Important Practice Reasoning Questions “Work Book” (Syllogism With Explanation)-Www.ibpsguide
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ReasoningFabian A. Soto
March 21, 2016
What is reasoning?
What is reasoning?Up to this point, we have discussed mostly how we
process information coming from the outside world
Our cognitive processes are also able to go beyond the
information given through thinkingWe can produce new mental representations on the basis
of previous representations
In reasoning, the previously held representations are
premises and the new representation is a conclusionthat follows logically from the premises.
There are two basic forms of reasoning
Here we will focus on deductive reasoning
Deductive reasoning tasks
Deductive reasoning tasks1. Syllogisms
They present premises like “all X are Y”, or “no X are Y”
Then they ask about whether a conclusion is true
For example:All men are mortalSocrates is a manSo, Socrates is mortal
2. Conditional reasoning
They present premises like “If X, then Y”, “If X and Y, thenZ”Then they ask about whether a conclusion is trueFor example:I parked in the street. If it rains outside, then my car willget wetIt rained outsideSo, my car got wet
What follows the “if” is called the antecedent“If it rains outside”: this is enough for your car to get wetWhat follows the “then” is called the consequent“Then my car will get wet”: this must be true to concludethat it rained, but not enoughFor example, you would not conclude this if nothing elseis wet
Human irrationality
Human irrationality
Our performance in these tasks systematically deviates
from what is expected by formal logic
We seem to be irrational
This is easier to see under some circumstances:
1. We are bad with negatives
Our performance drops when the premises contain NOT
or NO
If it doesn’t not rain outside, my car will not not get wet
My car is not wet
?
2. We are bad with abstract problems
Our performance drops dramatically when we go from
familiar examples to abstract problems
For example:
If X, then A is B
A is B
?
3. Our reasoning is biased by what we know
Sometimes we make judgements based on prior beliefsor general knowledge, instead than based on thepremises and the rules of logicThis is called belief-bias
People with higher IQs and more flexible thinking (easierto be swayed by good arguments) perform better
4. We look for evidence that confirms our beliefs
Sometimes we draw the wrong conclusions not because
of a failure in logic, but because of a problem with our
premises
For example, this happens in hypothesis testingWe use logic to determine how to test a hypothesis: “If the
hypothesis is true, then I should observe X”
However, we are biased to try to confirm our hypotheses:
confirmation bias
One way to study hypothesis testing is with Wason’s rulediscovery taskThe participant is presented with a triple, for example: 2,
4, 6
They have to think of a hypothesis about the rule
underlying the triple, for example: “three even numbers in
ascending order”
They have to propose a new triple to test their rule, for
example: 8, 10, 12
The experimenter gives feedback about whether or not
the new triple conforms to the rule
Rinse and repeat
The previous example is typical of people’s behavior: theytest their rule using a triple that conforms to it:
Can You Solve This?
Another hypothesis testing task is the Wason selectiontask
The Wason Selection Task - Four Card Problem Interactive Video
Antecedent: “If a card shows an even number on oneface”Consequent: “then its opposite face is blue”"Most people decide to affirm the antecedent (valid): pickthe even numberMost people avoid to deny the consequent (valid): pickthe the green cardSome people decide to affirm the consequent (invalid):pick the blue card
The duality of human thought
The duality of human thoughtSo on one hand, we are bad at formal reasoning, but on
the other, we are able to realize how bad we are
How is this possible?
An explanation comes from dual process theory (Evans,
1989)
We make mistakes because we use heuristicsThese are “quick and dirty” rules, work generally but not
all the time
A form of Type 1 processing: fast, automatic, no
awareness required
We can correct our mistakes because we use analyticthinkingThis is appropriate deductive reasoningA form of Type 2 processing: slow, controlled, requiresawareness and attention
Some variables produce a shift from analytic to heuristicreasoning (Evans, 2008):Time pressureWorking memory loadAgeCognitive abilityThis confirms that analytic reasoning, but not heuristicreasoning, is slow and uses executive functions
SummaryDeductive reasoning is studied with syllogism andconditional reasoning tasksPeople make many errors in these tasks: bad withnegatives, bad with abstract problems, belief bias,confirmation bias.Problems in deductive reasoning can be explained by theuse of heuristicsWe can correct our mistakes because we also haveaccess to analytical thinking