# Chapter 12: Deductive Reasoning and Decision Making

## 47 terms

### Thinking

requires you to go beyond the information you were given; thinking also has a goal such as a solution, a decision, or a belief.

### Deductive Reasoning

You are given some specific premises and you are asked whether those premises allow you to draw a particular conclusion, based on the principles of logic.
- provides you with all the information you need to draw a particular conclusion
- the premises are either true or false, and formal logic specifies the rules you must use in order to draw conclusions. All men are mortal
Socrates is a man
Therefore, Socrates is mortal

### Decision Making

refers to assessing and choosing among several alternatives.
- more ambiguous
- some info may be missing or contradictory
- no clear-cut rules tell us how to proceed from the info to the conclusions
- the consequences of that decision won't be immediately apparent and you may need to take additional factors into account.

### Conditional (Propositional) Reasoning:

problems tell us about the relationship between conditions.
- the relationship between enrolling in a class and the completion of a prerequisite.
- "If...then..." structure; Valid? Not valid?

### Syllogism

consists of two statements that we must assume to be true, plus a conclusion. Major premise: All mammals are warm-blooded.
Minor premise: All black dogs are mammals.
Conclusion: Therefore, all black dogs are warm-blooded
- refer to quantities; all, none, some
- judge whither the conclusion is valid, invalid, or indeterminate

### The propositional calculus

a system for categorizing the kinds of reasoning used in analyzing propositions or statements

### Antecedent

refers to the first proposition or statement; the antecedent is contained in the "if.." part of the sentence.

### Consequent

refers to the proposition that comes second; it is in the consequence. The consequent is contained in the "then..." part of the sentence

### Affirming the antecedent

"if..." part of the sentence is true. Leads to a valid, or correct, conclusion.
i.e. "This is an apple; therefore it's a fruit."

### Affirming the consequent:

you say the "then..." part of the sentence is true. This leads to an invalid conclusion.
i.e. "This is a fruit; therefore this is an apple."

### Denying the antecedent:

you say the "if..." part of the sentence is false. Denying the antecedent also leads to an invalid conclusion.
i.e. "This is not an apple; therefore this is not a fruit."

### Denying the consequent:

you say "then..." part of the sentence is false. Leads to a correct conclusion
i.e. "This is not a fruit, therefore this is not an apple."

### Heuristic-analytic theory:

people may initially use a heuristic that is quick and generally correct

### Belief-bias effect:

occurs in reasoning when people make judgments based on prior beliefs and general knowledge, rather than on the rules of logic.
- example of top down processing

### The Standard Wason Selection Task: confirmation bias:

they would rather try to confirm a hypothesis than try to disprove it
-people who take time to carefully inspect the problem are more likely than impulsive people to select the two correct cards in this task.

### Heuristics:

general strategies that typically produce a correct solution.

### Representative:

If it is similar in important characteristic to the population from which it was selected.

### Representative heuristic:

we judge that a sample is likely if it is similar to the population from which this sample was selected.

### small sample fallacy

assuming that small samples will be representative of the population from which they are selected.

### base rate

how often the item occurs in the population

### base rate fallacy

underemphasizing important information about base rate

### Bayes' theorem

states that judgments should be influenced by two factors: the base rate and the likelihood rate.

### Likelihood rate

assesses whether the description is more likely to apply to Population A or Population B.

### conjunction rule

the probability of the conjunction of two events cannot be larger than the probability of either of its constituent events.

### Conjunction fallacy

they judge the probability of the conjunction of two events to be greater than the probability of a constituent event.
-spilling hot coffee seems more probable than spilling coffee...until you identify the conjunction fallacy.

### Availability heuristic

when you estimate frequency or probability in terms of how easy it is to think of relevant examples of something.

### recognition heuristic

typically operates when you must compare the relative frequency of two categories; if you recognize one category you conclude that the recognized category has a higher frequency.

### illusory correlation

occurs when people believe that two variables are statistically related, even though there is no real evidence for this relationship.

### Social cognition approach

we form stereotypes by means of our normal cognitive processes; motivational factors are less relevant.

### Anchoring and adjustment heuristic aka anchoring effect

we begin with a first approximation, an anchor, and then we make adjustments to that number on the basis of additional info.
i.e. the snow storm where they thought it would take an hour longer than normal to get home but really the cars blocking the street made it a 3 hour ride home.

### the belief- bias effect

we rely too heavily on our established beliefs

### the confirmation bias

we prefer to confirm a current hypothesis, rather than to reject it

### confidence intervals

ranges within which we expect a number to fall a certain percentage of the time.
- the confidence intervals that we estimate are definitely too narrow

### Framing effects

demonstrates that the outcome of a decision can be influenced by two factors
1. the background context of the choice
2. the way in which a question is worded (framed)

### prospect theory

refers to people's tendencies to think about possible gains as being different from possible losses.
Specifically:
1. When dealing with possible gains (i.e. lives saved), people tend to avoid risks.
2. When dealing with possible losses (i.e. lives lost), people tend to seek risks.

### Overconfidence

means that people's confidence judgments are higher than they should be, based on the actual performance on the task.

### Crystal ball technique

asks decision makers to imagine that a completely accurate crystal ball has determined that their favored hypothesis is actually incorrect. The decision makers must therefore search for alternative explanations for the outcome

### Planning Fallacy

people typically underestimate the amount of time (or money) required to complete a project; they also estimate that the task will be relatively easy to complete.

### Groupthink

can occur when a cohesive group is so concerned about reaching a unianomous decision that members ignore potential problems, and they are overconfident that their decision will have a favorable outcome.

### My-side bias

describes the overconfidence that one's own view is correct in a confrontational situation.

### Hindsight

refers to our judgements about events that already happened in the past

### Hindsight Bias

occurs when an event has happened and we say that the event had been inevitable; we had actually "known it all along."

### Maximizers

are people who have a maximizing decision making style; they tend to examine as many options as possible

### Saticifiers

are people who have a satisficing decision making style; they tend to settle for something that is satisfactory.

### Ecological rationality

describe how people create a wide variety of heuristics to help them make useful, adaptive decisions in the real world.

### Default heuristic

if there is a default option, people will chose it.
i.e. you have to sign up to be an organ donor here, while in France you automatically are one unless you sign otherwise