"Scientific Proof" - an Idea Debunked

1. Let us find out what "scientific proof" really means
. . . and what it doesn't

     We can relate this to 
         daily life
         Earth 2100
         or whatever we feel like discussing

A starting point:
    What is the difference between
    science
    and
    mathematics?




2. Math:
prove new things
based on
existing knowledge

Mathematical reasoning is:
deductive

• 1+1=2
• 2+2=4
• Therefore,
• 1+1+1+1=4
• (proof by substitution)

• All men are mortal
• Socrates is a man
• Therefore,
• Socrates is mortal
• (proof by "syllogism")

• Deduction can prove things
• Mathematics uses deduction
• Therefore,
• mathematics can prove things
• (proof by syllogism again!)

3. Science is different from math!

• Science is based on:
• induction
• (not deduction)
• All apples that break off the tree,
• fall down
• Therefore, if I shake this apple tree,
• and an apple breaks off,
• it will fall down
• Not a proof!
• Can you think of a counterexample?

• That which goes up has always come down
• Therefore, if I throw this up, it will come down
• Not a proof! Can you think of a counterexample?

4. Science needs more than induction

Humankind has always sought reasons

Scientists call those reasons
"theories" and "hypotheses"

Theories are the BIG ones

• relativity
• evolution
• continental drift/plate tectonics

Hypotheses are the >little< ones

• If the ground gets waterlogged,
• water will get into my basement
• IFSC majors 
• are more employable 
• than physics majors

Conclusion. . .
Math proves;
science does not prove!

Science disproves
(by refuting inductive "truths")

Science explains
(using theories)

Science predicts
(because the theories predict)

5. The phrase "scientific proof" makes no sense!

• Science does not prove things!
• It explains things and finds evidence
• If only everyone actually knew that
• Not just you, but also
• reporters,
• spokespeople,
• politicians
• the average person

6. Example: Global Warming

7. Example: Various medical advice

8. Example: US legal system

9. Example: More speculative science

                    ("Do toxoplasma germs control humanity?")