Which tells us that logic can force us into believing some puzzling things.
One of those things is the belief that evidence for a proposition, no matter how narrow the proposition is, can be found literally everywhere. Although logically, there should be no connection between two disparate ideas.
Take the proposition “all ravens are black.” What would count as evidence of this theory?
It’s simple right? The more black ravens you find, the stronger the proposition is.
Except that the proposition can also be construed to mean “if something is a raven, it is black.” This also leads to the statement “if something is not black, it is not a raven.”
So now we have more than just ravens to look toward for evidence.
We know that we can examine ravens by looking for black things, since ravens must be black. This opens up every black thing as evidence of our original statement.
We can also examine ravens by looking at anything. Because we reworded our original statement “all ravens are black” to mean “if raven, then black” and “if not black then not raven.”
So we can now examine not only ravens, but everything that is black and everything that isn’t black.
In other words, everything that exists.
The paradox here is that this doesn’t sound correct. Can the fact that my desk is black or that my shirt is red really support the theory that all ravens are black?
It just doesn’t seem possible that such disparate things should have any logical relation.
Yet almost 100 years after the theory was proposed, there is still no definitive solution.