Cognitive Biases, Reasoning, and Truth
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Sign In!
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Review
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Cognitive Bias v. Fallacy
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Types of Biases
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Truth and Knowledge
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For next time:Comprehensive Chapter 1 exercises due:
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(1-3): 1, 4, 6; (1-5): 2, 5, 8; (1-6): 3, 4, 8; (1-7): 4, 5, 7; (1-9):
all of it
Review
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Claims have propositional structure. They are declarative.
Sentences that are claims can be true or false
Imperative sentences are not claims. Imperative sentences state
commands.
Interrogative sentences ask questions. Questions are not claims
but questions raise issues
There are many different kinds of claims: objective, subjective,
factual, evaluative, and policy
Factual, evaluative, and policy claims can be either objective or
subjective
Review
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Arguments can only be composed of claims
Arguments have two essential parts: premises and
conclusion
Claims that are premises function as evidence/support that
is meant to make the concluding claim more likely to be
true
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Premises must therefore be relevant to the conclusion
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True premises are cogent premises
Fake Quiz
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Which of the following is a subjective policy claim?:
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Rocky road is the best ice cream flavor
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We must allow the Bush-era tax cuts to expire
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If some neutrinos can travel faster than light then
we can probably build a time machine in the distant
future
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Should we reform our health care policy to give
everyone universal access?
Fake Quiz
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Which of the following is an argument? Why?
(a) If there is smoke then there is fire. There is
smoke. Therefore there is fire
(b) The price of gold has been going up over the last
10 years. It has risen about 600% during that time
period.
(c) I am better at playing checkers than I am at chess
but I am not very good at either game to be honest.
Cognitive Bias v. Fallacies
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A cognitive bias is sometimes confused with another form of
mistaken reasoning known as a fallacy
Cognitive biases affect belief formation in non-rational ways
and are almost always non-conscious (we are not aware that
we are subject to the biases)
A fallacy is a mistake in reasoning which can be explained by
cognitive biases
Personal attacks are a kind of fallacy (ad hominem) that we
might resort to if we run out of good reasons or if we are
subject to one of several cognitive biases
Common Cognitive Biases
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Belief Bias:
We are far more likely to agree that an argument is
good when we already agree with the conclusion
This is a bias because we are being persuaded that
an argument is good by something other than the
relevance and truth of an argument's premises.
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1. All Dogs are animals
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2. Some animals are German Shepherds
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3.Therefore some dogs are German Shepherds
Belief Bias
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1. All Dogs are animals
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2. Some animals are German Shepherds
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3.Therefore some dogs are German Shepherds
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This is a bad argument. Why? The fact that some animals are
German Shepherds is not relevant evidence for believing that some
dogs are German Shepherds.
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All As are Bs
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Some Bs are Cs
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Can we conclude that ANY As are Bs?
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Some animals reproduce asexually....
Availability Heuristic
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Many cognitive biases have to do with how we
judge the frequency or likelihood of things.
For example:
Quick! Are there more words (in English) that begin
with the letters r or k or are there more words where
r or k are the 3rd letter in a word?
What do you think?
Availability Heuristic
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There are 3 times as many words (in English) that have
r or k as the 3rd letter than there are that begin with r or
k
Is this surprising?
The availabiliy heuristic tells us that we judge the
probabilities of an event by how easy it is for us to
recall instances of that event
In this case it is easy for us to remember words that
begin with r or k so we judge that there are probably
more of them.
Availability Heuristic
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The availability heuristic affects how we perceive many
different aspects of our day to day lives
The media tend to focus their reports on extraordinary,
rare, and negative events (violent crimes, thefts,
corruption, etc)
Because these events are easy to remember we tend to
think our cities are far more dangerous or corrupt than
they actually are
Multiple exposures to the same commercials also trigger
the availability heuristic
Framing Effects
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Our judgments about how likely or desirable something is
depend strongly on how information is presented to us
For example: Consider the different frames (and their effects on
perceived attractiveness) of the following:
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1. Wealthiest 5% of the population
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2. Job Creators
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3. The rich
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These three terms all describe the same population but people
prefer taxing 'the rich' more than the 'wealthiest 5%' and they do
not at all prefer taxing 'job creators'
Anchoring and Framing Effects
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Framing effects can also be used to trigger a
cognitive bias called anchoring
Anchoring occurs when we focus on one (mostly
irrelevant) factor to judge the relative probability or
value of something
Ex- What percentage, above or below 10%, of
African nations are members of the United Nations?
Take a guess
Anchoring
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What percentage, above or below 10%, of African nations are
members of the United Nations?
When phrased this way the average answer is about 25%
However, the average guess is 45% when phrased as “What
percentage, above or below 60%, of African nations are
members of the United Nations?”
The question doesn't change the information we already know
(even though it might be very little) but the frame changes the
numbers we anchor on and thus dramatically changes our
judgments of likelihood
The Bandwagon Effect
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Later in the quarter we will study a fallacy called the
Bandwagon fallacy. The bandwagon fallacy is so convincing
because of the cognitive bias (confusingly) called the
Bandwagon Effect
The bandwagon effect relates to our preferences
We tend to align our preferences with the preferences of the
majority
We shift our preferences from one product (MySpace) to
another (Facebook) more rapidly depending whether we
think that others are doing the same
The Bandwagon Effect
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The bandwagon effect plays a very large role in political
elections
Voters tend to shift their votes to the perceived front-runner in
an election
What matters here is that a candidate is perceived as a frontrunner
Political polls showing that one or another candidate will win
an election, for example, tend to dramatically sway undecided
voters toward the perceived leader
This is why the framing and bandwagon effects are often used
in political campaigns
Negativity Bias
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The bandwagon effect tells us that we have an implicit bias to
make our preferences match the preferences of perceived
majority groups
This bias is magnified if the preferences of the perceived
majority are negative
If we are presented with equally strong positive and negative
information about something (a person, a policy, a film, etc)
we overwhelmingly form a negative opinion of it
We subjectively weigh the negative information as far more
important than the positive even if both are equally relevant
Negativity Bias: Examples
-Negativity bias (i.e. subjectively valuing negative information
more than positive) manifests in several ways
-Loss Aversion: we weigh losses as more significant, more
harmful, than gains of the same size
-ex: receiving $5 is rated as far less significant than losing $5
-Judgments of character: we weigh negative information about a
person as revealing their true nature
-ex: If David was honest with us in three of our last four meetings
and dishonest with us once we will tend to rate David as a
dishonest person.
Negativity Bias
-Did you ever wonder why Political Campaign
Advertisements are predominantly negative?
-Campaign managers know about the negativity bias, the
availability heuristic, and the bandwagon effect.
-Negative Campaign Advertisements are designed to work
around critical thinking by triggering these cognitive
biases.
-Let's take a look at, and discuss, an example...
Self Assessment Biases
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We are especially bad at making assessments of our own
abilities
Overconfidence Effect: the harder and less familiar a task
the higher our estimates are of how well we performed it
Better-than-Average: if asked to rate our performance
relative to others on a task we are (almost all) likely to say
we performed better than average even though this is
impossible
-ex- Do you believe you are in the top 30% or lower 70% of
students in your year (freshman, sophomore, etc)?
Self Assessment Biases
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The Bias Blind Spot: we also have a bias about our
perception of how likely we are to fall prey to our biases
Studies have shown that people who have the
overconfidence and better-than-average effects
explained to them will judge that they are not nearly as
likely as others to succumb to these effects
This cognitive bias is known as the bias blind spot
Do you think that your judgments are often biased in
these ways?
For next time
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Comprehensive Chapter 1 exercises due
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Bring this to class
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Late homework will not be accepted without
good reason