What Is The Scientific
Method?
Chapter 4
Why Do Seedpods Fall?
Why Do Seedpods Fall?
•Because of gravity?
–The Law of Gravity
•Laws only describe. They do not
explain.
Why Do Seedpods Fall?
• No theory has ever been invented
that explains gravity without leading
to non-contradicted predictions.
Why Do Seedpods Fall?
• Today we still do not know why
seedpods fall.
Can Explanations Be
Proved True?
• Prove: To establish as true beyond
any possible doubt.
• Disprove: To establish as false
beyond any possible doubt.
Can Explanations Be
Proved True?
Can Explanations Be
Proved True?
•If . . . the sun orbits the Earth each
day from east to west,
•and . . . we observe the sun's
movements tomorrow,
•then . . . the sun should be seen rising
in the east, crossing the sky, and
setting in the west.
Can Explanations Be
Proved True?
Can Explanations Be
Proved True?
•If . . . the Earth rotates each day on
an axis from west to east,
•and . . . we observe the sun's apparent
movements tomorrow,
•then . . . the sun should be seen rising
in the east, crossing the sky, and
setting in the west.
Can Explanations Be
Proved True?
•Because explanations come from
human imagination, two or more might
lead to the same prediction.
•We need to set up planned tests with
different predictions.
Can Explanations Be
Disproved?
•If . . . cards with vowels on one side
have even numbers on the other side,
•and . . . we turn over the 7 card,
•then . . . we should find a consonant.
Can Explanations Be
Disproved?
Can Explanations Be
Disproved?
•But. . . suppose we turn over the 7
card and find a vowel.
•Therefore . . . we would have a card
with a vowel on one side and an odd
number on the other, which would
break the rule. DISPROVED RULE.
Can Explanations Be
Disproved?
Can Explanations Be
Disproved?
•If . . . grass is not growing under tree
B because it is not getting enough sun,
•and . . . some of tree B's branches are
cut off, permitting more sunlight to
reach the ground,
•then . . . the grass under tree B should
grow.
Can Explanations Be
Disproved?
•But. . . after the branches are cut off,
the grass under tree B does not grow.
•Therefore . . . the explanation must be
false, right?
•DISPROVED, right?
•WRONG!
Can Explanations Be
Disproved?
•A mismatch between prediction and
results gives two possibilities
–explanation is wrong OR
–test is faulty
•Disproof is not possible!
What Are the Steps in
Doing Science?
The Scientific Method
The Scientific Method
1-Puzzling observation made
2-Causal question raised
3-Hypotheses created (analogy)
4-Plan test (Assume hypothesis is
true)
5-Predict results
6-Run planned test
7-Results compared to prediction
8-Draw a conclusion
9-Repeat for all hypotheses