1.
Knowledge: Belief, Truth, and
Justification
Ideas and Debates

2.
Critical Thinking: Why Does it Matter?
• Why is critical thinking important?
• Important and valuable for two main reasons
• Increases our chances of gaining knowledge
• Essential to being autonomous
• We don’t just want to have an opinion about the facts; we want to
know the facts
• Critical Thinking is directed at knowledge

3.
Knowledge and Truth
• Traditional definition of knowledge: justified true belief
• What is truth?
• Three attitudes one might take to a subject matter
• Realism
• Relativism
• Nihilism

4.
Knowledge and Truth…
• The scene is a campus security office, where two students are being
questioned. A few minutes earlier, they were engaged in a fistfight in
the cafeteria. The campus police ask them again and again how the
fight started. The stories conflict. Because each student seems
genuinely convinced that the other one was the aggressor and there
were no witnesses, the campus police have no hope of discovering
the truth. But is there a truth to discover? Or are there two truths,
one for each student’s story?

5.
Knowledge and Truth…
• How many marbles are there in a jar?
• For a Realist
• (1) There are truths about a subject matter and (2) what those truths are is
independent of what anybody thinks they are.
• For a Relativist
• (1) There are truths about an area but (2) what they are depends (in some
way or other) on what we (or someone) take those truths to be.
• What do a realist and relativist disagree about?

6.
Knowledge and Truth…
• For a Nihilist
• There is no single, right answer to the question how many marbles it contains. Every
opinion is just as good as any other opinion. There is no right answer! There are no
truths at all about a subject matter.
• One could be a realist about one subject matter and a relativist about
another and a nihilist about a third
• For years grade school students faced this question on their science tests:
“True or False—The famous rings of the planet Saturn are composed of
solid material.” If the students marked “true,” they lost credit, because the
“truth” was that Saturn’s rings were composed of gas or dust. Then, in
1973, radar probes revealed that all those wrong answers had been right.
Saturn’s rings are, in fact, composed of solid matter. This confusing case
seems to suggest that the truth changed. Did it really?

7.
Knowledge and Belief
• Knowledge is justified true belief
• What do we mean by belief?
• Believing something to be true is taking a certain attitude toward it:
An attitude of acceptance
• Belief is not the only form of acceptance
• Presupposing something is also a kind of acceptance
• The importance of freedom of belief though not without
responsibility

8.
Knowledge and Justification
• Knowledge is justified true belief
• A belief is justified if it is based on or grounded in good reasons
• There are different kinds of reasons to believe something
• Three questions to ask
• (1) What kinds of reasons does Ahmed have for having this belief? (2) What
kind of reasons is critical thinking concerned with? (3) Why do those reasons
count as good reasons?

9.
Knowledge and Justification…
• “producing” reasons and “sustaining” reasons for a belief can be different
• There are emotional and pragmatic reasons
• Emotional reasons that involve the individual him/herself
• Emotional reasons that involve one’s community, culture
• There are epistemic reasons
• Critical thinking is concerned with these reasons
• A belief that is based only on emotional or pragmatic reasons cannot count
as knowledge

10.
Sufficient and Acceptable Reasons
• A belief is justified enough for knowledge only if it is based on good
reasons.
• Reasons have to be sufficient to support the belief
• Reasons have to be acceptable to support the belief

11.
Emotions and Evidence
• Emotions may not allow us to collect the evidence we need to justify
our beliefs
• Emotions may not allow us to investigating further
• When we identify too much with our own opinions and beliefs,
emotions can also become a hindrance
• Training oneself to distance from one’s beliefs so as to think critically
about them important though not easy

12.
Evidence
• Important kinds of evidence
• Personal experience
• Unpublished report
• Published report
• Eyewitness testimony
• Expert opinion
• Experiment
• Statistics
• Survey
• Formal Observation
• Research review

13.
Beliefs or Opinions about Matters of Taste
• Are all opinions the same? Can they be challenged?
• Personal preferences vs considered judgment
• Fundamental principle: Ideas are seldom of equal quality
• How about experts? Can’t they be wrong?