Class 3: What is Science?

Methodology of Scientific Research

Andrés Aravena, PhD

March 3, 2022

The Truth is Out There

Science is the synthesis of the Empirical and Rational approaches

Everybody wants to be “Scientific”

Many people wants to be “scientific”, such as

  • Philosophical Sciences
  • Religious Sciences
  • Hidden Sciences
  • Supernatural Sciences
  • Political Sciences

Some of these are better called PseudoSciences

Kinds of “Official” Sciences

Exact Sciences
Mathematics. Truth abut imaginary things.
Positive Sciences
what is “put” outside.
the observer is not part of the system.
“objective reality”.
Natural Sciences
Reality is the Nature.
Social Sciences
Reality is the Human Society.

Since there is no “authority”, nobody can make an “official” definition of Science

There are two ways to “define” Science

  • Science is what scientist do
    • very much used in practice
    • but kind of useless definition
    • does not allow to separate Science from PseudoScience
  • Science is the result of applying the scientific method

An operational definition of Science

test test prediction prediction test->prediction explanation explanation prediction->explanation nature nature observation observation nature->observation pattern pattern observation->pattern knowledge knowledge observation->knowledge question question pattern->question question->explanation peer-review peer-review knowledge->peer-review peer-review->test

Scientist work is to understand Nature

We start by Observing Nature, usually measuring values.

These are exploratory experiments.

We study this in other courses.

The thing we study must be reproducible, and we need to see that repetition.

We can find them using plots, linear models, clustering, etc.

This is the most important part.

Good answers to bad questions are useless.

Good questions are good, even if we don’t have answers

We answer these questions using models and explanations

Valid models should make predictions that we can test in the lab…

These are validation experiments.

If the results do not match the prediction, we know that the explanation is wrong. Two steps back.

Now we publish our data and model, so other scientists validate or reject it.

The final validation is to be published.

If the paper is accepted and published, our work becomes part of our shared human knowledge.

The goal of Science is to produce new Knowledge.

When we observe Nature we use our previous Knowledge

We look for new Patterns that raise new Questions.

“Noise becomes Signal”


  • Our Observations depend on our previous Knowledge
  • The first step is to Find Patterns
  • The key is to ask Good Questions
  • Explanations are “models”, in a broad sense
  • Valid models should produce new Predictions
  • Observations and Test can be done in the lab
  • Knowledge” means Published

Characterization of Science

  • About “outside”
  • About visible things
    • Things that you can measure
  • Provides Explanations
    • They must be Logic and Coherent
  • Peer reviewed
  • Replicable

Assumptions of Science

  • There is an “objective reality” outside us
  • The reality has some rules
    • It is not (completely) random. There are rules
    • The rules are “logic”
    • The rules do not change
  • We may not see the rules directly
  • We can (in theory) discover these rules using reason
  • Authority is not relevant


In this framework, Technology is about Things Built by Humans

  • Machines
  • Processes
  • Know how…

Homework (part of midterm exam)

Using any recording device (paper, cell phone, etc), take note of the questions that you can ask about what you see every day

Especially about questions that you don’t know the answer

For example “Does Technology derive from Science?”

There are no answers, only better questions to ask