PSC482G, Spring 2000
Assignment 4, due Friday 28 January 2000
Critical thinking 3
Read: “Science, pseudo-science, and falsifiability,” by Karl Popper, and “A modified scientific method for the JFK assassination.”
Answer
these questions:
Let us have a practice run on using the pattern of critical thinking described
at the end of the essay on the modified scientific method. For basic data, we
will use the 25 pieces of evidence from Assignment 3. I give you the question
and the evidence, and you do everything else. By “everything else,” I mean
taking the evidence through as many of the steps of the modified scientific
method as you can, recognizing that you are still in the very early stage of
studying the assassination and how to think about its evidence. Good luck!
1. The question: Who killed John F. Kennedy?
2. List all preconceived answers, now matter how bizarre or biased.
3.
List all relevant evidence. (Use this partial list. Feel free to supplement it
with other evidence you may know.)
1. Three spent cartridges were found in the sniper’s nest
on the sixth floor of the Depository.
2. One entrance wound was found in the rear of JFK’s head;
one in his back.
3. The Zapruder film shows that Kennedy’s head moved
forward, then back.
4. Immediately after the shooting, police and the crowd
rushed up the grass toward the picket fence.
5. Many witnesses recalled hearing shots from the direction
of the grassy knoll.
6. Many witnesses heard shots from the direction of the
Depository.
7. Howard Brennan saw a sniper fire the last shot from the
Depository.
8. Metal fragments in JFK’s head formed a cone opening from
the small rear wound to the large missing area of skull on the right side.
9. The area of the limousine in front of the Kennedys was
covered with blood and tissue.
10. Most witnesses heard between two and five shots.
11. At least two persons in Dealey Plaza smelled gunpowder at
ground level.
12. Extreme enlargement of Mary Moorman’s Polaroid photo
shows two or three figures behind the picket fence on the knoll.
13. As William Morrow wrote in his two books, he bought three
identical Mannlicher-Carcano rifles for use in the assassination.
14. Of the three large bullet fragments recovered, two were
traceable ballistically to Oswald’s rifle to the exclusion of all other
rifles.
15. The bullet recovered from the stretcher in Parkland
Hospital is both traceable to Oswald’s rifle and pristine.
16. Between the hits to Kennedy and Connally’s bodies,
there was insufficient time for a shooter using Oswald’s rifle to refire.
17. The diffuse cloud of fragments from JFK’s head moved
forward, upward, and to the sides.
18. A motorcycle policeman to the left rear of the limousine
was hit on his right side by fast-moving fragments from JFK’s head.
19. One witness saw a man carry a rifle up the grassy knoll
shortly before the assassination.
20. As Oswald said, he was eating lunch in the second-floor
lunchroom at the time of the shooting.
21. A photo of the Depository, when greatly enlarged, shows a
human figure in another sixth-floor window.
22. A number of witnesses saw a man behind the picket fence
break down a rifle immediately after the shooting, put it into a case, hand the
case to another person, and stride rapidly away from the scene.
23. Footprints were found in a muddy area behind the grassy
knoll.
24. Beverly Oliver, the “babushka lady” who was just to
the left of the president’s limousine at the time of the head shot, looked
right down the barrel of a rifle being fired from the top of the knoll.
25. Nearly all the medical personnel at Parkland Hospital saw
the fatal wound in Kennedy’s head at the rear, not on the right side as the
autopsy photos show.
3a.
Divide the evidence into strong and weak, where “strong” means critically
testable” (falsifiable). To the extent that you know which of the strong
evidence has been validated, use only it.
3b. Proceed with the tested and validated evidence only.
4. List all possible answers, however unlikely, consistent with the facts in 3b.
5. Choose the simplest answer consistent with all the facts.
6.
Test your answer rigorously against its consequences (predictions) or against
new evidence gathered explicitly for the purpose.
a. Consider the answer proven if it passes the test and no
other answer is possible (for example: the earth is round).
b. Retain the answer if it passes the test but other answers
are possible.
c. Reject the answer if it fails the test.
7. If the answer was rejected, continue testing progressively more-complex answers until one is found that survives.
8. Retain this answer as a working hypothesis until new evidence forces you to reject it.
Be sure to show your answers for steps 2–8.