Lulie Tanett vs Critical Rationalism

Lulie Tanett is posting false ideas about critical rationalism. In this tweet, she shows a set of slides about critical rationalism she posted on Instagram: they all include serious errors. I’m going to discuss problems with the slides, point out that her actions are not compatible with taking critical rationalism seriously as a guide to action and that these slides may damage critical rationalism rather than promote it.

First slide:


 ideas must be justified to be knowledge

The core part of the classical view of knowledge which Karl Popper criticised.

“How do we know our ideas are really true?” Classical theory of knowledge

“How do we correct errors?” Karl Popper (Paraphrase)

Compare to: critical rationalism

This attempt at a summary raises many questions that it doesn’t answer and is also misleading. Justificationism is the standard way of understanding epistemology, but this slide doesn’t explain the alternative and why you can do without justification. A list of references to explanations of these issues can be found at the Fallible Ideas books page.

Second slide:

justified true belief

Knowledge is belief that is true and justified.


Justification has an infinite regress.

Saying that justification has an infinite regress is misleading. In reality, there is no explanation of how you could make even a single step in the alleged process of justification. If some fact X is true, then there are many explanations that are compatible with X being true. So X just divides explanations into two classes: explanations incompatible with X and explanations compatible with X. Saying X is true is a criticism of ideas that are incompatible with X, but has no effect on any other ideas. So X can only be used to criticise ideas, not to justify them.

More content from the second slide:

Theories are never perfectly true.

The phrase “theories are never perfectly true” is misleading. Some theories are true: 1+1=2. You can’t justify those ideas, but that has nothing to do with whether they are actually correct.

Also the idea that theories aren’t perfectly true can easily be misunderstood as the idea that there is some way of measuring truth that a theory can partially fulfil to a greater or lesser extent. This is not true. All ideas are either true or false and should be judged as refuted or non-refuted and not given any other status – see yes no philosophy.

An idea may solve some problem despite being false, e.g. Newtonian mechanics. That idea may constitute knowledge, so knowledge doesn’t require truth.

Scientists needn’t believe their theories to make correct predictions.

This is true and it follows from critical rationalism that scientists wouldn’t have to believe ideas to make predictions with them since belief isn’t required for knowledge. Tanett doesn’t explain why this would matter. The reason this is important is that you can consider, discuss or use an idea without believing it. You can be critical of the idea instead and you need not be invested in it. This makes rapid turnover of ideas easier and so makes knowledge creation easier since you can get through ideas that are easy to refute quickly. This is a useful option to have that many people don’t understand.

Additional criticisms: Gettier cases

The Gettier problem is a bad problem and shouldn’t be considered a good account of what’s wrong with justificationism.

Alternative: critical rationalism

Tanett just sez critical rationalism is an alternative but doesn’t explain it, or link to an explanation or give a reference.

Third slide:


All valid ideas must be falsifiable by experimental testing.

A misconceived version of Karl Popper’s philosophy, based on mistaking his *falsifiability criterion* for an entire philosophy.

Tanett doesn’t explain falsification or falsifiability, so anybody who doesn’t know about it already won’t know what the post is about.

Falsifiability is a subtle issue. For example, any observation is itself a guess about what happened in a particular region of space and time. How can we deal with the fact that our observations are conjectures? Also many people don’t understand that observations are conjectures, so lots of people will misunderstand critical rationalism cuz Tanett didn’t bring up this issue. Tanett doesn’t explain it or link or refer to any explanation, such as Chapters 3 and 7 of “The Fabric of Reality” by David Deutsch, Chapters 1 and 2 of “The Beginning of Infinity” by David Deutsch or Chapters 1,2,4 and 5 of “The Logic of Scientific Discovery” by Popper.




Compare to: falsifiability

Falsification occurs when an experiment or observation contradicts a theory and points out that the theory is in error. So falsification is a variety of error correction. So saying “error correction, not falsifiability” is misleading. In addition, a scientific theory can be rejected for reasons other than failing an experimental test, e.g. –  cuz there is no explanation of how it would work. In The Fabric of Reality pp. 5-7, David Deutsch gives the example of rejecting the idea that eating grass cures cancer cuz there is no explanation of how eating grass would cure cancer.

So overall the slides do not contain adequate explanations, nor do they link or refer to adequate explanations. Tanett could have made the readers’ lives a lot easier, but she chose not to. Tanett knows of many people who understand critical rationalism quite well and she could have asked them for feedback on the slides, but she didn’t.

In addition, she posted the slides on Instagram. Instagram is not a forum for intellectual discussion. If you look at how the site is designed on one of Tanett’s posts, there are several problems. The space for discussion is very small compared the the size of the slide. Instagram also doesn’t have threading or decent facilities for quoting. The slides themselves are hard to quote. I had to type out their content again in this post to comment on them. Twitter also has bad threading and facilities for quoting. So none of the platforms Tanett is posting on are optimised for discussion. Both platforms are optimised for social signalling at the expense of intellectual content. The best you can do on either platform is to link or refer to intellectual content, but Tanett doesn’t do that.

Any person who acts like this is playing at being an intellectual and an authority on whatever topic she posts about. She can post about stuff with no mechanism for feedback because she is pretending she knows so much that she needs no feedback. She is also preventing the back and forth discussion required to have several rounds of conjecture and criticism. All of these features of Tanett’s content contradict critical rationalism, which refutes the idea of intellectual authority and sez critical discussion is required for knowledge creation.

Tanett’s actions make CR look like just another source of vapid ‘inspirational’ quotes and she offers no way to correct this impression. If I wanted to corrupt and destroy the CR community I couldn’t do much better than to adopt the tactics that Tanett is following.

There are forums such as the fallible ideas list where Tanett could get criticism of her ideas, but she has chosen not to do so. So Tanett is not correcting her own errors, which is required by critical rationalism.

UPDATE – Some other criticisms were pointed out in a comment by Elliot Temple.

About conjecturesandrefutations
My name is Alan Forrester. I am interested in science and philosophy: especially David Deutsch, Ayn Rand, Karl Popper and William Godwin.

8 Responses to Lulie Tanett vs Critical Rationalism

  1. > Lulie

    Up to you, but I’d refer to her as “Tanett” throughout (or LT). Makes it sound more impersonal. I know her Twitter doesn’t even say her last name so she has granted permission to call her by first name, but I wouldn’t want to accept that offer of fake familiarity (I know you have some actual familiarity, too, but readers don’t know that and I think it’s better to leave that out of the matter).

    >> “How do we know our ideas are really true?” Classical theory of knowledge

    This is wrong. Smaller issue, I don’t like the “really”, I’d delete it. Bigger issue, the problem is how do we know *which* ideas are true, not how do we prove *our* ideas are true. LT has written this in a biased way. Also I think “do” should be “can” – the issue is more about figuring out a working method of learning rather than figuring out what people already do that already accomplishes this goal. We do seem to already do some things that partly work, but an epistemology should also give us some new ideas about what to do rather than purely telling us which things we’re already doing to keep doing and which to stop doing.

    > “If X is true, then Y is true” is a guess and wouldn’t justify Y even if X is true.

    This part is a bit confusing. Like why is it talking about truth instead of justification in the quote at the beginning?

    I think the issue is that X actually divides *all ideas* into two classes. The ones it refutes and the ones it doesn’t refute. Being in the non-refuted category isn’t justification. There is no more specific relationship between X and Y, which isn’t non-contradiction, and somehow means X supports/justifies Y *more than* X supports/justifies every other idea X doesn’t refute. That more specific relationship is a myth. There’s also a common myth that it comes in degrees so then they also have to fudge the problematic issue of the cutoff for how much justification is enough.

    > All ideas are either true or false and should be judged as refuted or non-refuted and no given any other status – see yes no philosophy.

    Typo + what I say to be more precise is no other *epistemological* status. People don’t know what that means, though. Another term could be no other *truth* status. But ideas do have all sorts of other statuses, plenty of which can come in degrees, e.g. amount of trendiness is a status that comes in degrees.

    > An idea may solve some problem despite being false, e.g. – Newtonian mechanics.

    Grammar issue. I think just remove the dash.

    >> Scientists needn’t believe their theories to make correct predictions.

    I think the purpose of that statement is to criticize the “belief” part of JTB. She’s saying it shows something can be knowledge without being belief. Alan’s response in the blog post reads to me like he missed this. (Also: apparently correct predictions are LT’s idea of a good example of knowledge?)

    > Lulie doesn’t explain falsification or falsifiability, so anybody who doesn’t know about it already won’t know what the post is about.

    You have a typo in the slide. The first word is “falsificationism” not “falsifications”

    Yeah. If I were explaining this, I’d specifically point out the slide is for “falsificationism” and then the first line is supposed to explain or define that term, but it doesn’t work because it uses term it’s trying to define (uses “falsifiable”).

    Then, even if you know what it means, “All valid ideas must be falsifiable by experimental testing.” is confusing. What ideas are “valid”? What does “valid” mean? “Valid” is a term from deductive logic but LT isn’t using the technical meaning.

    >> A misconceived version of Karl Popper’s philosophy, based on mistaking his *falsifiability criterion* for an entire philosophy.

    Ugh, I wouldn’t grant it the status of being a “version” of CR.

    > Falsification is pointing out an error, which is required for error correction.

    Falsification in CR terminology often *means*, by definition, empirical falsification. So I would not claim it means “pointing out an error”. This is confusing because people sometimes use or mean “falsification” as any criticism. What I do is use it qualified like “empirical falsification” for clarity, or if I want all criticism then I use another term like “refutation”.

    I think text like “second slide” should link directly to the relevant image on instagram (I’d also advise saving copies of the slides so that you can host the images yourself if LT takes them down)

    LT’s tweet claims “new card daily” but she already missed a day after the 4th one.

    You could mention that she isn’t open to debate *or criticism* about her views on CR, which is contrary to CR.

  2. These supposed flashcards can’t be downloaded and printed. Instagram apparently doesn’t want people to get copies of the images. I ended up screen shotting them to get archived copies. Awful. If they were meant to be educational materials, she’d distribute them in a manner suitable for printing and for copy/pasting text from them.

  3. > they all include serious errors. I’m going to discuss problems with the slides themselves and what they imply about Lulie.

    People reading this will have no idea what’s coming at the end. The “serious errors” is a good preview for the comments on the CR content. But then “what they imply about Lulie” is vague. The ending is quite strong so this kinda intro doesn’t match it well.

  4. Anon says:

    The problem is larger than just Tanett. You should write a similar post about Deutsch. He is behaving like Tanett. And both have not explained why they rejected the FI community.

    • Yes the problem with bad “CR” people, or bad intellectuals, is larger than Tanett. It includes David Miller:

      The CR FB group:

      And, sure, DD:

      And Jordan Peterson, and, more generally, LACK OF PATHS FORWARD (not yelling, no markdown support here):

      Yes, DD and LT choosing not to explain why they left the TCS/FI community is bad. Even if they’d never been involved it’d be bad to dismiss it without sharing any reasoning (no paths forward, inactive/passive/closed mind, no way for error correction to happen). But as major participants it’s much worse.

      DD and LT are very different cases, though. You say “He is behaving like Tanett.” but I disagree.

      DD studied CR a lot, effectively. DD has accomplishments like books that contribute to CR. LT has never studied CR much, never learned that much about it, and has no accomplishments. DD tweets a mix of good and bad tweets, and the bad ones usually aren’t super bad. LT tweets pretty much purely awful tweets. DD is not attempting to attack or undermine FI on purpose or directly, he just ignores it, whereas LT actually is trying to have a negative effect on FI. DD’s tweets are not especially socially manipulative – less than average for an intellectual – but LT’s are extremely socially manipulative. DD’s tweets are also less dishonest than average while LT’s are much more dishonest than average.

      DD, as a philosopher, could be viewed sorta as retired after a productive career (and, yes, retired people are allowed to continue to tweet about their field and do some minor things), whereas LT gave up early on and now is lying about it and trying to build a fake career.

  5. Anon says:

    Yeah, good points about the disimilarities between Deutsch and Tanett. One thing though: Deutsch often retweets bad stuff from Tanett. He is giving her status by doing so. Why is he doing that? Him doing that is having a negative affect on the FI community is it not?

    The intellectual world is in terrible shape isn’t it? Thank you Mr Temple for being a beacon of hope.

    • Elliot Temple says:

      Yes DD is helping LT (and Brett Hall and some others). LT is a personal friend of DD. I think the broader issue is after leaving the TCS/FI people, DD has no one good to talk/interact with (or promote), the options available to him are poor.

      > The intellectual world is in terrible shape isn’t it? Thank you Mr Temple for being a beacon of hope.

      Yes. I hope you’ll get involved in FI discussions more.

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