Class 10: Beyond perception

Methodology of Scientific Research

Andrés Aravena, PhD

March 21, 2024

Our senses can fool us

Immediate perception is good, except for

  • Optical illusions
  • Dreams
  • Hallucinations
  • Incomplete information
  • Pattern matching
  • Anthropomorphism

Distrust of senses

This leaded some people to believe that

“The body is dirty,
the soul is pure”

We need a “Plan B”

Plan B: Rational view

“Truth emerges from Reason

Idea represented by

  • Aristotle
    • logic syllogism
  • Euclid
    • geometry
    • axioms
    • theorems

Both aim to Separate Essence from Accident

But people can disagree…

It is common that philosophers disagree on their reasoning

  • They start from different hypotheses

  • They use the same words with different meanings

  • Their logic may not be solid

Maths solves this problem…

  • Hypothesis are clearly defined

  • Meaning of words are clearly defined

  • Uses well defined logic

…loosing contact with reality

Math is not about nature

It is all imaginary

Math only exists in our minds

Math is the most
humanist discipline


Rational thinking chemically pure

  • Feelings are not important, but truth feels good

  • Beauty is not important, but truth is beautiful

  • Abstraction disconnects from details

Separate Essence
from Accident

Correct reasoning is hard

The priority of our organism is

  1. Survival
  2. Save energy

So fast and instinct decisions are automatic

  • Most of the time we use the cheap intuitive system
  • Rational thinking (i.e. math) is not spontaneous

Instead of thinking, we “guess” or “ask someone else”

We take a shortcut

Plan C:
Truth from authority

“My dad is always right”

“Someone told me…”

Most of our knowledge comes from other people

  • Our parents

  • Our professors

  • Books

  • Scientific papers

  • Authority

“Truth from authority”

  • Medieval/feudal point of view

  • “Aristotle was the most intelligent man,
    he must have been right”

  • Knowledge is in “The Books”

  • Catholic church was built on this premise

People with power liked it

“The boss is always right about everything”

But how do they know?

This approach just delays the question

If our knowledge comes from someone else,
how did they know what is true?

Is rationality enough?

“Aristotle was the smartest man”

In medieval times, his theories were taken as truth

He was indeed a smart person, but…

“Males have more teeth than females in the case of men, sheep, goats, and swine; in the case of other animals observations have not yet been made”

he said

“History of Animals” by Aristotle
Do Men Have More Teeth? (Aristotle Was Wrong; You Could Be, Too)” by Grayson Quay

Extramission theory of vision

  • A theory accepted by Plato, Euclid and others
  • The eyes emit a “gentle” fire that touches the objects we see
  • We need to mix with another fire to see
    • like the sun
    • or a campfire

Fire, earth, water and air

“All material is a mix of these four elements”

For example

  • Wood is made of fire and earth.
  • Burning wood separates the fire
  • Leaving only earth (ash) behind

Celestial spheres

People believed that Earth was inside crystal spheres

  • Stars were in a steel sphere
  • When we find a fallen star, it is made of steel
  • We get the words “sideral” and “siderurgy”
  • What element was between the spheres?

Humor theory

Excess or deficiency of any of four distinct bodily fluids (humors) influences temperament and health

  • Classic Greek, Roman, Persian and Indian (Ayurveda)
    • Blood, Yellow bile, Black bile, Phlegm
  • Hippocrates (born c. 460 B.C.E.)
  • Galen (b. 129C.E. Asia Minor)


Used until the 19th century to “heal” people

About Aristotle, and others like him

“Although he was twice married, it never occurred to him to verify this statement by examining his wives’ mouths.”

Bertrand Russell

Why Aristotle made such mistake?

“To the Greeks of Aristotle’s time, and for two thousand years afterward, scientific truth was best discovered and expressed by deducing the nature of things from a set of self-evident premises.”

Neil Postman in “Amusing Ourselves to Death”

Smart people can believe crazy things

Today: Conspiracy theories

  • Apollo moon landings were staged
  • Weather control
  • GMO research is fake
  • Roswell UFO incident
  • Area 51
  • Kennedy assassination
  • 9/11
  • 5G controls minds
  • COVID vaccines have a chip to control us

Research Question

What other things are believed by smart people despite evidence on the contrary?

What Aristotle did not knew

The age of discoveries showed that the old books did not have all answers

  • What about America?

  • What about Australia?


Where is the Truth?

The Truth is Out There