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A three-page paper that shook philosophy, with lessons for software engineers

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Re: A three-page paper that shook philosophy, with lessons for software engineers

#171

Post by karmakaze »

So just to be clear, a 'gettier' is when something you Believe and have Justification for turns out to be false?

  Actually True
  J B
  1 1 knowing
  1 0 denying
  0 1 lucky hunch
  0 0 sceptic, default position

  Actually False
  J B
  1 1 mis-justification: un/incorrectly-verified 
  1 0 lucky denial of mis-justified
  0 1 superstition
  0 0 sceptic, default position

Re: A three-page paper that shook philosophy, with lessons for software engineers

#172

Post by mlthoughts2018 »

empath75 wrote: post #78
mlthoughts2018 wrote: post #49

I actually disagree with the Gettier thought experiment and don’t believe it demonstrates anything interesting. When you see the cow (but it’s really a convincing model), then in your mind, there should be some probability assigned to a variety of outcomes. The main one would be a cow, another one might be that you’re hallucinating, and so on down the list, and somewhere the outcome of cow-like model would be there.…

> From that point you can go in at least two directions, one would be something like a Turing test of the fake cow... beyond a certain point it’s a matter of semantics as to whether it’s a real cow or not, or you could say that your “justified true belief” had to apply to the total state of the field. If you believed there was both a cow model and a cow behind it, that woukd be justified, but the existence of the cow…

I’m saying the model it would like to criticize is not an interesting or worthwhile model to talk much about.

Re: A three-page paper that shook philosophy, with lessons for software engineers

#173

Post by throwawayjava »

mdorazio wrote: post #119
bunderbunder wrote: post #85

> A philosopher might say that these aren’t bona fide Gettier cases. True gettiers are rare. But it’s still a useful idea... At least as presented, I see the idea being used to do more harm than good. Take the first example, with the form not autofocusing. We're already not in a Gettier case, because the author didn't have JTB. The belief that he caused the bug obviously wasn't true. But it wasn't justified, either.…

How is it not a JTB? Belief: The pull request broke the search field auto focus. Truth: The pull request did break it. There was an additional reason beyond the pull request unknown to the author, but that's not important to the Truth portion here. Justified: This is the only one you can really debate on, just as philosophers have for a long time. Was he justified in his belief that he broke autofocus? I think so bas…

Typically, philosophers would not consider a belief about a formal system justified unless that belief is backed by a proof.

In software, for known behavioral specs, you don't have a real justification until you write a formal proof. Just because formal proofs are uneconomical doesn't mean there's some fundamental philosophical barrier preventing you from verifying your UI code. Doing so is not just possible, there are even tools for doing it.

So really, this is not a Gettier case, because in formal systems a true justification is possible to construct in the form of a mathematical proof.

An example of a Gettier case in a software system would be formally verifying something with respect to a model/spec that is a Gettierian correct-but-incorrect model of the actual system.

There are almost no software systems where we have true JTB (proofs), so there are almost none where Gettier cases really apply.

Uncertainty in software is more about the economics of QA than it is about epistemology or Gettier style problems, and that will remain true until we start writing proofs about all our code, which will probably never happen.

Re: A three-page paper that shook philosophy, with lessons for software engineers

#174

Post by dTal »

dTal wrote: post #158
thewarrior wrote: post #15

I think it helps to look at the mind as a probabilistic survival engine than some truth engine. If there appears to be a cow in a random field the odds are extremely low that someone put a papier mache cow there. If there’s something that has 50 % chance of being a snake you panic and run because that’s a 50 % chance of dying. In the case of the authors bug yes the change he introduced had a good probability of being…

This is an excellent comment - I'm just disappointed you managed to say it all without the word "Bayesian". The base rate for paper mache cows in fields is very low - one is perfectly justified in assigning a decent probability that a field contains a cow, if one sees a cow-shaped object in it. If you are in a part of the world that has a lot of cows in fields, you will presumably assign an even higher probability. Y…

I've thought a bit more about it, and concluded that while the above is a neat answer, it doesn't explain the question, and [thewarrior]'s remarks were nearer the mark on that. So here goes.

It's tempting to think of "knowledge" as some relationship between the mind and a single fact. But when we use the word "knowledge", what we actually mean is "an accurate world model" - a set of beliefs. This is the disconnect that Gettier cases are designed to expose - they construct scenarios where someone's mental model is inaccurate or incomplete, yet by sheer luck produce a single, cherry-picked correct prediction. We are uncomfortable calling these correct predictions "knowledge" because as soon as you start probing the rest of the mental model, it falls apart. Sure, they think there's a cow in the field, and there really is one. Ask them any more questions about the scenario though ("what color is the cow?") and they'll give wrong answers.

From this perspective, "knowledge" as a "justified, true belief" is a perfectly coherent concept - the problem lies with the inadequacy of the word "justified" to describe the output of a complex decision procedure that incorporates many beliefs about the world, such that it could be expected to yield many other correct predictions in addition to the one in question, up to some arbitrary threshold.

A thought experiment - suppose you tell the observer that the cow they see is made of paper mache. They no longer believe there is a cow in the field. Intuitively, has their knowledge increased or decreased?

Re: A three-page paper that shook philosophy, with lessons for software engineers

#176

Post by wahern »

simonh wrote: post #114
bunderbunder wrote: post #85

> A philosopher might say that these aren’t bona fide Gettier cases. True gettiers are rare. But it’s still a useful idea... At least as presented, I see the idea being used to do more harm than good. Take the first example, with the form not autofocusing. We're already not in a Gettier case, because the author didn't have JTB. The belief that he caused the bug obviously wasn't true. But it wasn't justified, either.…

Arguably the Gettier example of the cow falls into the same realm. Cows move, eat grass and go 'Moo. Did the observer see it do these things, or just go on the silhouette? Then they were not rigorous enough to have a justified belief. But then we can get back to a better Gettier case if we suppose that Boston Dynamics happens to be testing their new Robo-Cow military infiltration unit in the field at the time.

What if the facsimile does all of those things? My initial reaction to the example was, "so what"? The guy _knew_ there was a cow but was wrong. The fact a _real_ cow existed behind the fascimile is irrelevant. All knowledge is contingent and relative. How could it be otherwise? What if 100% of all cow facsimiles ever displayed in the past were displayed on a farm with real cows--would that alone be sufficient to justify an inference of a cow nearby? To say that a belief is _justified_ simply begs the question--how can you _really_ know the truth of something?

In the scientific method you can never prove hypotheses, you can only disprove them. 'nuff said.

I find the Gettier problem entirely uninteresting myself. Someone elsethread explained it in the context of technical discourse in philosophy, in which case I could maybe appreciate the issue as a way to test and explore epistemological theories in a systematic, rigorous manner, even if for many theories it's not particularly challenging to overcome.

Re: A three-page paper that shook philosophy, with lessons for software engineers

#177

Post by DATACOMMANDER »

bunderbunder wrote: post #85

> A philosopher might say that these aren’t bona fide Gettier cases. True gettiers are rare. But it’s still a useful idea... At least as presented, I see the idea being used to do more harm than good. Take the first example, with the form not autofocusing. We're already not in a Gettier case, because the author didn't have JTB. The belief that he caused the bug obviously wasn't true. But it wasn't justified, either.…

The author did have a JTB that his pull request caused the bug. The point is that we hesitate to say that he knew that his pull request caused the bug, because he had the wrong justification. If you take issue with the justification, suppose that he was supposed to be the only one working on the code that day, and that the person who introduced the bug was working from home without telling anyone. He’d then have a JTB but still lack knowledge. If even that isn’t enough justification for you, then you have a problem with the entire JTB definition, and you’re essentially offering a circular definition as an alternative (since the only justification you’ll accept is justification that itself provides knowledge).

Re: A three-page paper that shook philosophy, with lessons for software engineers

#178

Post by pitermarx »

It might be true that even though I have a JTB about something I might be wrong.

Nevertheless, I think It would be resonable to act upon a JTB as it it was true. For all effects it is true to the best of my knowledge. This does not mean I shun down new information that might make me to change my JTB.

And if having a JTB is not knowledge, what is? What can we know? We can always imagine a world where even our most firm JTB might be false. If a JTB is not a good case to use the word knowledge I don't know what is

Re: A three-page paper that shook philosophy, with lessons for software engineers

#179

Post by andrewf »

chii wrote: post #27
austinjp wrote: post #2

The "cow in the field" example reminds me of two heuristics I like: am I right for the wrong reason?; am I wrong for the right reason? Being right for the wrong reason is dangerous: it's not easy to spot, and it perpetuates false sense of security leaving "black swan events" unanticipated. This might occur during debugging as the article points out, or e.g. during A/B testing of a product. Bring wrong for the right r…

> Bring wrong for the right reason is just plain frustrating. what's an example of being wrong for the right reason? I can't think of any cases where this happens...

My compensation includes company stock. I sell that stock, and some of the proceeds end up in index funds. I do this because I want a diversified portfolio.

My employer's stock is up 28% over the last year, S&P 500 is down 6%.

I guess my goal going in was to reduce variance, so I wasn't "wrong" about anything. 36% more money would be nice, though. (I haven't changed my strategy as a result)

Re: A three-page paper that shook philosophy, with lessons for software engineers

#180

Post by simonh »

wahern wrote: post #176
simonh wrote: post #114

Earlier quoted context omitted.

Arguably the Gettier example of the cow falls into the same realm. Cows move, eat grass and go 'Moo. Did the observer see it do these things, or just go on the silhouette? Then they were not rigorous enough to have a justified belief. But then we can get back to a better Gettier case if we suppose that Boston Dynamics happens to be testing their new Robo-Cow military infiltration unit in the field at the time.

What if the facsimile does all of those things? My initial reaction to the example was, "so what"? The guy _knew_ there was a cow but was wrong. The fact a _real_ cow existed behind the fascimile is irrelevant. All knowledge is contingent and relative. How could it be otherwise? What if 100% of all cow facsimiles ever displayed in the past were displayed on a farm with real cows--would that alone be sufficient to jus…

It's interesting because until Gettier nobody had actually proved that a justified true belief does not constitute what we commonly consider to be knowledge.

It's all very well dismissing it an inconsequential, but several generations of philosophers and scientists have grown up in the post-Gettier world, before which the Justified True Belief account was widely considered to be unassailable. Yes _now_ we all know better and are brought up knowing this, but Gettier and his huge influence on later thought is the reason why and it's just that not many people are aware of this.

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