"Know" means know

When people say "I do not think it, I know it," they are usually saying that they are sure of something. And even philosophers regard what they are sure of as knowledge. What if what they are sure of is not actually the case? Well, everyone thinks that what they personally are sure of is the case: that is what it means to be sure of something.

But what if I am sure of something fairly complicated, and you think that what I am sure of is not actually the case. Would you say that what I had was probably some knowledge beyond your powers of understanding? Or would you think it more likely that I had a complicated kind of ignorance?

Almost everyone thinks that a belief must be true if it is to count as knowledge. And philosophers noticed, a while ago now, that there is more to knowledge than certainty and truth:

What if I am sure that it will rain on my parade, and it does. Would you say that I knew that it would rain? Or do you think it more likely that I was just being pessimistic, and unlucky?

For such reasons, philosophers have been debating how they should define "know"; for my thoughts from nine years ago, click on this link. More recently, I have been thinking about scenarios like this:

By the end of the nineteenth century, physicists were sure that, thanks to Newton, they knew the most general laws governing how physical objects move, but thanks to Einstein, our physicists are now sure that those physicists did not know as much as they thought they knew.

Still, it is possible that physicists, in a thousand years time, will discover that it was only some dark ether, or something even stranger, that had made things look Einsteinian. It is possible that those nineteenth-century physicists did, after all, have a lot of knowledge.

Indeed, all sorts of things that we cannot even imagine might be discovered in a thousand years time. The problem is that we can only judge how likely such future discoveries are by using the knowledge that we are now taking ourselves to have. Philosophers are therefore making sure, as best they can, that what they think they know is indeed knowledge:

Philosophers tend to define "know" by constructing axiomatic models of knowledge, so they do seem to be pursuing the truth in a scientific manner (not too dissimilarly, physicists construct mathematical models of physical systems in order to understand them).

But could philosophers pursue the truth about knowledge if they did not already know what truth and knowledge were (note that physicists do not need to know what matter is in order to discover the laws that govern its movements)?

Is there something about truth and knowledge that philosophers do not understand as part of common sense, and cannot come to understand by logical introspection or by asking psychologists, sociologists and linguists?

Well, I suppose that it would be quite mysterious how people could possibly know truths about the world if people were nothing more than highly evolved animals in a purely physical universe. But then, that is why philosophers should not ignore a logical proof that in all likelihood, that is not what we are: logic dictates that in all likelihood, we are incarnated souls (not too dissimilarly, logic dictates that in all likelihood, Fermat's last theorem is true).