study sheet - Deductive Reasoning 1 Definition Conclusions...

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Deductive Reasoning
1. Definition: Conclusions that follow with certainty from their
premises.
2. Rule of inferences in the logic of the conditional:
a. Modus ponens : Infer the consequent of the conditional
if we are given the antecedent. Given if A then B and
proposition A, we can infer B (Valid deduction).
b. Modus tollens : If we are given A implies B and that B
is false, then we can infer that A is false (Valid deduction).
3. Invalid deductions:
a. Affirmation of the consequent : Given B is true, infer
A is true.
b. Denial of the antecedent : Given A is false, infer B is
false.
**People are only able to show high levels of logical
reasoning modus ponens .
4. Wason Selection Task:
a. When presented with neutral material in the Wason
selection task, people have particular difficulty
in recognizing the importance of exploring if the
consequent is false.
b. When participants take the perspective of detecting
whether a social rule has been violated, they
make a large proportion of logically correct
choices in the Wason card selection task.
c. Oaksford and Chater explains that behavior in the
Wason card selection task can be explained if we
assume that participants select cards that
will be informative under a probabilistic model.
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Inductive Reasoning
1. Definition: The conclusion does not necessarily follow from the
premises.
2. Inductive reasoning is relevant to many aspects of everyday
life: doctor trying to diagnose the cause of a set of symptoms.
3. In choosing instances to test a hypothesis, people often focus

on instances consistent with their hypothesis, and this can
cause difficulties if their hypothesis is too narrow.
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Decision Making
1. Subjective Utility: The value that we place on $$ is not
linear with the face value of the money.
a. When it comes to a point when one has enough money
and that there really isn’t much difference for
them between 1 million dollars and 2.5 million
dollars.
b. Properties:
I. The graph is curvilinear such that it takes more
than doubling in the amt of money to
double its utility.
II. Steeper in the loss region than in the gain
region.
c. Subject probability: Not identical with the objective
probability. Very low probabilities are overweighed
relative to high probabilities .
2. Framing Effects: People’s decisions vary, depending on
where they perceive themselves to be in the utility curve.
a. Example: If a store offers $5 discount off of $15, the
person is likely to make an effort to go to the
other store, but not likely if it’s $5 off of $125 item.
3. When there is no clear basis for making a decision, people are
influenced by the way in which the problem is framed.
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Problem Solving
1. The nature of problem solving:
a. Example: Kohler’s chimps – 3 essential features that
qualify as problem solving.