Basic Scientific Reasoning 10/21/2004

Reminder… Collect the Aristotle / Debate assignment! Also: a clarification- the final grade in the class is based on the points earned with each assignment, NOT the letter grade!

That is: NOT: points -> letter grade -> percentage added together = Final grade. IS: Points added together -> percentage over total points possible = final grade.

And: 2 slight changes to syllabus 1.Final paper increased in weight: 1.1 st paper =75 pts 2.Midterm = 75 pts 3.Labs = 5pts each x 15 = 75pts 4.Attendance = 1pt each + Participation (close to 10% of total– on this calculation, participation will be around 60pts) 5.2 nd paper = 125 pts. 6.Final = 125 pts. 7.Random assignments = 10 pts each. 8.Total = at least 605 pts (possibility of more 10 pt assignments & participation weight)

2 nd slight change: Week 13 lab say’s “Start writing” BUT The calendar has 2 nd paper due the Monday of week 13! What I intended was to collect the 1 st, rough draft as lab on week 13 – but that’s Thanksgiving! Rough draft due Nov 29, Monday after Thanksgiving Final draft due Dec 10, last day of class.

Outline What is Science? Problem Verification & Falsification The Quine-Duhem Thesis: Christine Ladd-Franklin’s falsification of Helmholtz’s theory of color perception.

What is Science? Astrology Psychoanalysis Physics Psychophysics Mathematics Phrenology Biology Psychology Scientology Economics Cognitive Science Chemistry Sociology History Cognitive Ethology

Defining Science Is science defined by its method of reasoning? –Its results? –The phenomena it studies? –An attitude towards evidence? –A certain methodology? –Scientists? –The power relationships in which it is embedded? –Its value to the larger culture? –Use of (grounding on) mathematics?

Why should I care? ‘Science says that…’ ‘The top scientists think that…’ States that have (or are) debated teaching creationism in elementary science education: –Georgia –Kentucky –Pennsylvania

A Demonstration So how does ‘real’ science work? Recall the problem

Preliminary Lessons from Science is an activity of real people who work in a social environment 2.There is nothing ‘special’ about the methods of reasoning used in science 3.When scientists ‘converge’ on the answer is often determined by social factors.

Structures of Reasoning on display in Verification - Affirming the consequent: IF P THEN Q Q THEREFORE, P Example: IF aliens killed JFK, THEN there would be questions regarding the ‘single-shooter’ theory. There are questions regarding the ‘single-shooter’ theory. THEREFORE, aliens killed JFK.

Verification IF the rule is ‘Any three numbers such that x < y < z’, THEN will fit does fit THEREFORE, the rule is ‘Any three numbers such that x < y < z’ IF the rule is ‘Any three numbers (x, y, z > 0) such that y = x+2 and z = y+2’, THEN will fit does fit. THEREFORE, the rule is ‘Any three numbers (x, y, z > 0) such that y = x+2 and z = y+2’

Verification’s Problems Can’t ensure the truth of the theory that entails the verified prediction Can’t distinguish between two theories that both entail the verified prediction

Structures of Reasoning on display in Falsification - Modus Tollens: IF P THEN Q NOT-Q THEREFORE, NOT-P Example: IF aliens killed JFK, THEN Jack Ruby is an alien. Jack Ruby is NOT an alien. THEREFORE, aliens did NOT kill JFK.

Falsification Application to 2-4-6: IF the rule is ‘any three numbers (x,y,z) such that x > y < z’, THEN the sequence ‘4-2-8’ will fit. The sequence does NOT fit. THEREFORE, the rule is NOT ‘any three numbers (x,y,z) such that x > y < z’ IF the rule is ‘any three symbols (x,y,z) such that x < y < z in their standard order’, THEN the sequence ‘a-b-c’ will fit. The sequence a-b-c does NOT fit. THEREFORE, the rule is NOT ‘any three symbols (x,y,z) such that x < y < z in their standard order’

Falsification’s Virtues & Vices Still can’t ensure the truth of the theory that entails the verified prediction CAN distinguish between two theories, so long as there is at least one prediction that is entailed by one & NOT by the other.

Real scientists don’t work that way.

Quine-Duhem Thesis Any hypothesis can be defended in light of any evidence. (if you’re willing to make “drastic enough adjustments elsewhere” in your system of beliefs.) IF Hypothesis is true, THEN Prediction. Prediction is NOT true THEREFORE, the hypothesis is NOT true VALID

Dogmatism Any proposition can be made consistent with any scientific theory, if one tries hard enough –Gender, Intelligence, Variability and Pre- and Post-Darwin Biology –Myths of Gender by Anne Fausto-Sterling

Here, the Devil lurks IF my Hypothesis is true, Prediction is NOT true THEREFORE, at least one of (1) – (N) is NOT true (1) AND My apparatus works, (2) AND My experiment is correctly designed, (3) AND My subject is of interest to others, … THEN, prediction. (N) AND ….

(Brief) History of Color Science Basic Schema:

Hermann von Helmholtz ( ) Short = Purple Middle = GreenLong = Red

Historical Note: In 1877, Ladd-Franklin became the first woman to attend (albeit unofficially) Johns Hopkins where she studied mathematics. She wrote a dissertation under the supervision of C.S. Pierce. It was published in 1883, but her Ph.D. was not awarded until 1926! Even though she had studied under Helmholtz and had published a great deal in psychological journals, she was never admitted to the American Psychological Association meetings to present her papers. While she lectured at John Hopkins, Columbia, Clark, Harvard and Chicago, she never held an official academic post, and she was rarely paid. Her book Color and Color Theories was finally published in 1929, one year before her death.

Ladd-Franklin ( ) IF stimulating the long-wavelength cone yields a red experience, and stimulating the middle-wavelength cone yields a green experience, THEN stimulating both the long and middle- wavelength cone would…. yield an experience of reddish-green

L-F’s argument (≈1892) IF stimulating the long-wavelength cone yields a red experience, and stimulating the middle-wavelength cone yields a green experience, THEN stimulating both the long and middle- wavelength cone would yield an experience of reddish-green Stimulating L and M yields an experience of yellow. THEREFORE, Helmholtz’s theory is NOT true Yellow does NOT look like reddish-green. THEREFORE, yellow is NOT reddish-green. Good Argument Right?

Why not? “Helmholtz deemed it illegitimate or at least untrustworthy to draw conclusions as to physiological processes from the direct psychological character of the sensations” -Von Kries

Q-D for Helmholtz IF stimulating the Long-wavelength cone yeilds a red experience, and stimulating the middle-wavelength cone yields a green experience, THEN stimulating both the Long and Middle- wavelength cone would yield an experience of reddish-green Stimulating L and M yields an experience of yellow. THEREFORE, Helmholtz’s theory is NOT true THEREFORE, Yellow is NOT reddish-green. Yellow does NOT look like reddish-green. BUT: One cannot draw conclusions about the physiology of color from this fact, so it does not follow that: yellow is not reddish-green or greenish-red.

Note: The Gestalt Psychologist David Katz made the phenomenology of color appearance the starting point for a theory of color (1908).

Vindication: In 1957, Dorothea Jameson & Dale Hurvich proposed what is now called the ‘opponent-processing’ model of color perception. According to it, colors are given by mixing 4 primary colors which are arranged in opponent pairs: RedGreen BlueYellow This is now the dominant theory in color science

Falsification (finally) In 1977, Edwin Land produced a falsification: The particular relationship between the stimulus of the L, M and S cones is both NECESSARY and SUFFICIENT for determining a particular color sensation. (Given trichromatic perceivers and normal conditions) Helmholtz (sufficiency) Produce a case where two objects stimulate the L, M and S cones in exactly the same way, but produce two different color sensations (necessity) Produce a case where two objects stimulate the L, M and S cones in different ways, yet produce the same color sensation. Two falsifications required:

Mondrians 5.8 (L) 3.2 (M) 1.6 (S) These values held for red, green and blue patches, yet the patches still appeared red, green and blue! 5.8 (L) 3.2 (M) 1.6 (S)

Tristimulus values sufficient for color appearance According to the Helmholtz theory, IF objects reflect the same tristimulus values, THEN they will appear to be the same color. A patch in the first Mondrian reflects the tristimulus values of 5.8(L), 3.2 (M) and 1.6 (S), yet looks red. A patch in the second Mondrian reflects the tristimulus values of 5.8(L), 3.2 (M) and 1.6 (S), yet looks blue. (from 1) IF the Helmholtz theory is correct, THEN the patch in the first Mondrian will appear to be the same color as the patch in the second Mondrian. They do NOT appear to be the same color. THEREFORE, the Helmholtz theory is NOT correct.

Tristimulus values necessary for color appearance According to the Helmholtz theory, IF two objects appear to be the same color, THEN they will reflect the same tristimulus values. Before Land turned the projectors on, the red patch looks red. After Land turned the projectors on, the red patch looks red. (from 1) IF the Helmholtz theory is correct, THEN the patch that continues to look red must reflect the same tristimulus values when the projectors are on & off. The patch that continues to look red does NOT reflect the same tristimulus values when the projectors are on as it does when they are off. THEREFORE, the Helmholtz theory is NOT correct.

Helmholtz’ response (from 1) IF the Helmholtz theory is correct, THEN the patch that continues to look red must reflect the same tristimulus values when the projectors are on & off. The patch looks red w/ the projector OFF and it reflects tristimulus values x, y, z THEREFORE, the Helmholtz theory is NOT correct. The patch looks red w/ the projector ON and it reflects tristimulus values a, b, c BUT: One cannot draw conclusions about the physiology of color from this fact, so… The patch looks red w/ the projectors OFF, but it is really isn’t. (or vice versa)

Timeline 1856: Helmholtz proposes his theory 1892: Christine Ladd-Franklin formulates her argument. 1957: Theory change following Jameson & Hurvich 1977: Land’s Falsification 64 years!20 years 1908: Gestalts.

Why Theory Change? New Technology (Galileo's Telescope) Socio-cultural factors (Ladd-Franklin) Mathematics (Jameson & Hurvich)

Alternatives for Demarcation 1.Verification 2.Falsification 3.Lakatos’ ‘Progressive v. Degenerative’ 4.Sociological factors 5.Explanation in terms of mechanism.