are determinists irrational, wrong or both? or are they right?

Here's my response to this video:

http://www.youtube.com/watch?v=G3UYZcwUEfw&feature=player_embedded#at=482

This is my understanding of Stef's argument: he is trying to discredit Determinism by assuming it's true and then showing that its logical conclusions are nonsensical or impossible to swallow.

1. Given: The future is set.
2. When you argue, you assume you can change the person's mind.
3. If you can change a person's mind, then the future is not set.
4. Therefor, your assumption that you can change someone's mind is wrong.
5. Therefor, you will never achieve your goal of changing someone's mind.

I think there's a troubling truth buried in what he's saying. But before I get to that, I'd like to examine some of his premises.

2. When you argue, you assume you can change the person's mind.

Is this always the case? I don't think it is with me. Sometimes I'm arguing almost as a reflex action. I know Stef is talking about a rigorous, logical debate -- not chest-beating. But if you've used logic for years, you can often employ it without thinking too hard about doing it or why you're doing it.

I often argue to work through something. I may not care about convincing you as much as I care about figuring out something for myself. You become a tool to help me do that.

However, those are minor objections. In general, I agree with you that people who call themselves Determinists (myself included) often argue with the goal of changing someone's mind.

3. If you can change a person's mind, then the future is not set.

This is not true. Here, Stef is (maybe unintentionally) playing on ambiguity in the word "change." Just using that word sounds as if we've already rejected Determinism. If someone chooses to change his mind (based on listening to your argument), he must have free will. But notice how I slipped the word "chooses" in there. (To be fair to Stef, he didn't use that word. I am claiming it's implicit in his argument.)

Change occurs whether free will exists or not. Stef likes to bring up rocks. So imagine a rock rolling straight down a hill. If you try to predict its course, you'll say it's going to land roughly parallel to where it started, but at the bottom of the hill instead of at the top. But what if another falling rock hits it on its way down. That second rock may "change" the first rock's course. All "change" means in this sense is that objects can affect each other. The first rock veered to the left instead of going straight down BECAUSE the second rock hit it.

Now, if the universe is determined, it also means that our original prediction was just wrong. We predicted that the rock would end up parallel to where it started. We did that because we were unaware of the second rock. Truthfully, the second rock didn't change anything. It didn't alter history. It just did what it was determined to do which led to the first rock doing what it determined to do. There was NO chance that the first rock could have EVER landed parallel to where it started. In fact, the concept of chance is meaningless.

In a determined universe, it's NOT true that a specific coin has a 50% chance of landing on its head or on its tail. We may have a 50-50 chance of GUESSING how it was determined to land*. But if it lands on its tail, that's how it was "fated" to land. If we could rewind the universe and watch it land over and over, it would always land on its tail.

*In a determined universe, it's more accurate to say that 50% of our guesses we're fated to make will wind up accurately predicting the way the coin will fall.

But it's still true that the rock went left BECAUSE it was hit be the other rock. Why? Because (a) the other rock hit it and (b) rocks have certain properties that cause them to be affected when they are hit by other solid objects. (If a rock hit a cloud, the cloud probably wouldn't change course.)

Humans are "built" to be affected by certain inputs. Those include "arguments" from other humans. Rocks aren't built to be affected by those same inputs. Stef says it's crazy to yell at a rock. That's correct. But the reason it's correct has nothing to do with free will or Determinism. It's correct because rocks have no internal mechanism for receiving or processing arguments.

My computer is a Deterministic device. But it can't respond to me waving at it.

So Stef's clam (or my rewording of it) that "If you can change a person's mind, then the future is not set" is nonsensical. You can CAUSE a person's mind to do certain things by doing certain things to that mind. No one -- free willer or Determinist -- is arguing that human minds can't receive and process inputs, and that they're not changed by those inputs.

Now, here's where I think Stef is onto something: even if it's possible for one person to cause another to reach some conclusion, in a deterministic universe, the causal person is himself caused. In other words, I'm not really arguing with you "to change your mind."* I'm arguing with you because I'm determined to argue with you. And though the sounds I make will likely cause some sort of behavior on your part, you're ultimately going to do what you're going to do -- just like the coin.

*My desire to change your mind might be a causal factor that makes me argue with you. By saying "I'm arguing TO change your mind," I am stacking the deck. Alas, our language is full of traps that assume free will. What's true is that (a) I have a desire to change your mind; (b) I'm arguing with you. Maybe (a) caused (b).

Stef is right that Determinists often assume everyone is determined except them, which is wrong. You most often hear that argument in this form: "If Determinism is true, should we punish people who commit crimes?" What that really means is "If Determinism is true, should we freely CHOOSE to punish people who commit crimes?" Of course, if Determinism IS true, we will or we won't punish people who commit crimes, depending on what we're determined to do. The question creates a world view in which everyone is determined except for the questioner. I agree with Stef that's absurd. (It's also a common mistake.)

I believe we (including me) are determined. When we argue, we are determined to argue. And when the clockwork universe causes us to argue, the sounds and gestures we make often cause various behaviors (and internal states) in the people we're arguing with.

Finally, I'd like to look again at (my version of) Stef's argument:

1. Given: The future is set.
2. When you argue, you assume you can change the person's mind.
3. If you can change a person's mind, then the future is not set.
4. Therefor, your assumption that you can change someone's mind is wrong.
5. Therefor, you will never achieve your goal of changing someone's mind.

Let's assume that we completely agree with this. Okay, well then it proves that Determinists are irrational. That's fine, but that doesn't prove anything about whether free will exists or whether the universe is deterministic. If I say "Rocks fall downhill because invisible gnomes pull them down," that's irrational, but the fact that it's irrational does not change the fact that rocks fall downhill.

At most, Stef is saying something interesting about Determinists (they can be inconsistent). He is not saying anything about whether the universe is deterministic. He is not giving a shred of evidence for free will. Saying that believers in something tend to be (or even MUST be) irrational says nothing about whether the thing they believe is true or false.