral values exist. The first premise is accepted by many theists and disputed by many others, including some philosophers who hold that moral values can have a foundation without God. Mark the crucial premise, which is the first.
Step 5: Add objections and replies
For each doubtful premise, write the strongest objection a thoughtful critic would raise, and the best reply a defender would make. For the first premise, a critic may say that moral truths are necessary truths like those of mathematics, needing no divine foundation. A defender may reply that necessary truths still need explaining, or that moral duties seem to require a person who commands them. A critic may respond in turn. Write down how far this chain of replies goes.
Finish with an overall verdict phrased with care. For example: the argument is valid, the second premise is widely accepted, and the first premise is disputed and decides whether the argument persuades. This is a more useful verdict than good or bad.
- What are the six moves of the mapping procedure?
- Why is it important to define terms such as objective before evaluating a premise?
- What is the difference between linked and convergent premises?
- Why test the form of an argument before testing the premises?
- How would you decide which premise in an argument is crucial?
- What makes a verdict on an argument fair?
Examples
The map in numbered form
(1) If God does not exist, objective moral values do not exist. (2) Objective moral values exist. (3) Therefore, God exists. Premises 1 and 2 are linked, since each is needed. The form is modus tollens, so the argument is valid. The dispute concerns premise 1 and, for some, premise 2.
A convergent case
A writer argues that a letter was written by a particular person because the handwriting matches, because the vocabulary matches and because the letter mentions events only that person knew. The three premises support the conclusion independently. If the handwriting evidence is challenged, the other two remain. A map would show three separate arrows.
A student’s improvement
A student first writes in a sentence that the moral argument fails because morality is just opinion. After mapping, the student sees that this attacks premise 2, not premise 1, and that many critics of the argument actually accept premise 2. The map helps the student target the right claim. This is a constructed example.
Different perspectives
Catholic natural law tradition
Catholic thinkers in the tradition of Aquinas hold that moral law is grounded in the nature that God gave to human beings, and some use arguments from moral experience to point to God. They would affirm that objective morality needs a foundation, though they distinguish what can be known by reason from what is revealed.
Evangelical moral apologists
Writers such as C. S. Lewis and William Lane Craig defend versions of the moral argument. They hold that objective moral values and duties are best explained by God’s nature or commands.
Non-theistic moral realists
Some philosophers hold that objective moral truths exist without God, grounded in the nature of persons or in necessary truths. They deny the first premise while accepting the second.
Moral anti-realists
Other philosophers deny that objective moral values exist, holding that morality arises from human feelings, agreements or evolution. They reject the second premise and often add that Christians are mistaken to take moral experience as a sign of God.
Jewish and other traditions
Jewish thinkers, such as those in the tradition of the Talmud, treat moral law as given by God, though they do not usually present it as an argument for God’s existence. They point to long-standing disputes within their own tradition about how law and reason relate.
Why it matters
Mapping makes disagreement productive. Instead of one party saying the argument is nonsense and the other saying it is obvious, both can point to a numbered premise. It also protects the student from being swept along by an argument that sounds good but hides a weak point, or from dismissing one that has a strong core. And it gives a tool for writing the extended assignment at the end of this course.
Common misunderstandings
Misunderstanding: Mapping an argument means attacking it.
Correction: Mapping comes first and is neutral. The aim is to see the argument clearly. Evaluation follows, and may find the argument strong.
Misunderstanding: If an argument is valid, there is nothing more to check.
Correction: A valid argument still needs true premises to be sound. Mapping directs attention to the premises that carry the weight.
Misunderstanding: A good map always shows a complicated argument.
Correction: Many good arguments are simple. A short map with two premises can be accurate and useful.
Misunderstanding: Only the author can say what the argument is.
Correction: A reader can reconstruct an argument from the text, and should do so charitably. If the author later says the reconstruction is unfair, the map can be revised.
Knowledge check
List the six moves of mapping an argument.
Find the conclusion, list the premises, add unstated premises and clarify terms, show how the premises connect, test the form and each premise, and consider objections and replies. After these a careful verdict can be given.
What is the difference between linked and convergent premises?
Linked premises work together, so that removing one removes the support, as with the two premises of a modus tollens argument. Convergent premises each support the conclusion independently, so that the conclusion keeps some support even if one premise falls.
Why test the form before the premises?
If the form is invalid, the argument fails even if every premise is true, and time spent debating the premises is wasted until the argument is repaired. If the form is valid, attention can go to whether the premises are true.
What is a crucial premise?
It is a premise on which the argument most depends and which is most open to dispute. In the moral argument used here it is the premise that without God there are no objective moral values. Identifying it shows where the debate is centered.
What should an overall verdict on an argument include?
It should say whether the form is valid, which premises are widely accepted, which are disputed and why, and how strong the best objections are. A careful verdict avoids the labels good and bad and says what the argument achieves and where it is open to challenge.
Think it through
- Choose an argument you reject. Can you state it so that its defender would say you have it right?
- What happens to your view of an argument when you see that the dispute is about only one premise?
- How many premises can you hold in mind at once without writing them down?
- Does mapping an argument make you more or less confident in your own conclusions?
Independent assignment
Map an argument from your reading
In your own notebook, write 600 to 800 words. Choose one of Aquinas’s Five Ways or a short passage from Mere Christianity (see the library). Carry out all six moves of the procedure. Present the numbered argument, a simple sketch of the connections, an evaluation of each premise, one objection with a reply, and a brief overall verdict. Keep this for yourself.
Further study
- Thomas Aquinas, Summa Theologiae I, Q. 2: The Existence of God Choose one way to map completely.
- C. S. Lewis, Mere Christianity Map the argument in the opening chapters of Book 1.
- Stanford Encyclopedia of Philosophy, Moral Arguments for the Existence of God Read for the range of moral arguments and the objections they meet.
- Stanford Encyclopedia of Philosophy, Cosmological Argument A second argument for mapping practice.
- Stanford Encyclopedia of Philosophy, Fallacies Check your maps for informal fallacies.