P&C 4.2 - Deductive and Inductive Reasoning

What is the Watson selection task?

• four cards on a table being R, G, 2, 7
• each card has a letter on one side and number on other
• need to decide if rule is correct of if R one one side then 2 on the other
• only turn over cards needed
• 5-10% choose correctly
• may be using simple strategies or don't understand rules

What is inductive reasoning?

• drawing general conclusions from particular examples
• probably but not necessarily true
• eg all swans I've seen are white so all swans are white

What is deductive reasoning?

• drawing definite conclusions if principles are true
• based on formal logic

What is informal reasoning?

• everyday reasoning
• based on relevant knowledge and experience
• eg ghosts exists bc no ones proved they dont

How is hypothesis testing used in inductive reasoning?

• scientists use based on limited data

• falsification of null hypothesis

• Either confirmation or falsification

What are the limitations of hypothesis testing?

• confirmation can never fully support hypothesis
• falsification can never prove hypothesis wrong

What is the main task associated with inductive reasoning?

Wason's 2-4-6 task

What is Wason's 2-4-6 task?

• given those 3 numbers and guess rule that generated these numbers
• give 3 further numbers to test hypothesis
• 21% guess correctly on first attempt but 28% never do
• actual rule is ascending in order of magnitude

How does Wason's 2-4-6 task use confirmation bias?

• guess that it goes up in twos
• generate sequences conforming to this rule
• fail to falsify hypothesis

What are the limitations with Wason's 2-4-6 task?

• provides insight into indicative reasoning and how scientists reason however:

• not real world as we dont often get detailed immediate feedback

• rule is so general so confirmation testing isnt appropriate

• confirmation bias isn't always present

• not real world as we dont often get detailed immediate feedback

• rule is so general so confirmation testing isnt appropriate

• confirmation bias isn't always present

How are scientists known to hypothesis test?

• unusualness heuristic where they re guided by unusual results
• "what if" hypothesis generated without experimentation

What research is there supporting hypothesis testing in scientists?

• molecular biologists has 417 results, 223 inconsistent with predictions

• 88% blamed on methods

• 12% modified theories based on discrepant results

• however 61% change theory when discrepant findings are replicated

What is conditional reasoning within deductive reasoning?

• symbols stand for sentences eg P for study and Q for good grade
• logical operators applied to reach conclusions
• eg if you study, you get a good grade OR if P then Q

What are different elements within conditional reasoning?

• antecedents and consequents
• binary
• modus ponens
• modus tollens

What are antecedents and consequents?

• antecedent is premises

• consequent is conclusion

What is binary?

• affirm or refute consequent based on antecedent

What is modus ponens?

• affirming the antecedent

• if A then B, A therefore B

• When it rains, ground is wet, it is raining therefore ground is wet

What is modus tollens?

• denying the consequent

• If A, then B. Not B. Therefore, not A

• If it rains, then ground is wet. Ground is not wet therefore it is not raining.

What are strengths of conditional reasoning?

• appropriate irl as if you study you do get a good grade
• unlikely is probabilistic whereas logic is binary

What are limitations of conditional reasoning?

• logic can construct false conclusions
• if Sarah is in Rio, then she isnt in Brazil
• Sarah is in Rio therefore not in Brazil
• false but logically inconsistent
• real world knowledge is irrelevant in conditional reasoning

How do counter examples support conditional reasoning?

• varied number of counter examples
• if the brake is depressed then car flows down
• counters such as alternatives (running out of petrol) and disables (broken brake)
• disablers supports modus ponens as decreases acceptance of valid conclusions
• alternatives increase correct rejection of invalid conclusions

What study highlights incompetence in conditional reasoning?

• if a rock is thrown at a window, a window will break. A window is broken therefore a rock was thrown
• if a finger is cut, it will bleed. A finger is bleeding, therefore it was cut
• both inlaid and affirms the consequent
• people more likely to accept 2 than 1

Why are we not good at conditioning reasoning?

• choose due to probaility of relationship in real world (close 1-1 correspondence)
• generate counter examples and if successful then we reject conclusion
• aren't good and often use real world knowledge inappropriately

What are deductive and informal reasoning based on?

• two examples of drug is safe bc we found no evidence it isnt and ghosts exist bc no one has proved they dont but ppl are more likely to pick 1 even though they're logically identical

• deductive reasoning is binary (true or false)

• informal reasoning is probabilistic (eg 80% chance of being correct)

What is the straw-man fallacy?

• focus on weaker points of opponents arguement to decrease probability of their view being correct
• your argument becomes relatively more probable

How does informal reasoning link to personal motivation?

• evaluate statements with respect to one's own beliefs (myside bias)
• college students who drink alc in college are more likely to become alcoholics in later life
• gap in salary between men and women decreases substantially when employed in same position
• students who drank alc rate accuracy of 1 lower than those who dont drink
• women rated accuracy of 2 lower than men

How does informal reasoning link to climate change?

• best predictor of denial of climate change was cultural values
• egalitarian communication" vs "hierarchical individualists"
• little to do with actual evidence
• those dismissive remembered very hot summer as colder than ones concerned about climate change

What influences informal reasoning?

• based on probabilities
• more akin to real world reasoning
• knowledge, experience, cultural values, motivation all contribute

What is bounded rationality?

• rational but within limits of cognitive capacity
• produce workable solutions to real world problems in spite of limited processing resources
• correlation between performance in reasoning tasks and IQ
• more processing capacity = better at reasoning