"The Scientific Method as an Attitude"

• how do you evaluate evidence?
• how do you approach problems?

The Method of Authority is Wrong Because I said so...
 
 
 
 

Scientific Explanations Are:

• Empirical
• Testable
•  Creationism vs. Evolution
• Not really a versus (faith vs. empirical explanation)
• Religion begins where science stops (objective tests)
• Why am I here?
• Parsimonious and General
• Tentative (Aristotle > Newton > Einstein > ???)
• Rigorously Evaluated
• Replication
• Scope of the theory
• Competition with other theories
• Predictive
• Can an astrologer get a rover to Mars?
• pretty close
• Non-scientific explanations are often Post-hoc
• Dinosaur bones are made of rock;
• earth is 6000 years old (huh?)
• Rational

Commonsense (belief-based) Explanations
 
 

• Also based on observation
• Not systematic or controlled
• Not Experimental
• Superstitions
• Can prove illusory
• Boaz Keysar, "The goose hangs high."
•  Only make sense locally
• "The heart grows founder with distance."
• "Out of sight, out of mind."

Of course, science doesn't always get it
right?

• The ether
• Phrenology

As a matter of fact, science is always wrong, that's the point

• it's just more right than anything else

Circular Reasoning or Tautology

• Aggressive Behavior < >Aggressive Instinct
• Catch 22 - "You got flies in your eyes."

Rational Method (Descartes)

• The conclusion is true if it follows from the premises
• Deduction
•  Not actually how science works (exactly)

Deduction

Consider an argument:

All Horses are Mammals    <--- premise 1
All Mammals are Animals <--- premise 2
All Horses are Animals       <--- conclusion
 

A valid deductive argument:
If the premises are true, then the conclusion must be true.

Deductive reasoning is truth preserving, because if the premises are true, then the conclusion must be true.
 
 

Validity and Truth are separate concepts
 

All Horses are Mammals
All Mammals are Animals  <---Valid andTrue
All Horses are Animals
 

All Horses are Mammals
All Mammals are Trees  <---Valid, but not True
All Horses are Trees

Premise 2 is False, but the conclusion would be true if it were True
 
 
 
 
 

Reasoning is hard

Which Cards do you have to turn over?

If there is a vowel on one side of the card.
then there is an odd number on the other side:
 

(Turn over cards A and D)
 
 

(This example becomes easier if phrases in terms of a familar rule, like drinking)

If you have a beer, then you are over 21.
 
 
 
 
 
 

22

19

 
 
 
 
 
 
 
 

Valid and Invalid Arguments

Valid Arguments

Affirming the Antecedent

P->Q
       P
_______
      Q   (Modus Ponens)

Denying the Consequent

P -> Q
NOT Q
______
NOT P (Modus Tollens)
 

Invalid Arguments

Affirming the Consequent

P->Q
       Q
______
     P
 

Denying the Antecedent

P->Q
NOT P
_______
NOT Q
 
 
 
 
 
 
 
 
 
 
 
 

Observation

• The importance of observation
• How can a measure be objective?

The fallacy of empiricism

• A common belief
• "If I see it, then it is true"
• Therefore, scientists should just observe and record behavior
• Observation does not take place in a vacuum
• Kuhn (1962) Paradigms
• What you will accept as evidence depends on theory
• e.g., Mechanic and car color.
• Behaviorism:  Can only look at input and output
• Information processing:  Can look at intermediate steps
• Different People "look" at different things.
• Who is a better baseball player?
• Stats freak:  Look at batting average and r.b.i.
• Owner:  Salary and gate attendance
• These people are not speaking the same language

A Paradox

• In our studies, we make observations
• Observations are used to build theories
• What counts as an observation depends on theory
• A study of human communication
• We could videotape a conversation
• What should we code?
• How often people hesitate in speech?
• Use of space filling (er, um)?
• Sneezes?
• How often they gesture?
• What kind of gestures they make?
• What if your theory is wrong?
• You might miss key pieces of information

Observation

• Observation is an important part of science
• Poses a particular problem in Psychology
• Problem 1
• Awareness of the experimental situation
• Problem 2
• Act of measurement may affect the behavior measured
• Issues to consider
• Minimize interference--Reactivity; Demand characteristics
• Maximize precision--Precision and validity
• Maximize objectivity--Expectancy and reliability

Minimizing Interference

• Reactivity
• Influence of the observer on the situation
• People are affected by being observed
• Fear of being evaluated
•  Increased arousal at being evaluated
• Mere presence rather than some action taken by observer
• From the newspaper:
• In a recent survey, 90% of people said they give to the homeless.  A government official said, "That doesn't mean that 90% of people give to the homeless, it means that 90% of people were afraid to tell a stranger that they don't care about the homeless."

Demand Characteristics

• Most people in a study want to be cooperative
• People will try to figure out what you "want" them to do
• Then they will do it
• Demand characteristics
• Cues other than the ones central to the research that guide subjects to the "right" behavior
•  Results aren't interesting if you tell them what to do.
• Could be aspects of the instructions
• Could be aspects of the task
• Study of problem solving
• People might use tools just because they were given