Reasons for Belief and Doubt – Chapter 4
When Claims Conflict
When two claims conflict, they simply cannot be true; at least one of them has to be false.
Principle; If a claim conflicts with other claims we have good reason to accept, we have good reasons for
When conflicting claims, you are not justified in believing either one of them until you resolve
• In what follows, “conflicts” means “contradicts or is contrary to”, in the technical sense just
• When a claim p (a statement, an assertion) conflicts with another claim q that we have
good reason to accept, we have good grounds for doubting p.
• When a claim p conflicts with another claim q, and we have no reason for believing one
over the other, we should suspend judgment concerning p and q.
• When a claim p conflicts with our background information, we have good reason for
• Background information – sometimes this means common knowledge shared by your peers,
sometimes it means your own personal background information. Neither category is exactly
fixed or determinate.
Principle; If a claim conflicts with our background information, we have good reason to doubt it
Sometimes, if the claim is dubious enough, we may be justified in dismissing a claim out of hand.
What should we believe about a claim that is not quite dubious enough to discard immediately
and yet not worthy of complete acceptance?
We should proportion our belief to the evidence
The more evidence a claim has in its favor, the stronger our belief in it should be Twinkle Kavi
Experts and Evidence
An expert is someone who is more knowledgeable in a particular subject area or field than most
other people are.
They are more likely to be right because;
(1) They have access to more information on the subject than we do
(2) They are better at judging that information than we are
Someone who knows the lore of a field but can’t evaluate the reliability of a claim is no expert
This suggests some more principles:
If a claim conflicts with expert opinion, we have good reason to doubt it.
When the experts disagree about a claim, we have good reason to suspend judgment concerning it.
Two Cautions Concerning Experts
• Experts may be biased, dishonest, or otherwise dysfunctional, or just plain wrong. So we
shouldn’t always believe experts.
• Experts need not settle every question.
Fallacious appeal to authority
• As we’ve seen, it can be perfectly legitimate to trust experts. But, the fallacy of appeal to
authority occurs in these cases:
(1) Taking an expert as authoritative outside his/her field.
(2) Taking a non-expert to be an expert.
Personal experience broadly defined, arises from our senses, our memory, and our judgment
involved in those faculties
We accept a great many claims because they are based on personal experience - our own or
But can you trust personal experience to reveal the truth?
It is reasonable to accept the evidence provided by personal experience only if there’s no good reason to
If we have no good reason to doubt what our personal experience reveals to us, then we’re
justified in believing it Twinkle Kavi
If we seem to see a cat on the mat under good viewing conditions, then we’re justified in
believing that there’s a cat on the mat.
• If our perceptual powers are someho