Gettiers in software engineering (2019)

"All swans are white."

This statement cannot be proven because it's not possible to observe all swans. There may be some swan in some hidden corner of the earth (or universe) that I did not see.

If I see one black swan, I have falsified that statement.

When you refer to "Not all swans are white" This statement can be proven true but why? This is because the original statement is a universal claim and the negation is a particular claim.

The key distinction between universal claims and particular claims explains why you can "prove" the statement "Not all swans are white." Universal claims, like "All swans are white," attempt to generalize about all instances of a phenomenon. These kinds of statements can never be definitively proven true because they rely on inductive reasoning—no matter how many white swans are observed, there’s always the possibility that a counterexample (a non-white swan) will eventually be found.

In contrast, particular claims are much more specific. The statement "Not all swans are white" is a particular claim because it is based on falsification—it only takes the observation of one black swan to disprove the universal claim "All swans are white." Since black swans have been observed, we can confidently say "Not all swans are white" is true.

Popper's philosophy focuses on how universal claims can never be fully verified (proven true) through evidence, because future observations could always contradict them. However, universal claims can be falsified (proven false) with a single counterexample. Once a universal claim is falsified, it leads to a particular claim like "Not all swans are white," which can be verified by specific evidence.

In essence, universal claims cannot be proven true because they generalize across all cases, while particular claims can be proven once a falsifying counterexample is found. That's why you can "prove" the statement "Not all swans are white"—it’s based on specific evidence from reality, in contrast to the uncertain generality of universal claims.

To sum it up. When I say nothing can be proven and things can only be falsified... it is isomorphic to saying universal claims can't be proven, particular claims can.

In that sense, it's also correct to say that physicists have knowledge of relativity and quantum mechanics. I don't think any physicist including Einstein himself thinks that either theory is actually true, but they do have knowledge of both theories in much the same way that one has knowledge of "Maxatar's conjecture" and in much the way that you have knowledge of what the flat Earth proposition is, despite them being false.'

It seems fairly radical to believe that instrumentalism is indefensible, or at least it's not clear what's indefensible about it. Were NASA physicists indefensible to use Newtonian mechanics to send a person to the moon because Newtonian mechanics are "wrong"?

What exactly is indefensible? The observation that working physicists don't really care about whether a physical theory is "real" versus trying to come up with formal descriptions of observed phenomenon to make future predictions, regardless of whether those formal descriptions are "real"?

If someone choses to engage in science by coming up with descriptions and models that are effective at communicating with other people observations, experimental results and whose results go on to allow for engineering advances in technology, are they doing something indefensible?

Every other time you've been in that school building, the clocks have shown you the right time, so you feel very confident that the clocks on the wall are accurate.

But this time, you happen to be in the room with the non-functioning clock. It says "2:02" but by great good fortune, it actually happens to be 2:02.

So your belief is:

1. True. It actually is 2:02.

2. Justified. The vast majority of the time, if you see a clock on a wall in that building, it is working fine.

But should we say that you know the time is 2:02? Can you get knowledge of the time from a broken clock? Of course not. You just got lucky.

In order to count as knowledge, it has to be justified in the right way, which, alas, nobody has been able to specify exactly what that way should be. So far, nobody has come up with criteria which we can't find break in a similar way.

// all you can justify is that there is the likeness of a cow there //

If you see something which looks real, you are justified in believing it is real. If you see your friend walking into the room, sure, you've seen your friend's likeness in the room. But you are justified in believing your friend is in the room.

So if you see something that looks like a cow in a field, you are justified in believing there is a cow in a field, even though looks may be deceiving.