How to draw an argument map

An argument in an essay or a book comes as paragraphs. An argument map lays the same argument out as a diagram, with the claim in one box and the reasons for it in others.

What an argument is

The Stanford Encyclopedia of Philosophy defines an argument as a structure in which some parts, the premises, offer support to another part, the conclusion. A marker such as "hence" or "therefore" shows that the conclusion follows, and that marker can be stated or left implicit.

What a map looks like

Wikipedia's article on argument maps describes the most common kind as a tree, with each reason leading to the conclusion. Some people put the conclusion at the top and some at the bottom. There is no agreed rule.

The article adds that in maps drawn with software, each box usually holds a statement. Each line or arrow stands for an inference, the move from a reason to what it supports. A map can show objections as well, set against the claim they weaken.

Mapping a passage, step by step

The same article sets out a method recommended by the philosophy professor Maralee Harrell:

1. Find every claim the author makes.
2. Rewrite each one as a statement on its own, without the words it does not need.
3. Decide which statements are premises, which are sub-conclusions and which is the main conclusion.
4. Add any conclusions or premises the author implies but never states. Whether this step is needed depends on what the map is for.
5. Put the statements into boxes, and draw a line between any boxes that are linked.
6. Use arrows to show support running from premises to a conclusion.

Parts you will meet

Wikipedia's article calls a premise dependent, or a co-premise, when it gives support only once it is joined to another premise. An independent premise can support the conclusion on its own.

The same article calls a claim an intermediate conclusion, or sub-conclusion, when one claim supports it and it then supports a further one. A chain of these is sometimes called a serial argument.

Arguments in A-level and university work

AQA's A-level Philosophy specification says students will analyse and evaluate the arguments of others, and construct and defend their own.

The University of Leeds library describes critical thinking at university as questioning the information, ideas and arguments you meet, rather than taking them at face value. It says students need to develop well-reasoned arguments of their own for their assignments.

Tools that draw maps

Listed in alphabetical order.

• Argdown uses a simple text syntax, and turns what you write into an argument map while you type. Maps can be exported as images or PDFs.
• Kialo Edu lets students write pros and cons under each other's points, which builds an interactive discussion map.
• Rationale creates argument maps online. Its makers publish a set of critical questions for judging a map, inspired by the work of the philosopher Douglas Walton.

Useful links

• Argument and Argumentation (Stanford Encyclopedia of Philosophy)
• A-level Philosophy 7172: specification (AQA)
• What is critical thinking? (University of Leeds Library)
• Argument map (Wikipedia)
• Argdown
• Kialo Edu
• Rationale