
March 3, 2021
Chapter 1 “The Reach of Explanations” | TokCast with Brett Hall
Key Takeaways
- For most of the history of science, we mistakenly believed that we derive theories from our sensory experiences
- While essential to science, experience is not the source of theories
- Experience allows choosing between different theories that have already been guessed
- Scientific theories are about reality, which is often different from anyone’s experience
- Astrophysics is not about our experience of stars, but about what stars are
- Karl Popper claimed (and most people agree) that for theories to be “scientific” they must be testable
- But testability is not enough because prediction is not the purpose of science
- If you predict the outcome of a magician’s trick (prediction is testable), it does not mean you understood the trick
- But testability is not enough because prediction is not the purpose of science
- The quest for “good explanations” is the basic principle of Science
- A good explanation is hard to vary because all the details play a functional role
- Good explanations are often simple or elegant (Occam’s razor)
- Some explanations can solve problems beyond those that were created to solve
- The theory reaches out from its finite origins in one human brain to infinity
Intro
- TokCast (TOK=Theory of Knowledge) is a podcast about the work of David Deutsch
- David Deutsch (@DavidDeutschOxf) is a British physicist known for pioneering the field of quantum computation, he also made important contributions in the fields of philosophy, economics, politics, mathematics, and more
- Check out David’s website
- Host: Brett Hall
- Check out Brett’s website
- In this episode, Brett reads and discusses some passages from the first chapter of David Deutsch’s book The Beginning of Infinity, “The Reach of Explanations”
Where Do Theories Come From?
- For most of the history of science, we mistakenly believed that we derive theories from our sensory experiences
- Making observations from Nature to derive knowledge
- This is known as empiricism
- Empiricism brought progress in science by denying the knowledge of priests and religions
- In reality, scientific theories are not “written in Nature”, they are guesses created by human minds
- While essential to science, experience is not the source of theories
- Experience allows choosing between different theories that have already been guessed
- Empiricism had not seriously been challenged until Karl Popper in the mid-1900s
Critiques to Empiricism and Inductivism
- How can your experience about something help you derive knowledge about something you didn’t experience?
- How can you learn about physics on Mars from experiments done on Earth?
- To reach conclusions about what was not experienced, empiricism relied on inductivism
- If you repeatedly have similar experiences under similar circumstances, you can predict that the pattern will continue
- You expect the sun to rise tomorrow morning because you’ve seen it do so every day
- If you repeatedly have similar experiences under similar circumstances, you can predict that the pattern will continue
- Inductivism intends to create theories from experience
- Yet, scientific theories are about reality, which is often different from anyone’s experience
- Astrophysics is not about our experience of stars, but about what stars are
- Yet, scientific theories are about reality, which is often different from anyone’s experience
- Inductive inferences tend to assume that the future will resemble the past (or the unseen resembles the seen)
- In reality, the future is unlike the past
- Science consistently creates phenomena that were never experienced before
- Humans flying or nuclear bombs are examples
- Even if you experience the same thing every day, you can’t be sure that it will be the same tomorrow
- In reality, the future is unlike the past
- “Induction is irrationality, it is a way of generalizing” Brett Hall
- Hasty generalization is a logical fallacy that relies on induction
- This kind of faulty reasoning leads to racism
- Hasty generalization is a logical fallacy that relies on induction
Justificationism, Fallibilism, and The Enlightenment
- There is a misconception that knowledge “needs” authority to be genuine
- This is known as Justificationism
- For something to be true, it needs to be designated as true by a reliable authority
- Instead of asking “How do we know”, it makes us ask “What authority says so”
- This is known as Justificationism
- The opposing position to Justificationism is called Fallibilism
- Since people, who are fallible, are constructing knowledge, we can never be sure that anyone found the perfect theory
- Fallibilism is not just about the rejection of authority
- The fact that you can be wrong, implies that there is an objective truth, but we can never be sure of it
- Some theories have already been proven false
- Objective progress is done by proving more theories false
- Criticism of theories gets us closer to truth
- The Enlightenment was a revolution in how people sought knowledge
- People stopped relying on authority and developed a tradition of criticism
What Differentiates Science from Not-Science
- Karl Popper claimed (and most people agree) that for theories to be “scientific” they must be testable
- A scientific theory must make predictions that could be proven false
- While scientific theories can’t be derived from experience they can be tested by experience
- But, testability alone cannot be enough to demarcate science
- Testable theories have always existed
- Cavemen trying to make better weapons could have a theory and test it
- Testable theories have always existed
- Testability is not enough because prediction is not and cannot be the purpose of science
- If you predict the outcome of a magician’s trick (prediction is testable), it does not mean you understood the trick
- Science requires an explanation
- Ancient Greeks used to correctly predict winter through the myth of the Goddess Persephone, going to the Underworld every six months
- A totally different myth about another God could have also explained it
- When different theories can be used equally to explain a phenomenon, choosing one theory over the others is irrational
- Even if they make testable predictions, they are not scientific, they are myths
- The quest for “good explanations” is the basic principle of Science
- “We should conclude that a particular thing is real if and only if it figures in our best explanation of something” David Deutsch
- A good explanation is hard to vary because all the details play a functional role
- In the axis tilt theory of the Earth, if you tilt the axis by more or less than what they are, the seasons would be different
- Good explanations are also hard to find
- The harder they are to find, the harder they are to vary once found
- Good explanations are often simple or elegant (Occam’s razor)
- Bad explanations often contain superfluous features or arbitrariness
- Removing the superfluous leads to better explanations
- Extremely good explanations are the ones that passed many stringent tests
- That’s why testability is still an essential feature of Science
The Reach of Explanations
- How can we know so much about unfamiliar aspects of reality?
- Some explanations can solve problems beyond those that were created to solve
- Example of the axis tilt theory
- It was initially proposed to explain the changes in the Sun’s angle of elevation during each year
- Then it also explained seasons, why tropical regions don’t have them and why the sun shines at midnight in polar regions
- The theory makes predictions even about planets that we’ve never seen
- The theory reaches out from its finite origins in one human brain to infinity
- It was initially proposed to explain the changes in the Sun’s angle of elevation during each year
- We only find out about an explanation’s reach after we have the explanation
- It has nothing to do with induction or extrapolating a theory