Read a Philosophical Argument, One Claim at a Time

Separate the parts of an argument

Take a deliberately simple example: all books on this shelf are novels; this book is on this shelf; therefore, this book is a novel. The first two statements are premises. The last is the conclusion. Together they form an argument whose structure you can inspect without knowing anything about the actual books.

In the interactive example, change the second premise. Notice how a small change can make the conclusion stop following, even though the sentences still sound plausible together.

Keep the form and the facts separate

Suppose a cookbook is sitting on the shelf. The statement that every book there is a novel would be false. That does not change the form of the first argument. It changes whether you have good premises to use in that particular situation.

The open logic textbook forall x: Calgary covers consequence, validity and formal methods for investigating arguments. Our shelf example is an original illustration of a small distinction, not a substitute for that wider subject.

Look for a possible counterexample

Now try this: all books on the shelf are novels; this book is a novel; therefore, this book is on the shelf. A novel on a desk is enough to show the problem. Both premises could be true while the conclusion is false. The second premise does not locate the book.

A useful objection identifies the exact step that needs support. “I disagree” tells you less than “this conclusion needs a further premise.” On a more difficult page, there may be an unstated assumption, an ambiguous term or a claim that needs evidence. Mark the uncertainty before attempting a verdict.

Choose a question for the next reading

Logic asks about reasoning and consequence. Epistemology asks about knowledge and justification. Ethics asks how to reason about what we should do. Philosophy of mind, aesthetics and philosophy of religion bring other questions into view. You can start with a question that matters to you and return to historical context as it becomes useful.

The six selections in our philosophy shelf are introductions to different branches. They are not a sequence that every reader must follow, and their authors need not agree.

Make a small reading note

• Write the conclusion in your own words, without strengthening it.
• List the reasons the author actually gives.
• Record one question about a premise or an inference.
• Return to the paragraph to check that your note is fair.

The aim of the first pass is to understand the argument well enough to discuss it. You can leave with a better question rather than a final answer.