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Critical Rationalism (CR) – An Introduction 
Table of Contents
1-7: Context, Community & History
8-10: WHAT IS IT?
11-22+: Key Concepts
Coming soon:
- Deutsch's key ideas
- Common misconceptions
- Crit rats VS bay rats VS post-rats VS meta-rats
0/ https://twitter.com/JeffLadish/status/1298164099595923457
Table of Contents1-7: Context, Community & History
8-10: WHAT IS IT?
11-22+: Key Concepts
Coming soon:
- Deutsch's key ideas
- Common misconceptions
- Crit rats VS bay rats VS post-rats VS meta-rats
0/ https://twitter.com/JeffLadish/status/1298164099595923457
Critical rationalism is a theory of how knowledge grows and how information can flow.
A ton of consequences pop out of it — from politics to education, from how to do science to how to be happy, etc. — so 'critical rationalism' is also the broader worldview about all that.
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A ton of consequences pop out of it — from politics to education, from how to do science to how to be happy, etc. — so 'critical rationalism' is also the broader worldview about all that.
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CONTEXT
You may've seen the 'crit rats' on Twitter, in the context of LessWrong rationalists/post-rats/meta-rats/rationalist-adjacent circles.
We've existed for a while but only became 'rationalist-adjacent' in 2017. Mostly separate/parallel before.
2/ https://twitter.com/reasonisfun/status/939293937545699328
You may've seen the 'crit rats' on Twitter, in the context of LessWrong rationalists/post-rats/meta-rats/rationalist-adjacent circles.
We've existed for a while but only became 'rationalist-adjacent' in 2017. Mostly separate/parallel before.
2/ https://twitter.com/reasonisfun/status/939293937545699328
Critical rationalists have been around for nearly 100 years. It developed out of a different tradition from LessWrong 'rationalism' (which is really more empiricist than rationalist—historically, these were opposing views). It had its own communities, pre- and post-internet.
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HISTORY
It was started by 20th century philosopher Karl Popper (badass—he went from carpenter to teaching himself Ancient Greek in order to make his own translations of the Presocratics).
His main opponents were positivists and empiricists (both of which LW veers into btw).
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It was started by 20th century philosopher Karl Popper (badass—he went from carpenter to teaching himself Ancient Greek in order to make his own translations of the Presocratics).
His main opponents were positivists and empiricists (both of which LW veers into btw).
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It was always pretty niche. Popperians would buzz around saying things like, "Induction is a myth!" and "I don't need to justify myself to you!" [see / to join the in-joke].
Mostly no one listened (so they complained).
The community was mainly old students of Popper until…
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Mostly no one listened (so they complained).
The community was mainly old students of Popper until…
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The guy who invented the idea of quantum computers, @DavidDeutschOxf, got interested in Popper because he was trying to solve problems in physics.
Seeing its depth, he applied it to other fields and areas of life (including education, creating @TCSphilosophy).
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Seeing its depth, he applied it to other fields and areas of life (including education, creating @TCSphilosophy).
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Communities popped up around @DavidDeutschOxf: he was a deep and broad thinker, and wrote a popular book unifying the fields of computation, quantum theory, evolution and epistemology (The Fabric of Reality).
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1934 - Popper's 1st book published
[… academic communities, students, etc …]
1994 - online communities (TCS; 1995-Karl Popper Web)
1997 - Deutsch 1st book
2011 - Deutsch 2nd book ( https://www.thebeginningofinfinity.com/ )
2012 - Deutsch joins Twitter
2015 - Sam Harris podcast jumpstarts it
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[… academic communities, students, etc …]
1994 - online communities (TCS; 1995-Karl Popper Web)
1997 - Deutsch 1st book
2011 - Deutsch 2nd book ( https://www.thebeginningofinfinity.com/ )
2012 - Deutsch joins Twitter
2015 - Sam Harris podcast jumpstarts it
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Deutsch claims he's only "footnotes to Popper", but his fans insist he's meaningfully developed the ideas. (He did things like emphasise explanation, integrate it with transhumanist optimism, etc.)
So we just say 'CR' to mean 'Deutsch-lineage CR'.
(I'm working on a rebrand.)
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So we just say 'CR' to mean 'Deutsch-lineage CR'.
(I'm working on a rebrand.)
7/
WHAT IS CRITICAL RATIONALISM?"What is knowledge and how does it grow?"
Traditional epistemology says:
1) Knowledge is justified, true belief (JTB).
2) It grows by induction.
Popper says:
1) Knowledge is tentative solutions to problems.
2) It grows by correcting errors.
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Critical Rationalism in a nutshell:
• Realism
• Fallibilism (we can't know what's true, yet we *can* improve our theories)
• Start from existing knowledge (tradition)
• Error-correction
• Recasts everything as problems & problem-solving
• Evolution, but ideas not genes
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• Realism
• Fallibilism (we can't know what's true, yet we *can* improve our theories)
• Start from existing knowledge (tradition)
• Error-correction
• Recasts everything as problems & problem-solving
• Evolution, but ideas not genes
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Critical Rationalism opposes things like…
ESSENTIALISM
Definitions are circular.
EMPIRICISM
"Observation is theory-laden".
POSITIVISM
Not everything boils down to science; philosophy is meaningful even when untestable.
INDUCTION
Ideas are conjectured, not derived.
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ESSENTIALISM
Definitions are circular.
EMPIRICISM
"Observation is theory-laden".
POSITIVISM
Not everything boils down to science; philosophy is meaningful even when untestable.
INDUCTION
Ideas are conjectured, not derived.
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KEY CONCEPTS: POPPER Table of ContentsJustificationism - 12
Criticism - 13
Inductivism - 14
Conjecture - 15
Empiricism - 16
Essentialism - 17
Rationalism - 18
Rationality - 19
Fallibilism - 20
Problem - 21
Tradition - 22
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JUSTIFICATIONISM
If CR were against one thing, it's the idea that theories need to be justified, or verified, or 'probably true'.
Instead of assigning probability or certainty-level to theories, CR says a theory just needs to be better than its rivals. (Survive criticism.)
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If CR were against one thing, it's the idea that theories need to be justified, or verified, or 'probably true'.
Instead of assigning probability or certainty-level to theories, CR says a theory just needs to be better than its rivals. (Survive criticism.)
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CRITICISM
It's called 'critical' rationalism to contrast with justificationist or verificationist philosophies.
One can never prove a theory is true. There's a logical difference between refutation and confirmation. The content of a theory is what it *rules out*.
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It's called 'critical' rationalism to contrast with justificationist or verificationist philosophies.
One can never prove a theory is true. There's a logical difference between refutation and confirmation. The content of a theory is what it *rules out*.
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INDUCTIVISM
Induction is the idea that we gain knowledge through repeated observations. It has some logical flaws, known as the 'problem of induction'.
Popper solved it, by providing an alternative way knowledge grows; and wrote further disproofs, eg of Bayesian updating.
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Induction is the idea that we gain knowledge through repeated observations. It has some logical flaws, known as the 'problem of induction'.
Popper solved it, by providing an alternative way knowledge grows; and wrote further disproofs, eg of Bayesian updating.
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CONJECTURE
So where do we get theories?
We make them up.
We guess 'em. Any will do. Source is irrelevant.
What's important is what you do with guesses afterwards: Try to poke holes in them. Eliminate them with criticism (& guess more) until you've got one left standing.
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So where do we get theories?
We make them up.
We guess 'em. Any will do. Source is irrelevant.
What's important is what you do with guesses afterwards: Try to poke holes in them. Eliminate them with criticism (& guess more) until you've got one left standing.
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EMPIRICISM
Empiricism is the idea that we get knowledge through the senses. Popper's criticism of this is that observation is always theory-laden: we can't make sense of what we're seeing without a theory to interpret it.
Theory comes first. Observations can only refute.
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Empiricism is the idea that we get knowledge through the senses. Popper's criticism of this is that observation is always theory-laden: we can't make sense of what we're seeing without a theory to interpret it.
Theory comes first. Observations can only refute.
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ESSENTIALISM
Essentialism is the idea that things have essences, and you can learn something's true essence by defining it sufficiently precisely.
CR says defining stuff is a words game, a waste of time, circular, and we only need to be as precise as the problem warrants.
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Essentialism is the idea that things have essences, and you can learn something's true essence by defining it sufficiently precisely.
CR says defining stuff is a words game, a waste of time, circular, and we only need to be as precise as the problem warrants.
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RATIONALISM
As opposed to empiricism. That is: we get theories from within our brains, not 'from without' aka sense data.
Unlike other rationalisms, in sense data IS used, but only to:
1. provide us phenomena to explain (EXPLICANDA)
2. whittle down our theories (REFUTATION)
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As opposed to empiricism. That is: we get theories from within our brains, not 'from without' aka sense data.
Unlike other rationalisms, in sense data IS used, but only to:
1. provide us phenomena to explain (EXPLICANDA)
2. whittle down our theories (REFUTATION)
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RATIONALITY
Long story — see this thread:
19/ https://twitter.com/reasonisfun/status/1261310305126277127
Long story — see this thread:
19/ https://twitter.com/reasonisfun/status/1261310305126277127
FALLIBILISM
Typically, people either say that there is objective knowledge and we can know it with varying confidence (Bayesians), or that it's not possible to know anything (relativists).
Fallibilism is the idea we can improve our ideas, yet never know their truth value.
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Typically, people either say that there is objective knowledge and we can know it with varying confidence (Bayesians), or that it's not possible to know anything (relativists).
Fallibilism is the idea we can improve our ideas, yet never know their truth value.
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PROBLEM
A conflict between theories.
Problems are the best thing in the world. Without them, we couldn't think: all thinking is trying to resolve conflicts between ideas. All progress comes from solving problems.
"All life is problem-solving" — Popper
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A conflict between theories.
Problems are the best thing in the world. Without them, we couldn't think: all thinking is trying to resolve conflicts between ideas. All progress comes from solving problems.
"All life is problem-solving" — Popper
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TRADITION
Critical rationalism heavily emphasises *existing knowledge* as the starting point.
Science started when Thales invented the tradition of criticising one's teachers.
CR warns against throwing the baby out with the bathwater. It's anti-utopian, pro-gradualism.
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Critical rationalism heavily emphasises *existing knowledge* as the starting point.
Science started when Thales invented the tradition of criticising one's teachers.
CR warns against throwing the baby out with the bathwater. It's anti-utopian, pro-gradualism.
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