Gettiers in software engineering (2019)

Physics has kinda-solved what it means to know something.

- JTB is not enough, for something to be “true” it needs _testability_. In other words, make a prediction from your knowledge-under-test which would be novel information (for example, “we’ll find fresh cow dung in the field”). - nothing is really ever considered “true”, there’s only theories that describe reality increasingly correctly

In fact, physics did away with the J: it doesn’t matter that your belief is justified if it’s tested. You could make up a theory with zero justification (which doesn’t contradict existing knowledge ofc), make predictions and if they’re tested, that’s still knowledge. The J is just the way that beliefs are formed (inference)

Why did the physicist stop hanging out with philosophers?

Because every time they said, "I've found the absolute truth," the philosophers just replied, "Only in your frame of reference!"

"Testability" to me sounds like a type of "justified" - I can be justified for many reasons, and testability is just one of those. But there are reasons where I might be justified but where testability is impossible.

For example, if I toss a coin and it comes up heads, put the coin in my pocket and then go about my day, and later on say to somebody "I tossed a coin earlier, and it came up heads", that is a JTB, but it's not testable. You might assume I'm lying, but we're not talking about whether you have a JTB in whether I tossed a heads or not, we're talking about if I have one.

There are many areas of human experience where JTB is about as good as we are going to get, and testability is off-limits. If somebody tells me they saw an alien climb out of a UFO last night, I have lots of reasons to not believe them, but if this a very trustworthy individual who has never lied to me about anything in my decades of experience of knowing them, I might have a JTB that they think this is true, even if it isn't. But none of it is testable.

Physics - the scientific method as a whole - is a superb way to think about and understand huge swathes of the World, but it has mathematically proven limits, and that's fine, but let's not assume that just because something isn't testable it can't be true.

> JTB is not enough, for something to be “true” it needs _testability_

How could something become true in the first place such that it could be tested to discover that it is true, if the test precedes and is a condition for truth?

Do you have tests I can run on each of your many assertions here that prove their truth?

Testability as you describe it seems to give you more than just knowledge, but also some amount of understanding: understanding of consequences (not necessarily understanding of causes) — you mentioned the ability to make predictions about the consequences of actions (e.g. 'tests'). (Aside: it seems that you can say you know something, it's a narrow enough concept to be sharp, while understanding something can only ever be true to a degree: it's broad without limit!)

But you may have conflated 'testability' and 'tested'. Can I know there is a cow in the field if I don't check? Seeing it was already evidence, testing just collects more evidence, so how can that matter? Should we set a certainty threshold on knowledge? Could be reasonable.

Maybe prediction-making is too strong to be necessary for 'knowing', if we allow knowing some fact in a domain of knowledge of which you're otherwise clueless. Although very reasonable to not call this knowledge. Suppose I learn of an mathematical theorem in a field that's so unfamiliar that I can't collect evidence to independently gain confidence in it.