How Does Veritula Work?

  Dennis Hackethal revised idea #2527. The revision addresses idea #2116.

How Does Veritula Work?

Veritula (Latin for ‘a bit of truth’) can help you live a life guided exclusively by reason.

To reason, within any well-defined epistemology, means to follow and apply that epistemology. Unreason, or whim, is an undue departure from it. Epistemology is the study of knowledge – basically, the study of what helps knowledge grow, what hinders its growth, and related questions.

Veritula follows, and helps you apply, Karl Popper’s epistemology, Critical Rationalism. It’s a continuation of the Athenian tradition of criticism and the only known epistemology without major flaws.1

Critical Rationalism says that ideas are assumed true until refuted. This approach leaves us free to make bold guesses and use the full arsenal at our disposal to criticize these guesses in order to solve problems, correct errors, and seek truth. It’s a creative and critical approach. Critical Rationalism is a fallibilist philosophy: there is no criterion of truth to determine with certainty whether some idea is true or false. We all make mistakes, and by an effort, we can correct them to get a little closer to the truth. Rejecting all forms of mysticism and the supernatural, Veritula recognizes that progress is both possible and desirable, and that rational means are the only way to make progress.

Veritula is a programmatic implementation of Popper’s epistemology.

Veritula provides an objective, partly automated way to tentatively determine whether a given idea is problematic. It does not tell you what to think – it teaches you how to think.

Consider an idea I:

              I

Since it has no criticisms, we tentatively consider I unproblematic. It is rational to adopt it and act in accordance with it. Conversely, it would generally be irrational to reject it, consider it problematic, or act counter to it.

Next, someone submits a criticism C1:

              I
              |
              C1

The idea I is now considered problematic so long as criticism C1 is not addressed. How do you address it? You can revise I so that C1 doesn’t apply anymore, which restores the previous state with just the standalone I (now called I2 to indicate the revision):

                   Revise
              I ------------> I2
              |
              C1

To track changes, Veritula offers beautiful diffing and version control for ideas.

If you cannot think of a way to revise I, you can counter-criticize C1, thereby neutralizing it with a new criticism, C2:

              I
              |
              C1
              |
              C2

Now, I is considered unproblematic again, since C1 is problematic and thus can’t be a decisive criticism anymore.

If you can think of neither a revision of I nor counter-criticism to C1, your only option is to accept that I has been (tentatively) defeated. You should therefore abandon it, which means: stop acting in accordance with it, considering it to be unproblematic, etc.

Since there can be many criticisms (which are also just ideas) and deeply nested counter-criticisms, the result is a tree structure. For example, as a discussion progresses, one of its trees might look like this:

              I
           /  |  \
         C11 C12 C13
         / \       \
       C21 C22     C23
                   / \
                 C31 C32

In this tree, I is considered problematic. Although C11 has been neutralized by C21 and C22, C12 still needs to be addressed. In addition, C23 would have neutralized C13, but C31 and C32 make C23 problematic, so C13 makes I problematic as well.

You don’t need to keep track of these relationships manually. Veritula marks ideas accordingly, automatically.

Because decision-making is a special case of, ie follows the same logic as, truth-seeking, you can use such trees for decision-making, too. Veritula implements unanimous consent as defined by Taking Children Seriously, a parenting philosophy that builds on Popper’s epistemology. When you’re planning your next move but can’t decide on a city, say, Veritula helps you criticize your ideas and make a rational decision – meaning a decision you’ll be happy with. Again, it’s rational to act in accordance with ideas that have no pending criticisms.

All ideas, including criticisms, should be formulated as concisely as possible, and separate ideas should be submitted separately, even if they’re related. Otherwise, you run the risk of receiving ‘bulk’ criticisms, where a single criticism seems to apply to more content than it actually does.

Again, criticisms are also just ideas, so the same is true for criticisms. Submitting each criticism separately has the benefit of requiring the proponent of an idea to address each criticism individually, not in bulk. If he fails to address even a single criticism, the idea remains problematic and should be rejected.

The more you discuss a given topic, the deeper and wider the tree grows. Some criticisms can apply to multiple ideas in the tree, but that needs to be made explicit by submitting them repeatedly.

Comments that aren’t criticisms – eg follow-up questions or otherwise neutral comments – are considered ancillary ideas. Unlike criticisms, ancillary ideas do not invert their respective parents’ statuses. They are neutral.

One of the main benefits of Veritula is that the status of any idea in a discussion can be seen at a glance. If you are new to a much-discussed topic, adopt the displayed status of the ideas involved: if they are marked problematic, reject them; if they are not, adopt them.

Therefore, Veritula acts as a dictionary for ideas.

One of the problems of our age is that people have same discussions over and over again. Part of the reason is widespread irrationality, expressed in the unwillingness to change one’s mind; another is that it’s simply difficult to remember or know what’s true and what isn’t. Discussion trees can get complex, so people shouldn’t blindly trust their judgment of whether some idea is true or problematic, whether nested criticisms have been neutralized or not. Going off of memory is too error prone.

Veritula solves this problem: it makes discussion trees explicit so you don’t have to remember each idea and its relation to other ideas. Veritula therefore also enables you to hold irrational people accountable: if an idea has pending criticisms, the rational approach is to either abandon it or to save it by revising it or addressing all pending criticisms.

Many people don’t like to concede an argument. But with Veritula, no concessions are necessary. The site just shows you who’s right.

Using Veritula, we may discover a bit of truth.


  1. Popperian epistemology has some flaws, like verisimilitude, but Veritula doesn’t implement those.

How Does Veritula Work?

Veritula (Latin for ‘a bit of truth’) can help you live a life guided exclusively by reason.

To reason, within any well-defined epistemology, means to follow and apply that epistemology. Unreason, or whim, is an undue departure from it. Epistemology is the study of knowledge – basically, the study of what helps knowledge grow, what hinders its growth, and related questions.

Veritula follows, and helps you apply, Karl Popper’s epistemology, Critical Rationalism. It’s a continuation of the Athenian tradition of criticism and the only known epistemology without major flaws.1

Critical Rationalism says that ideas are assumed true until refuted. This approach leaves us free to make bold guesses and use the full arsenal at our disposal to criticize these guesses in order to solve problems, correct errors, and seek truth. It’s a creative and critical approach. Critical Rationalism is a fallibilist philosophy: there is no criterion of truth to determine with certainty whether some idea is true or false. We all make mistakes, and by an effort, we can correct them to get a little closer to the truth. Rejecting all forms of mysticism and the supernatural, Veritula recognizes that progress is both possible and desirable, and that rational means are the only way to make progress.

Veritula is a programmatic implementation of Popper’s epistemology.

Veritula provides an objective, partly automated way to tentatively determine whether a given idea is problematic. It does not tell you what to think – it teaches you how to think.

Consider an idea I:

              I

Since it has no criticisms, we tentatively consider I unproblematic. It is rational to adopt it and act in accordance with it. Conversely, it would be irrational to reject it, consider it problematic, or act counter to it. (See #2281 for more details on rational decision-making.)

Next, someone submits a criticism C1:

              I
              |
              C1

The idea I is now considered problematic so long as criticism C1 is not addressed. How do you address it? You can revise I so that C1 doesn’t apply anymore, which restores the previous state with just the standalone I (now called I2 to indicate the revision):

                   Revise
              I ------------> I2
              |
              C1

To track changes, Veritula offers beautiful diffing and version control for ideas.

If you cannot think of a way to revise I, you can counter-criticize C1, thereby neutralizing it with a new criticism, C2:

              I
              |
              C1
              |
              C2

Now, I is considered unproblematic again, since C1 is problematic and thus can’t be a decisive criticism anymore.

If you can think of neither a revision of I nor counter-criticism to C1, your only option is to accept that I has been (tentatively) defeated. You should therefore abandon it, which means: stop acting in accordance with it, considering it to be unproblematic, etc.

Since there can be many criticisms (which are also just ideas) and deeply nested counter-criticisms, the result is a tree structure. For example, as a discussion progresses, one of its trees might look like this:

              I
           /  |  \
         C11 C12 C13
         / \       \
       C21 C22     C23
                   / \
                 C31 C32

In this tree, I is considered problematic. Although C11 has been neutralized by C21 and C22, C12 still needs to be addressed. In addition, C23 would have neutralized C13, but C31 and C32 make C23 problematic, so C13 makes I problematic as well.

You don’t need to keep track of these relationships manually. Veritula marks ideas accordingly, automatically.

Because decision-making is a special case of, ie follows the same logic as, truth-seeking, you can use such trees for decision-making, too. Veritula implements unanimous consent as defined by Taking Children Seriously, a parenting philosophy that builds on Popper’s epistemology. When you’re planning your next move but can’t decide on a city, say, Veritula helps you criticize your ideas and make a rational decision – meaning a decision you’ll be happy with. Again, it’s rational to act in accordance with ideas that have no pending criticisms.

All ideas, including criticisms, should be formulated as concisely as possible, and separate ideas should be submitted separately, even if they’re related. Otherwise, you run the risk of receiving ‘bulk’ criticisms, where a single criticism seems to apply to more content than it actually does.

Again, criticisms are also just ideas, so the same is true for criticisms. Submitting each criticism separately has the benefit of requiring the proponent of an idea to address each criticism individually, not in bulk. If he fails to address even a single criticism, the idea remains problematic and should be rejected.

The more you discuss a given topic, the deeper and wider the tree grows. Some criticisms can apply to multiple ideas in the tree, but that needs to be made explicit by submitting them repeatedly.

Comments that aren’t criticisms – eg follow-up questions or otherwise neutral comments – are considered ancillary ideas. Unlike criticisms, ancillary ideas do not invert their respective parents’ statuses. They are neutral.

One of the main benefits of Veritula is that the status of any idea in a discussion can be seen at a glance. If you are new to a much-discussed topic, adopt the displayed status of the ideas involved: if they are marked problematic, reject them; if they are not, adopt them.

Therefore, Veritula acts as a dictionary for ideas.

One of the problems of our age is that people have same discussions over and over again. Part of the reason is widespread irrationality, expressed in the unwillingness to change one’s mind; another is that it’s simply difficult to remember or know what’s true and what isn’t. Discussion trees can get complex, so people shouldn’t blindly trust their judgment of whether some idea is true or problematic, whether nested criticisms have been neutralized or not. Going off of memory is too error prone.

Veritula solves this problem: it makes discussion trees explicit so you don’t have to remember each idea and its relation to other ideas. Veritula therefore also enables you to hold irrational people accountable: if an idea has pending criticisms, the rational approach is to either abandon it or to save it by revising it or addressing all pending criticisms.

Many people don’t like to concede an argument. But with Veritula, no concessions are necessary. The site just shows you who’s right.

Using Veritula, we may discover a bit of truth.


  1. Popperian epistemology has some flaws, like verisimilitude, but Veritula doesn’t implement those.

  Dennis Hackethal revised idea #2143.

That would be self-coercive.

That would be irrational and self-coercive.

  Dennis Hackethal revised criticism #3025.

How did you conclude that the criticisms aren’t good in the first place? You need counter-criticisms to arrive at that conclusion in the first place.

How did you conclude that the criticisms aren’t good? You need counter-criticisms to arrive at that conclusion in the first place.

  Dennis Hackethal revised criticism #3027.

Say the thought of adopting some idea with no criticisms bothers you. Then you can always try to be the first to suggest criticisms, which will then give you a rational reason not to adopt the idea.

Say the thought of adopting some idea with no criticisms bothers you. Then you can always try to be the first to suggest criticisms, which will then give you a rational reason not to adopt the idea. If instead you fail to come up with criticisms, why not adopt it?

  Dennis Hackethal addressed criticism #2124.

If [an idea] has no pending criticisms, then either 1) no reasons to reject it have been suggested …

If no one has even tried to criticize the idea, its adoption seems premature. (This is a modification of Kieren’s view.)

#2124·Dennis HackethalOP, about 2 months ago

Say the thought of adopting some idea with no criticisms bothers you. Then you can always try to be the first to suggest criticisms, which will then give you a rational reason not to adopt the idea.

  Dennis Hackethal revised criticism #3024.

How did you conclude that the criticisms aren’t good in the first place?

How did you conclude that the criticisms aren’t good in the first place? You need counter-criticisms to arrive at that conclusion in the first place.

  Dennis Hackethal addressed criticism #2122.

What reason could you have to ignore the pending criticisms and adopt it anyway?

Maybe the criticisms aren’t very good.

#2122·Dennis HackethalOP, about 2 months ago

How did you conclude that the criticisms aren’t good in the first place?

  Dennis Hackethal addressed criticism #3022.

What counts as ‘addressing’ a criticism? If I write ‘nuh-uh’ as a counter-criticism, does that neutralize the original?

#3022·Dennis HackethalOP, 10 days ago

Only temporarily at best, since ‘nuh-uh’ would be criticized for lacking substance right away.

  Dennis Hackethal criticized idea #2281.

Rational Decision-Making

Expanding on #2112

If an idea, as written, has no pending criticisms, it’s rational to adopt it and irrational to reject it. What reason could you have to reject it? If it has no pending criticisms, then either 1) no reasons to reject it (ie, criticisms) have been suggested or 2) all suggested reasons have been addressed already.

If an idea, as written, does have pending criticisms, it’s irrational to adopt it and rational to reject it – by reference to those criticisms. What reason could you have to ignore the pending criticisms and adopt it anyway?

#2281·Dennis HackethalOP revised about 1 month ago

What counts as ‘addressing’ a criticism? If I write ‘nuh-uh’ as a counter-criticism, does that neutralize the original?

  Dennis Hackethal revised criticism #2239.

Pasting #2079 here as it’s since been hidden in a resolved child thread and should have applied directly to #2074 in the first place.


My current view is that the only meaningful dichotomy is good vs. bad.

You say yourself in #2071 that one should “always avoid positive arguments.” Calling a theory “good” would be a positive argument.

As I say in #2065, Popperian epistemology has no room for ‘good’ or any other justification. I’m not aware that anyone has successfully proposed a way to measure the ‘hard-to-varyiness’ of theories anyway. We can criticize theories for being arbitrary (which is another word for ‘easy to vary’). That’d be fine. But Popper wouldn’t give them points for not being arbitrary. And arbitrariness isn’t the only type of criticism a theory might receive anyway.

If we follow Popper and get rid of justification, we can’t use ‘good vs bad’ because we can’t use ‘good’. The only dichotomy left standing is ‘has some bad’ vs ‘has no bad’. Another word for ‘pointing out some bad’ is ‘criticism’. So this dichotomy can be rephrased as: ‘has pending criticisms’ vs ‘has no pending criticisms’, or ‘has reasons to be rejected’ vs ‘has no reasons to be rejected’. Note that there’s a difference: if you think some idea is bad, you submit a criticism. If you think it’s good, you can still submit a criticism because it might not yet be as good as you want it to be. So regardless of how good a theory might be, it can still have pending criticisms, and thus reasons to reject it. Think of Newtonian physics, which (I’m told) is a superb theory, but it’s false and (as I understand it) has plenty of pending criticisms.

‘Has pending criticisms’ vs ‘has no pending criticisms’ is directly comparable whereas ‘good’ and ‘bad’ aren’t directly comparable. And ‘has n pending criticisms’ vs ‘has m’ or ‘has 0 pending criticisms’ are even numerically comparable.

Veritula does not implement Deutsch’s epistemology. It implements Popper’s. I don’t think they’re compatible.

(As an aside, I’m not sure how I could implement Deutsch’s epistemology even if I wanted to. Would I give each idea a slider where people can say how ‘good’ the idea is? What values would I give the slider? Would the worst value be -1,000 and the best +1,000? How would users know to assign 500 vs 550? Would a ‘weak’ criticism get a score of 500 and a ‘strong’ one 1,000? What if tomorrow somebody finds an even ‘stronger’ one, does that mean I’d need to extend the slider beyond 1,000? Do I include arbitrary decimal/real numbers? Is an idea’s score reduced by the sum of its criticisms’ scores? If an idea has score 0, what does that mean – undecided? If it has -500, does that mean I should reject it ‘more strongly’ than if it had only -100? And so on. Deutsch says you haven’t understood something if you can’t program it, and I don’t think he could program his epistemology.)

Pasting #2079 here as it’s since been hidden in a resolved child thread and should have applied directly to #2074 in the first place.


My current view is that the only meaningful dichotomy is good vs. bad.

You say yourself in #2071 that one should “always avoid positive arguments.” Calling a theory “good” would be a positive argument.

As I say in #2065, Popperian epistemology has no room for ‘good’ or any other justification. I’m not aware that anyone has successfully proposed a way to measure the ‘hard-to-varyiness’ of theories anyway. We can criticize theories for being arbitrary (which is another word for ‘easy to vary’). That’d be fine. But Popper wouldn’t give them points for not being arbitrary. And arbitrariness isn’t the only type of criticism a theory might receive anyway.

If we follow Popper and get rid of justification, we can’t use ‘good vs bad’ because we can’t use ‘good’. The only dichotomy left standing is ‘has some bad’ vs ‘has no bad’. Another word for ‘pointing out some bad’ is ‘criticism’. So this dichotomy can be rephrased as: ‘has pending criticisms’ vs ‘has no pending criticisms’, or ‘has reasons to be rejected’ vs ‘has no reasons to be rejected’. Note that there’s a difference: if you think some idea is bad, you submit a criticism. If you think it’s good, you can still submit a criticism because it might not yet be as good as you want it to be. So regardless of how good a theory might be, it can still have pending criticisms, and thus reasons to reject it. Think of Newtonian physics, which (I’m told) is a superb theory, but it’s false and (as I understand it) has plenty of pending criticisms.

‘Has pending criticisms’ vs ‘has no pending criticisms’ is directly comparable whereas ‘good’ and ‘bad’ aren’t directly comparable. And ‘has n pending criticisms’ vs ‘has m’ or ‘has 0 pending criticisms’ are even numerically comparable.

Veritula does not implement Deutsch’s epistemology of good vs bad explanations. It implements Popper’s epistemology and TCS’s notion of unanimous consent.

(As an aside, I’m not sure how I could implement Deutsch’s epistemology even if I wanted to. Would I give each idea a slider where people can say how ‘good’ the idea is? What values would I give the slider? Would the worst value be -1,000 and the best +1,000? How would users know to assign 500 vs 550? Would a ‘weak’ criticism get a score of 500 and a ‘strong’ one 1,000? What if tomorrow somebody finds an even ‘stronger’ one, does that mean I’d need to extend the slider beyond 1,000? Do I include arbitrary decimal/real numbers? Is an idea’s score reduced by the sum of its criticisms’ scores? If an idea has score 0, what does that mean – undecided? If it has -500, does that mean I should reject it ‘more strongly’ than if it had only -100? And so on. Deutsch says you haven’t understood something if you can’t program it, and I don’t think he could program his epistemology.)

  Dennis Hackethal submitted idea #3013.

A Society Guided by Reason

The same logic explained in #2281 and #2844 applies to ideas across people as well. A free market or free society, by definition, is one where all interactions are based on unanimous consent.

One difference between the market and individuals is freedom of association. For example, when people disagree, they can just go their separate ways. But a single man cannot do that when parts of him disagree; a single man cannot dissociate from himself.

This difference does not change the overall desirability of unanimous consent both within and across minds. It’s an ‘implementation detail’.

  Dennis Hackethal submitted idea #2844.

A Life Guided by Reason

In #2281, I explain how Veritula helps you make rational decisions – in other words, how to live rationally, ie, a life guided by reason. (I use the words ‘reason’ and ‘rationality’ synonymously. The same goes for ‘unreason’ and ‘irrationality’.)

A life guided by reason defies the dominant, Kantian philosophy of our age. Ayn Rand summarized that philosophy as, “Be rational, except when you don’t feel like it.”1 In other words, it says to mix reason and unreason; to stray from rationality arbitrarily; to be rational only sometimes. It claims that there is a necessary clash between reason and emotion. It is an attack on reason, an attempt to do the impossible – and it leads to dissatisfaction with yourself and conflict with others.

If you are rational only sometimes, if you stray from rationality arbitrarily, then you are irrational. There is no third option. This conclusion can be proven easily: if you tried to stray from rationality non-arbitrarily, ie, if you tried to come up with a considered argument for straying from rationality, you could only do so by following the steps in #2281. And those steps are the application of rationality again.

So it’s impossible to stray from rationality rationally. There is no gray area between reason and unreason. Rationality has an all-or-nothing character. This does not mean that reason has to snuff out all emotion. On the contrary: there is no necessary clash between rationality on the one hand and emotion on the other. Rationality means finding unanimous consent between emotion, explicit thought, inexplicit thought, and any other kind of idea.

If you follow the steps in #2281 consistently, then you are always rational. A life worth living is one guided exclusively by reason. Consistent application of rationality may be difficult at first, but with practice, it will get easier. Master it, and you will have a fighting chance of becoming what David Deutsch calls a beginning of infinity.


  1. Ayn Rand. Philosophy: Who Needs It. ‘From the Horse’s Mouth’ (p. 110). 1975. Kindle Edition. As quoted previously.

  Dennis Hackethal criticized idea #2564.

Thank you for sharing this. I missed this in my read of BoI, and I agree now that Deutsch is wrong on this point.

Separate from Deutsch and going forward with our own epistemological practices, I think it would be appropriate for us to use terms like ‘good’ and ‘hard to vary’ in the sense of ‘not bad’ and ‘not easy to vary’. This eliminates the problem of gradation and positive argument, while preserving a shared and otherwise useful set of terminology.

#2564·Benjamin Davies, about 1 month ago

… us[ing] terms like ‘good’ and ‘hard to vary’ in the sense of ‘not bad’ and ‘not easy to vary’ … eliminates the problem of gradation and positive argument, while preserving a shared and otherwise useful set of terminology.

Remembering and using the new meaning would take practice and effort. Why not just go with ‘has pending criticisms’ and ‘has no pending criticisms’ (or ‘problematic’ and ‘unproblematic’ for short)?

  Dennis Hackethal criticized idea #2564.

Thank you for sharing this. I missed this in my read of BoI, and I agree now that Deutsch is wrong on this point.

Separate from Deutsch and going forward with our own epistemological practices, I think it would be appropriate for us to use terms like ‘good’ and ‘hard to vary’ in the sense of ‘not bad’ and ‘not easy to vary’. This eliminates the problem of gradation and positive argument, while preserving a shared and otherwise useful set of terminology.

#2564·Benjamin Davies, about 1 month ago

[We should continue] to use terms like ‘good’ and ‘hard to vary’ in the sense of ‘not bad’ and ‘not easy to vary’.

There are risks to changing the meaning of established, recognized terms. It could confuse newcomers to this forum who are familiar with Deutsch’s terminology.

  Benjamin Davies commented on criticism #2540.

We could try to save Deutsch’s terminology this way, sure. But I don’t think that’s what he means. He sees room for different gradations of ‘good’. For example, from BoI ch. 9:

[W]e should choose between policies not on the basis of their origin, but according to how good they are as explanations: how hard to vary.

#2540·Dennis HackethalOP, about 1 month ago

Thank you for sharing this. I missed this in my read of BoI, and I agree now that Deutsch is wrong on this point.

Separate from Deutsch and going forward with our own epistemological practices, I think it would be appropriate for us to use terms like ‘good’ and ‘hard to vary’ in the sense of ‘not bad’ and ‘not easy to vary’. This eliminates the problem of gradation and positive argument, while preserving a shared and otherwise useful set of terminology.

  Benjamin Davies revised criticism #2533. The revision addresses idea #2541.

Removed focus on ‘good vs bad’ as a particularly important dichotomy


If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper? (Using Edwin’s conception of good and bad.)

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

If “good” is considered the same as “not bad” (or the equivalent in any epistemological dichotomy) doesn’t that close the gap between Deutsch and Popper?

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

  Benjamin Davies addressed criticism #2560.

I meant this conception from #2073:

My current view is that the only meaningful dichotomy is good vs. bad

If we take ‘good vs bad’ to be the only meaningful dichotomy, and if we state that ‘good’ is the equivalent of ‘not bad’, I think that bridges Popper and Deutsch.

#2560·Benjamin Davies, about 1 month ago

We don’t need to take ‘good vs bad’ to be the only meaningful dichotomy for the idea to stand, so Edwin’s idea is not important to the argument.

  Benjamin Davies addressed criticism #2541.

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper? (Using Edwin’s conception of good and bad.)

Do you have a quote of Edwin saying good = not bad?

#2541·Dennis HackethalOP, about 1 month ago

I meant this conception from #2073:

My current view is that the only meaningful dichotomy is good vs. bad

If we take ‘good vs bad’ to be the only meaningful dichotomy, and if we state that ‘good’ is the equivalent of ‘not bad’, I think that bridges Popper and Deutsch.

  Dennis Hackethal criticized idea #2109.

@dennis-hackethal you have regularly pointed out to me that it’s a mistake to assign strengths or weaknesses to arguments—for example, in #1809 and #1927. I’d love to get to the bottom of that.

On one hand, I see what you mean. A criticism can either be counter-criticized or it can be an unresolved error. If it’s a bad criticism, you quickly counter it—say, by clarifying why it’s irrelevant—and move on.

I also see why talking about a “gradient” or comparative strength between arguments is problematic: there’s no objective criterion to measure them against. We can only say one theory is better than another when both attempt to explain the same phenomenon—then we can evaluate them using properties such as hard-to-varyness and other criteria Deutsch describes. (We can get into that if you’d like, though I don’t think that’s our main disagreement.). But this comparison doesn’t apply when we’re dealing with very different criticisms of a single idea, because there’s no common standard to measure them against. Comparing their “strength” becomes arbitrary.

However, I still think there are good and bad criticisms, just as there are good and bad explanations (following Deutsch’s distinction: for instance, bad explanations are easy to vary or point to authorities to justify themselves rather than offering a hard-to-vary account of how and why something works). While I could simply counter-criticize bad criticisms and move on, there’s also the matter of efficiency and opportunity cost: I don’t want to waste time repeatedly countering poor criticisms, or worse, get stuck in circular debates with people who don’t recognize that some arguments aren’t good criticisms at all. I’d rather focus my attention on good criticisms.

To clarify what I mean, here’s an excerpt from my book:

The most important principle to remember while criticizing is: Criticize, don’t defend or attack. Good explanations invite criticism of their intrinsic content—whether the explanation itself works, solves the problem, and avoids worse side effects. Bad explanations, by contrast, deflect criticism onto irrelevant, extrinsic properties such as authority or track record—e.g., “this is the method that successful company X uses,” “I believe strongly in this approach,” or “it’s coming from person Y, so it’s worthless.”

That kind of “criticism” isn’t real criticism at all. It’s just attacking or defending. And when we play that game, the explanation itself stays untouched and stagnant. The idea doesn’t get scrutinized or improved—it only gets shielded or dismissed for irrelevant reasons.

That being said, I agree with the points you brought up in #2061, namely that there can be no positive arguments for an idea. By extension, if Veritula would require a specific format or mode of criticism, we’d fall into the very error Popper warns about with the Myth of the Framework—the mistaken belief that criticism requires a shared framework or language. So, Veritula should functionally remain as it is. At most, you might consider adding guidelines on what constitutes good versus poor criticism, so that critics can improve their skills. But I agree: the person who created the idea should remain solely responsible for addressing the criticisms they receive, not dismissing them as “bad” and moving on.

Tagging @bart-vanderhaegen because he and I have discussed this at length—in fact, I got the defending/attacking framing from him.

#2109·Edwin de Wit revised about 2 months ago

… I still think there are good and bad criticisms …

To conclude that a criticism is bad, we first need counter-criticisms. Otherwise, we have no reasons for considering a criticism bad. And once we have those reasons in the form of counter-criticisms, we can just state them.

  Dennis Hackethal addressed criticism #2533.

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper? (Using Edwin’s conception of good and bad.)

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

#2533·Benjamin Davies revised about 1 month ago

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper? (Using Edwin’s conception of good and bad.)

Do you have a quote of Edwin saying good = not bad?

  Dennis Hackethal addressed criticism #2533.

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper? (Using Edwin’s conception of good and bad.)

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

#2533·Benjamin Davies revised about 1 month ago

We could try to save Deutsch’s terminology this way, sure. But I don’t think that’s what he means. He sees room for different gradations of ‘good’. For example, from BoI ch. 9:

[W]e should choose between policies not on the basis of their origin, but according to how good they are as explanations: how hard to vary.

  Benjamin Davies revised criticism #2531.

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper?

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper? (Using Edwin’s conception of good and bad.)

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

  Benjamin Davies revised criticism #2530.

Added “easy to vary” example


If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper?

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper?

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

Similarly, “hard to vary” would just be an equivalent of “not easy to vary”.

  Benjamin Davies addressed criticism #2239.

Pasting #2079 here as it’s since been hidden in a resolved child thread and should have applied directly to #2074 in the first place.


My current view is that the only meaningful dichotomy is good vs. bad.

You say yourself in #2071 that one should “always avoid positive arguments.” Calling a theory “good” would be a positive argument.

As I say in #2065, Popperian epistemology has no room for ‘good’ or any other justification. I’m not aware that anyone has successfully proposed a way to measure the ‘hard-to-varyiness’ of theories anyway. We can criticize theories for being arbitrary (which is another word for ‘easy to vary’). That’d be fine. But Popper wouldn’t give them points for not being arbitrary. And arbitrariness isn’t the only type of criticism a theory might receive anyway.

If we follow Popper and get rid of justification, we can’t use ‘good vs bad’ because we can’t use ‘good’. The only dichotomy left standing is ‘has some bad’ vs ‘has no bad’. Another word for ‘pointing out some bad’ is ‘criticism’. So this dichotomy can be rephrased as: ‘has pending criticisms’ vs ‘has no pending criticisms’, or ‘has reasons to be rejected’ vs ‘has no reasons to be rejected’. Note that there’s a difference: if you think some idea is bad, you submit a criticism. If you think it’s good, you can still submit a criticism because it might not yet be as good as you want it to be. So regardless of how good a theory might be, it can still have pending criticisms, and thus reasons to reject it. Think of Newtonian physics, which (I’m told) is a superb theory, but it’s false and (as I understand it) has plenty of pending criticisms.

‘Has pending criticisms’ vs ‘has no pending criticisms’ is directly comparable whereas ‘good’ and ‘bad’ aren’t directly comparable. And ‘has n pending criticisms’ vs ‘has m’ or ‘has 0 pending criticisms’ are even numerically comparable.

Veritula does not implement Deutsch’s epistemology. It implements Popper’s. I don’t think they’re compatible.

(As an aside, I’m not sure how I could implement Deutsch’s epistemology even if I wanted to. Would I give each idea a slider where people can say how ‘good’ the idea is? What values would I give the slider? Would the worst value be -1,000 and the best +1,000? How would users know to assign 500 vs 550? Would a ‘weak’ criticism get a score of 500 and a ‘strong’ one 1,000? What if tomorrow somebody finds an even ‘stronger’ one, does that mean I’d need to extend the slider beyond 1,000? Do I include arbitrary decimal/real numbers? Is an idea’s score reduced by the sum of its criticisms’ scores? If an idea has score 0, what does that mean – undecided? If it has -500, does that mean I should reject it ‘more strongly’ than if it had only -100? And so on. Deutsch says you haven’t understood something if you can’t program it, and I don’t think he could program his epistemology.)

#2239·Dennis HackethalOP revised about 2 months ago

If “good” is considered the same as “not bad” doesn’t that close the gap between Deutsch and Popper?

If “bad” = “contains known flaws”,
and “not bad” = “contains no known flaws”,
why can’t “good” = “contains no known flaws” too?

I can see no reason that “good” means anything more than “not bad”.

  Dennis Hackethal revised idea #2433.

Improve language and credit TCS


How Does Veritula Work?

Veritula (Latin for ‘a bit of truth’) can help you live a life guided exclusively by reason.

To reason, within any well-defined epistemology, means to follow and apply that epistemology. Unreason, or whim, is an undue departure from it. Epistemology is the study of knowledge – basically, the study of what helps knowledge grow, what hinders its growth, and related questions.

Veritula follows, and helps you apply, Karl Popper’s epistemology, Critical Rationalism. It’s a continuation of the Athenian tradition of criticism and the only known epistemology without major flaws.1

Critical Rationalism says that ideas are assumed true until refuted. This approach leaves us free to make bold guesses and use the full arsenal at our disposal to criticize these guesses in order to solve problems, correct errors, and seek truth. It’s a creative and critical approach. Critical Rationalism is a fallibilist philosophy: it states that there is no criterion of truth to determine with certainty whether some idea is true or false. We all make mistakes, and by an effort, we can correct them to get a little closer to the truth. Rejecting all forms of mysticism and the supernatural, Veritula recognizes that progress is both possible and desirable, and that rational means are the only way to make progress.

Veritula is a programmatic implementation of Popper’s epistemology.

Veritula provides an objective, partly automated way to tentatively determine whether a given idea is problematic. It does not tell you what to think – it teaches you how to think.

Consider an idea I:

              I

Since it has no criticisms, we tentatively consider I unproblematic. It is rational to adopt it and act in accordance with it. Conversely, it would generally be irrational to reject it, consider it problematic, or act counter to it.

Next, someone submits a criticism C1:

              I
              |
              C1

The idea I is now considered problematic so long as criticism C1 is not addressed. How do you address it? You can revise I so that C1 doesn’t apply anymore, which restores the previous state with just the standalone I (now called I2 to indicate the revision):

                   Revise
              I ------------> I2
              |
              C1

To track changes, Veritula offers beautiful diffing and version control for ideas.

If you cannot think of a way to revise I, you can counter-criticize C1, thereby neutralizing it with a new criticism, C2:

              I
              |
              C1
              |
              C2

Now, I is considered unproblematic again, since C1 is problematic and thus can’t be a decisive criticism anymore.

If you can think of neither a revision of I nor counter-criticism to C1, your only option is to accept that I has been (tentatively) defeated. You should therefore abandon it, which means: stop acting in accordance with it, considering it to be unproblematic, etc.

Since there can be many criticisms (which are also just ideas) and deeply nested counter-criticisms, the result is a tree structure. For example, as a discussion progresses, one of its trees might look like this:

              I
           /  |  \
         C11 C12 C13
         / \       \
       C21 C22     C23
                   / \
                 C31 C32

In this tree, I is considered problematic. Although C11 has been neutralized by C21 and C22, C12 still needs to be addressed. In addition, C23 would have neutralized C13, but C31 and C32 make C23 problematic, so C13 makes I problematic as well.

You don’t need to keep track of these relationships manually. Veritula marks ideas accordingly, automatically.

Because decision-making is a special case of, ie follows the same logic as, truth-seeking, such trees can be used for decision-making, too. When you’re planning your next move but can’t decide on a city, say, Veritula helps you criticize your ideas and make a rational decision – meaning a decision you’ll be happy with. Again, it’s rational to act in accordance with ideas that have no pending criticisms.

All ideas, including criticisms, should be formulated as concisely as possible, and separate ideas should be submitted separately, even if they’re related. Otherwise, you run the risk of receiving ‘bulk’ criticisms, where a single criticism seems to apply to more content than it actually does.

Again, criticisms are also just ideas, so the same is true for criticisms. Submitting each criticism separately has the benefit of requiring the proponent of an idea to address each criticism individually, not in bulk. If he fails to address even a single criticism, the idea remains problematic and should be rejected.

The more you discuss a given topic, the deeper and wider the tree grows. Some criticisms can apply to multiple ideas in the tree, but that needs to be made explicit by submitting them repeatedly.

Comments that aren’t criticisms – eg follow-up questions or otherwise neutral comments – are considered ancillary ideas. Unlike criticisms, ancillary ideas do not invert their respective parents’ statuses. They are neutral.

One of the main benefits of Veritula is that the status of any idea in a discussion can be seen at a glance. If you are new to a much-discussed topic, adopt the displayed status of the ideas involved: if they are marked problematic, reject them; if they are not, adopt them.

Therefore, Veritula acts as a dictionary for ideas.

One of the problems of our age is that people have same discussions over and over again. Part of the reason is widespread irrationality, expressed in the unwillingness to change one’s mind; another is that it’s simply difficult to remember or know what’s true and what isn’t. Discussion trees can get complex, so people shouldn’t blindly trust their judgment of whether some idea is true or problematic, whether nested criticisms have been neutralized or not. Going off of memory is too error prone.

Veritula solves this problem: it makes discussion trees explicit so you don’t have to remember each idea and its relation to other ideas. Veritula therefore also enables you to hold irrational people accountable: if an idea has pending criticisms, the rational approach is to either abandon it or to save it by revising it or addressing all pending criticisms.

Many people don’t like to concede an argument. But with Veritula, no concessions are necessary. The site just shows you who’s right.

Using Veritula, we may discover a bit of truth.


  1. Popperian epistemology has some flaws, like verisimilitude, but Veritula doesn’t implement those.

How Does Veritula Work?

Veritula (Latin for ‘a bit of truth’) can help you live a life guided exclusively by reason.

To reason, within any well-defined epistemology, means to follow and apply that epistemology. Unreason, or whim, is an undue departure from it. Epistemology is the study of knowledge – basically, the study of what helps knowledge grow, what hinders its growth, and related questions.

Veritula follows, and helps you apply, Karl Popper’s epistemology, Critical Rationalism. It’s a continuation of the Athenian tradition of criticism and the only known epistemology without major flaws.1

Critical Rationalism says that ideas are assumed true until refuted. This approach leaves us free to make bold guesses and use the full arsenal at our disposal to criticize these guesses in order to solve problems, correct errors, and seek truth. It’s a creative and critical approach. Critical Rationalism is a fallibilist philosophy: there is no criterion of truth to determine with certainty whether some idea is true or false. We all make mistakes, and by an effort, we can correct them to get a little closer to the truth. Rejecting all forms of mysticism and the supernatural, Veritula recognizes that progress is both possible and desirable, and that rational means are the only way to make progress.

Veritula is a programmatic implementation of Popper’s epistemology.

Veritula provides an objective, partly automated way to tentatively determine whether a given idea is problematic. It does not tell you what to think – it teaches you how to think.

Consider an idea I:

              I

Since it has no criticisms, we tentatively consider I unproblematic. It is rational to adopt it and act in accordance with it. Conversely, it would generally be irrational to reject it, consider it problematic, or act counter to it.

Next, someone submits a criticism C1:

              I
              |
              C1

The idea I is now considered problematic so long as criticism C1 is not addressed. How do you address it? You can revise I so that C1 doesn’t apply anymore, which restores the previous state with just the standalone I (now called I2 to indicate the revision):

                   Revise
              I ------------> I2
              |
              C1

To track changes, Veritula offers beautiful diffing and version control for ideas.

If you cannot think of a way to revise I, you can counter-criticize C1, thereby neutralizing it with a new criticism, C2:

              I
              |
              C1
              |
              C2

Now, I is considered unproblematic again, since C1 is problematic and thus can’t be a decisive criticism anymore.

If you can think of neither a revision of I nor counter-criticism to C1, your only option is to accept that I has been (tentatively) defeated. You should therefore abandon it, which means: stop acting in accordance with it, considering it to be unproblematic, etc.

Since there can be many criticisms (which are also just ideas) and deeply nested counter-criticisms, the result is a tree structure. For example, as a discussion progresses, one of its trees might look like this:

              I
           /  |  \
         C11 C12 C13
         / \       \
       C21 C22     C23
                   / \
                 C31 C32

In this tree, I is considered problematic. Although C11 has been neutralized by C21 and C22, C12 still needs to be addressed. In addition, C23 would have neutralized C13, but C31 and C32 make C23 problematic, so C13 makes I problematic as well.

You don’t need to keep track of these relationships manually. Veritula marks ideas accordingly, automatically.

Because decision-making is a special case of, ie follows the same logic as, truth-seeking, you can use such trees for decision-making, too. Veritula implements unanimous consent as defined by Taking Children Seriously, a parenting philosophy that builds on Popper’s epistemology. When you’re planning your next move but can’t decide on a city, say, Veritula helps you criticize your ideas and make a rational decision – meaning a decision you’ll be happy with. Again, it’s rational to act in accordance with ideas that have no pending criticisms.

All ideas, including criticisms, should be formulated as concisely as possible, and separate ideas should be submitted separately, even if they’re related. Otherwise, you run the risk of receiving ‘bulk’ criticisms, where a single criticism seems to apply to more content than it actually does.

Again, criticisms are also just ideas, so the same is true for criticisms. Submitting each criticism separately has the benefit of requiring the proponent of an idea to address each criticism individually, not in bulk. If he fails to address even a single criticism, the idea remains problematic and should be rejected.

The more you discuss a given topic, the deeper and wider the tree grows. Some criticisms can apply to multiple ideas in the tree, but that needs to be made explicit by submitting them repeatedly.

Comments that aren’t criticisms – eg follow-up questions or otherwise neutral comments – are considered ancillary ideas. Unlike criticisms, ancillary ideas do not invert their respective parents’ statuses. They are neutral.

One of the main benefits of Veritula is that the status of any idea in a discussion can be seen at a glance. If you are new to a much-discussed topic, adopt the displayed status of the ideas involved: if they are marked problematic, reject them; if they are not, adopt them.

Therefore, Veritula acts as a dictionary for ideas.

One of the problems of our age is that people have same discussions over and over again. Part of the reason is widespread irrationality, expressed in the unwillingness to change one’s mind; another is that it’s simply difficult to remember or know what’s true and what isn’t. Discussion trees can get complex, so people shouldn’t blindly trust their judgment of whether some idea is true or problematic, whether nested criticisms have been neutralized or not. Going off of memory is too error prone.

Veritula solves this problem: it makes discussion trees explicit so you don’t have to remember each idea and its relation to other ideas. Veritula therefore also enables you to hold irrational people accountable: if an idea has pending criticisms, the rational approach is to either abandon it or to save it by revising it or addressing all pending criticisms.

Many people don’t like to concede an argument. But with Veritula, no concessions are necessary. The site just shows you who’s right.

Using Veritula, we may discover a bit of truth.


  1. Popperian epistemology has some flaws, like verisimilitude, but Veritula doesn’t implement those.