Determinism vs. Free Will
This is the way I look at systems that behave according to a determine system of rules and systems that actively make decisions.
In chemistry, molecules automatically pursue the lowest energy state possible...hence the influence of entropy. In quantum mechanics, some electronics seem to already "know" what is the best possible path to get from point A to point B. These are systems that behave according to scientific law, a pre-determined set of rules, in essence, cause and effect.
Nature is incredibly smart, molecules and atoms always choose the state that is most favorable to them...they obey the laws of cause and effect; human beings don't always...that's the strongest proof of free will.
If you want an actual example, think of all the stupid people you see on a daily basis? How many stupid things have you done in your lifetime?
Molecules and atoms always choose the course of action that's optimal for themselves, human beings almost never do.
Another proof of free will is that systems that obey a set of laws, any set of laws, show a repeated response to stimuli.
To prove that human beings do not show a repeated response to stimuli, try kicking one of your co-workers in the shin. First time "ouch, stop." Second time "ouch, stop." Maybe even a third time "ouch, stop." Fourth time, you walk away with a bloody nose.
Why do you think the phrase "Too much of a good thing" has become even slightly prominent? Because something can be good the first few times you do it, and then you get tired of it.
Why do you think that computers were invented? Because they are really good at doing repetitive tasks and human beings aren't. Human beings are still more intelligent than computers, but computers can do millions of calculations a second.
You could argue that some people are just better at determining the mathematical odds of situations than others are, and that's what some people are considered "stupid" and why some people are more successful.
First of all, I'd just like to point out that you can't use mathematical odds to determine every decision you make. Example, go out to dinner. Look at the menu and try to use math to make your decision. You could look at the prices and choose the price that's optimal for your particular situation. What if all the prices were the same? Would you try to calculate the chances of one particular meal giving you indigestion vs another? Try putting your appetite in terms of numbers. It's not that easy. Of course, you could rate on a scale from 1 to 10, but not everyone's favorite meal is the same. I suppose to you could go through life putting everything on a scale from 1 to 10, but who wants to wake up as Dave Letterman every morning?
Another proof of the existence of free will is that some people can be incredibly intelligent, calculate the odds of a situation perfectly and still choose a course of action that's not optimal to them. Look at the instances of altruism. I know they are few and far between, but they do exist. Ask a Vietnam vet if they have ever heard a G.I. throwing himself on a grenade.
If that G.I.'s decision making process was controlled by calculating mathematical odds in order to make the optimal decision for himself, then he chose the course of action that was completely opposite of optimal.
If you want to say "well, it was determined that he was going to throw himself on a grenade, he didn't actually make that decision." Then just the same as saying "It was determined that he would have free will."
If you want another example, think of your mother. She carried you for nine months and then went through the horrible pain of giving birth to you when she could have had an easier time having the brains sucked out of your skull before you were even able to take your first independent breath. Not to mention she could have spent most of her life traveling around world, pursuing a career, or anything else she wanted instead of teaching you to feed yourself for 18 years or more.
Yet another proof of free will is to simply look at the implication of everything being determined by a series of causes.
If everything is determined by a series of causes, why complain about George Bush's decisions as president? He can't help it. Those decisions were made as soon as the big bang occurred. Did some guy break into your house and steal the things you worked for? You can't complain, that guy isn't responsible for his own actions.
Basically, if you consider determinism is true, every criminal is given a carte blanche and every charitable person's actions count for nothing...including your mothers. She didn't love you, she was just reacting to a cause.
Every criminal could then walk into a courtroom and say "My actions were determined, I didn't have anything to do with it" and then walk out again.
If you're married, there's nothing special there, right? You were just reacting to a stimulus, it doesn't mean anything.
If you're going to say that every decision you make is just maximizing the situation for yourself, then every relationship that has ever existed is simply manipulation.
Your mother gave birth to you because she wanted someone to help her do the housework, not because she actually cared anything about you.
My arguments could have been presented in a more organized fashion, and probably worded more suitably as well, but this is just an online forum. Before you say things like "everything is determined", take a look around you and at your own life and see if that's actually the case. If you say that something is true, then it has to repeatedly true in various situations. That's my beef with moral relativism...it wouldn't even hold up under scientific standards, much less philosophical standards.
Scientific laws are tested based on their repetition...an experiment can be repeated millions of times with the same result, but there is NOTHING that requires the same result the next time you do the experiment.
If you put moral relativism to the test, then you get not repetition whatsoever, you get a different result everytime.