Prologue

The most serious questions in life are usually about decisions that will have long-lasting consequences.

Depending on our outlook, they may appear as existential questions or as decisions in which a great deal is at stake.

Should I take this job?

Should I move?

Should I stay?

Should I invest?

Should I marry?

Should I break up?

Should I make amends?

Faced with such questions, we naturally begin looking for guidance.

We compare alternatives.

We gather information.

We ask others for advice.

We look for signs, evidence, rules, methods, principles, and procedures.

What we look for are criteria.

Good criteria, that is the hope, help us arrive at convictions worth trusting.

Sometimes because we must justify them before others.

Sometimes because we seek convictions that will remain convincing later.

The search for and use of criteria appears in countless forms.

A buyer compares reliability statistics before purchasing a car.

A patient evaluates treatment options.

A scientist chooses between competing hypotheses.

A voter attempts to understand political claims.

A mathematician evaluates a proof.

A critic appraises a new book.

Different domains employ different tools, but a common pattern remains visible.

The more important a decision appears, the stronger the desire for criteria tends to become.

This attraction is not hard to understand.

Good choices should not be a matter of luck.

We want to understand if there are procedures that lead to good convictions, what they are, and how they work.

At first glance the idea seems straightforward.

Find good criteria.

Use them to arrive at good convictions.