The Law of Identity and the Law of Substitution

I'm absolutely fascinated by motivation. What motivates me to be fascinated by motivation? I like the idea of power surrounding it.

Je te presente The Philosophical Law of Identity.

The Law of Identity states we can identify something; and substitute it in later. This is cooler than it sounds.

The Law of Identity gets expressed basically as x = x, or other inane obvious ways. But this stuff is more subtle and interesting than that.

Check out this philosophical classic by Bertrand Russell:
http://en.wikipedia.org/wiki/On_Denoting


If I told you that gravity is bodies being attracted to a larger body; and that bodies being attracted to a larger body is gravity; You would say, "Bum rap! That's a terrible answer!"

But in order to give any truthful answer ever, you would have to have an answer that is a true proposition. I know this could be explained better but I'm going to let you chew on that.

And sometimes it can be good to identify something as is. There is some strength in saying an apple = an apple; or x = x


The Law of Identity is closely related to, and this is going to sound heartbreakingly obvious, The Law of Substitution.

For example, in a basic informal proof, we could say that x = (y+z). Then every time we have an x, we can get y+z. This is akin to the point in the Harry Potter movies where he learns to raise his wand and turn an apple into a goat. But even cooler!


The big guy for all of this, again, is Gottfried Leibniz.



Aristotle's big three Logic laws were:

Law of Contradiction (Never P and not P)
Law of Identity (P = P)
Law of Excluded Middle (P or not P)