Class 11: What is Science?

Methodology of Scientific Research

Andrés Aravena, PhD

March 26, 2024

The Truth is Out There

Science is the synthesis of the Empirical and Rational approaches

The Big Picture of Science

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 Pseudo-Science

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 Pseudo-Science
  • Science is the result of applying the scientific method
    • This is the approach we will take

An operational definition of Science

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”


Observations depend on previous Knowledge

We use tools and methods developed earlier

This may result in blind spots

The first step is to Find Patterns

We can only explain events that can be repeated

If it only happens once, we cannot study it

Explanations are stories based on models

An explanation is a story, coherent with a model

The goal of Science is to explain Nature

Valid models should produce new Predictions

We should be able to test these predictions

If the predictions fail, we learn that our model is wrong

If they do not fail, we design another experiment

Observations and Test can be done in the lab

Wet lab is only part of science

The key parts happen in our brains

Knowledge” means Published

If your results are not peer-reviewed and made public, then it is not science

This is what happened to alchemists

Since they never published their results, they could not improve their models

Nobody remembers Newton’s alchemy work

Everybody knows what he published

Peer review”: Nobody is better than us

“Peer” means people like us

There is nobody more qualified to have an idea

Even if you are a famous Nobel prize winner, you can be wrong

We evaluate the ideas, not the people

Authority is not relevant

The key is to ask
Good Questions

This is the most important point

In Summary

Science is

  • About “outside”
  • About observable 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

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.


In this framework, Technology is about Things Built by Humans

  • Machines
  • Processes
  • Engineers
  • Know how…

Scientists see the world as it is, and ask “why?”

Engineers see the world as it could be, and ask “why not?”

Four Paradigms of Science

according to Microsoft Research

1. Empiric (since prehistoric times)

  • observation of isolated facts
  • description of related facts
  • e.g. Botany, naming stars,
  • Represented by the Arab astronomers, Galileo, Tycho Brahe, Carl Linneaus

2. Theoretical (Renaissance)

  • Abstract models and theories
  • Usually expressed in mathematical formulas
  • Correct predictions validate the models
  • e.g. Mendel laws of inheritance, Darwin natural selection theory, Kepler law of planet’s motion, Newton’s law of Gravity

3. Simulation Based (Mid 20th century)

  • Models that cannot be expressed in formulas
  • Formulas that cannot be solved
  • e.g. Protein structure prediction, three body problem, galaxy modeling
  • Computational Astronomy, Computational Biology

Represented by John Von Neumann

4. Data Based (21st century)

  • Discovering patterns hidden in data
  • Huge volumes of data
  • Complex interactions
  • e.g. Bioinformatics, Astroinformatics, Data mining
  • Big Data, Machine Learning

There are no answers, only better questions to ask