So today we had a lovely little philosophy lesson on the nature of knowledge and truths, and I figured it'd be thrilling to share my tidbits of wisdom with you lucky bunnies. Have fun, this one's going to get technical.

Why You Can Be Certain Of Nothing

I'm just gonna stick this out there now: "You know nothing about the world."

There, now we've got that over with, let's explain exactly why.
You lucky children are about to get a crash course in the fundamentals of Solipsism, the laughing stock of philosophy.
Solipsism is to philosophy what a doormat is to a farmer's manure-smothered boot.
Solipsism is the kind of subject where, if you bring it up in an argument and expect to be taken seriously, everyone will shoot a sympathetic glance at your parents and ask "How long as he been like this?"
And the worst part is, it's totally irrefutable.

The entire thing hinges on the fact that our senses are flawed. Our only way of gaining knowledge about the world is through our senses, and how the hell can we know if they're doing it correctly? We can't check if they're correct or not, since in order to do so we'd need some way of comparing our perceived reality to the genuine reality, and we have no way of doing that which doesn't further utilise our senses, which would just make our 'genuine' reality another perceived reality.

It's like asking a blind man what colour a house is, and when you want to check if he's correct, you decide to check yourself, but then you remember you're blind as well. Obviously you're dumb for forgetting such a blatantly obvious flaw in the first place, but the end result is, without some kind of external source of information, how can either of you know what colour the object is? Even if someone who could see told you, for all you know, they could be lying.

Get it? Since our senses, our only ways of gathering information, are fundamentally unreliable and can't be completely trusted, how can we be certain of any information we gather with them being correct?
Sure, they're probably pretty accurate for the most part, but you can't be 100% certain. And that's the important bit.

As I mentioned earlier, it's totally irrefutable. There is nothing you can say to conclusively disprove it, since the arguments you form would all be based on information gathered through this distorted lens. While it's perfectly possible that the arguments you'd make are valid, you can't actually KNOW they are.

Of course, most philosophers think this is pretty dumb. Yeah, sure, technically we can't know anything, but it's all fairly irrelevant isn't it? Instead of moaning about our ignorance, shouldn't we just try to gather as much knowledge and truth as is reasonably possible given our situation? Sure, we can't technically be absolutely certain of something, but we can still be as certain as it is reasonably possible for a human to be. That's why people don't like it. They all have to grudgingly accept it's there, but they prefer to ignore it. Like a stupid little tumour on an otherwise beautiful subject.

So that is why, technically, you know nothing.

Why You Know Everything

Has somebody been telling you that you know nothing? Don't be ridiculous. That guy must be an idiot. Not only do you know things, but you know everything, and this is why.

The last bit was the simple bit. This is where you actually have to start thinking. Solipsism is really very basic, this is where they weird stuff happens.

Now, let's start off with a proposition:

"There is a green folder on the desk in front of me."

Now, I could be wrong there. According to solipsism, I could actually be seeing a red folder which my senses are telling me is green, or perhaps it isn't a folder and it's actually a cat. My senses could just be failing me.
However, there's a loophole. It's all centred on definitions.

In order to know that the above proposition is true, I need to know three main things.

-I need to know what the colour green is.

-I need to know what a folder is.

-I need to know that it is on the desk in front of me.

Now, this all comes down to what is and isn't truth.
There are many categories of truth, and for the most part, they come in opposing pairs.

Analytic truth is something which logically MUST be true. Something which cannot possibly be disputed, since it is true by definition. A example of this would be "All bachelors are unmarried."
Of course all bachelors are unmarried. By definition, a bachelor is an unmarried person. Another way of phrasing that would be "All unmarried men are unmarried."
It's like going into an algebra exam and answering every question with "X=X". It absolutely cannot be wrong. It is the truest of truths.

And then there is contingent truth. Contingent truth is so named because it is contingent upon certain factors. According to my philosophy teacher (and I say that for good reason, since I think this is flawed), a good way of deciding if something is a contingent truth is to consider whether it could possibly be any other way.
The example my philosophy teacher used was "Tony Blair was the prime minister of the UK."
For those of you who don't know, he was.
Now, my teacher's argument was that, since it was always possible that he might have not become prime minister, but instead specialised in growing funny-shaped peanuts for a living, or maybe fixing broken windows, the fact that "Tony Blair was the PM of the UK" must be a contingent truth. It is a possibility that, in another, parallel universe, Tony Blair was never the prime minister at all.

I, however, believe that these are really fundamentally the same thing. Bear with me here.

Now, in order to prove this, you must first consider what we define "Tony Blair" as. Tony Blair is a specific man, made out of specific elements and atoms and whatever, with a specific personality and specific ideas. If we were to have a huge database of everything in existence and we wanted to pull up 'Tony Blair,' we could first search "Earth," then "Humans," and then "Tony Blair" and then key in the specific personality and specific particles from which he is composed. From that we could pin this exact, specific man.

So the object is defined by its properties. A word is meaningless until it describes something with properties. I could tell you that I saw a sunt the other day, but it would mean nothing to you until I explained to you the properties of a sunt. They will remain a mystery for now, but you get the idea, I hope.

I like to think of it a bit like factors. Every number has a factor or factors, and when you combine those specific factors together, so long as the factors are the same, you will always end up with the same, specific result.

So then his argument that "In another universe it is possible that Tony Blair was not the prime minister" is effectively moot. After all, that man would not be Tony Blair. That man would be someone other than Tony Blair. Tony Blair is a specific man in a specific universe, with specific properties which make him specifically himself. Specifically.

It's entirely irrelevant, in my opinion, to talk about "In another universe" when it comes to this, because the fact of the matter is that we are NOT in another universe, we are in THIS universe, and so too are all the things we have ever seen and will ever need to reference. When you talk about something, you are talking specifically about that thing as defined by its properties, and if it were to have any different properties, it would no longer be that thing.

Say you took a square. What defines a square? A geometric , 2-Dimensional shape, composed of four straight edges of equal length, with 90 degree angles at the corners. I imagine there are some nitpicking ways of making that technically something other than a square, but those are the main properties which come to mind, and they will serve the purpose of this analogy.

Now, if you took the square, and changed its property of "four sides" to "three sides," it would no longer be a square. Squares, by definition, have four sides. To make it three sided would to make it no longer a square, and if you pointed at this shape and said "That's a square," you would be incorrect, since it is definitely not a square. You can no longer reference it as a square once one of its fundamental properties which make it square have changed.

Likewise, if you took a red square, and you made it blue, it would no longer be a red square. According to the definition of red, it must reflect a specific wavelength of light in order to be red, and any other wavelength would not be red.

You can compound the effect by adding increasingly specific properties, and the principle remains the same. Objects and ideas must be defined by their properties.

So it seems that, according to the Tony Blair further up in the blog, contingent and analytic truth are really the same. Everything must be a logical certainty, since everything, when you break it down into its properties, is just another "X=X" argument.

Just as X is always equal to X, Tony Blair is always equal to "A man made of these specific particles, with this specific personality and appearance, who was prime minister at this specific time."

His prime-minister-ness is just another of his properties. It makes him him.
If he were, in another universe, to have never been prime minister, it doesn't matter if this alternate person was also named "Tony Blair," and it doesn't matter if his personality was identical to the personality of our Tony Blair, because that one changed property makes him no longer the person we are defining.

I know the folder on the desk in front of me is a folder, because it fits the definition of a folder. It doesn't matter if on another planet they call folders "Snarglewoops," nor does it matter if in another universe all folders are actually cats, since I'm not talking about their definitions, I'm talking about the human definition of 'folder' in THIS world, and that is all that matters.

I also know that said folder is green, since it fits the definition of being green, and I know it is on the desk in front of me, since it fits the criteria of being on a desk in front of me. I know this for certain because it is a logical, analytic certainty. A necessary truth, or a tautology.

So in the end, all truths which are truly truths are logical certainties, and everything we do know, we know for certain.

Why it doesn't really matter all that much anyway

Nobody with their priorities straight gives a crap about whether or not said folder is actually a folder, or if it's secretly a cat in disguise, all they care is if it has any money in it, or if it's edible, or if snorting it through their nostrils will make them have happy daydreams.

Frankly, it really doesn't make a difference. Go out and do something practical with your life.