What is Deductive reasoning?
‘top down’ approach, more narrow, concerned with hypothesis testing
What is Inductive reasoning?
‘bottom up’ approach, more open-ended, more exploratory
What is the The Vienna Circle?
Logical positivism (observation – induction – verification = demarcation of science)
Problems with Verificationism
- Induction problem
- What about unobservable facts?
- Our observations may be wrong!
- Our observations are not objective
Who was Karl Popper (1902-1994)?
- Austrian-born scholar
- Member of the Vienna Circle
- Professor at the London School of Economics
- Popper’s initial interest was psychology
What did Popper believe?
- Falsification instead of verification
- Science constantly questions its explanations
- Physics: Progress through finding weaknesses of theories
- Psychoanalysis: Progress through finding corroborating evidence
What is Falsification?
disproving a hypothesis or theory
What is Falsifiability?
criterion for demarcating science form nonscience
Hypothetico-Deductive Method
-Observation – interpretation – hypothesis (falsifiable) – test – (loops around again)
What is Scientific Progress?
Inductive & deductive reasoning
What did Popper believe about a hypothesis?
Hypothesis should be directed at a possible falsification
What are Degrees of falsification?
- The more falsifiable a theory, the higher its scientific status
- Example: wine sours because of organisms. Wine sours because of bacteria coming from the air
- The more specific a statement, the more prone to falsification, the higher the scientific status
What is Theory of General Relativity?
- Describes relationships between space time and mass
- Prediction: large masses bend space-time so it appears light is bent
What are the criteria for choosing theories?
- Scope
- Precision
- Parsimony
- Increasing falsifiability
- Fruitfulness
What is Science ?
process of trial and error
What is scope?
- A good theory makes wide-ranging claims about the world
- Example: Mars moves in an ellipse around the sun. All planets move in an ellipse around the sun.
What is precision?
- The more precise a theory the more falsifiable it is.
- Example: Planets move in ellipses around the sun. Planets move in closed loops around the sun.
- Operational definition –describes exactly what the variables are and how they will be measured.
What is Parsimony?
- Among competing theories, the one that makes the fewest assumptions should be favoured. -Occam’s Razor →simple theories are preferred
- Example: Event: It is raining, and I saw a bright flash through my curtains. Explanation A: There was lightning. Explanation B: Some is trying to take pictures of me
Is it good to increase falsifiability?
- The more falsifiable a theory the better.
- Theories should become more and more falsifiable: More content and more informative
- A replacement theory should be more falsifiable than that which it replaced.
- Example: All bread nourishes. Bread, with the exception of that particular batch of bread produced in the village in question, nourishes. All bread nourishes except bread made from wheat contaminated from a fungus
What is fruitfulness?
- Has the theory led to new empirical discoveries?
- Does the theory lead to scientific progress?
- Falsifying theories and offering more precise and falsifiable replacements leads to new discoveries
- Example: Theory: Bats have weak eyes, but they are sufficient to see. Test: Blindfold bats and release them in room. Theory: Bats use their ears to avoid obstacles in the dark. Test: Plug the ears before releasing them. Theory: The bat uses echoes of its own squeaks rebounding. Test: Gag before releasing them
What is Confirmation bias?
tendency to seek confirming evidence
What are the problems with falsifiability?
Do not give up too easily: Newton’s laws of physics, the motion of Uranus, and the discovery of Neptune
What are ad hoc modifications?
- Ad hoc modification = changes to a theory that makes the theory less falsifiable
- What are allowable and unallowable modifications?
- Example: Fingerprint analysis
Who was Thomas Kuhn (1922-1996)?
- American physicist
- The structure of scientific revolutions
- Science is social activity
- Scientific Paradigm -set of common views of what the discipline is about and how problems should be investigated
