A Field Guide to Critical Thinking

The six rules of evidential reasoning are my own distillation and simplification of the scientific method. To make it easier for students to remember these half-dozen guidelines, I've coined an acronym for them: Ignoring the vowels, the letters in the word "FiLCHeRS" stand for the rules of Falsifiability, Logic, Comprehensiveness, Honesty, Replicability, and Sufficiency. Apply these six rules to the evidence offered for any claim, I tell my students, and no one will ever be able to sneak up on you and steal your belief. You'll be filch-proof.

Falsifiability

It must be possible to conceive of evidence that would prove the claim false.

Logic

Any argument offered as evidence in support of any claim must be sound.

Comprehensiveness

The evidence offered in support of any claim must be exhaustive -- that is all of the available evidence must be considered.

Honesty

The evidence offered in support of any claim must be evaluated without self-deception.

Replicability

If the evidence for any claim is based upon an experimental result, or if the evidence offered in support of any claim could logically be explained as coincidental, then it is necessary for the evidence to be repeated in subsequent experiments or trials.

Sufficiency

The evidence offered in support of any claim must be adequate to establish the truth of that claim, with these stipulations:

the burden of proof for any claim rests on the claimant,
extraordinary claims demand extraordinary evidence, and
evidence based upon authority and/or testimony is always inadequate for any paranormal claim

James Lett