Can we predict human decisions with absolute certainty?

[Jagella]

Depending on what you might mean by “prophecy,” it may or may not be possible. We can all make plans that we fulfill, and we can make some good guesses. Extrapolation in some cases may also work very well in predicting the future. Astronomers can very accurately predict where some celestial body will be in its orbit at some time in the future.

But, can we make 100 percent accurate prophecies about less predictable events such as human decisions? What makes predicting human actions so problematical is that people may have some element of free will. If you offer me mashed potatoes at dinner, I may choose to accept the offer or decline the offer. Can you know for certain what choice I will make?

To answer this question, let's say that you have the ability to know the future for certain. In that case, you can know for certain that I will accept the offer of the potatoes or decline, but what if you tell me what I will do? If, say, you tell you that I will accept the offer, I might prove you wrong by declining! Of course, if you're still right about your prediction, then I must accept the offer of the potatoes. I have no free choice.

At this point it seems that prophecy and free will are not compatible. If the future can be known for certain, then we must live that future. We cannot choose to defy the prophecy.

I do see a way out of this predicament, though. Whoever knows the future can still know it for certain if she does not divulge it! That way nobody can defy the prophecy because they don't know how to defy it, and we all keep our free will. Interestingly, we see this very tact being taken in the prophecy given in Matthew 24. Jesus declines to predict the time of the apocalypse stating: “No one knows about that day or hour, not even the angels in heaven, nor the Son, but only the Father.” You might be cynical and say that the writer of Matthew declined to state the time of Jesus' prophecy because he was no real prophet. However, the time of the prophecy may have been legitimately kept secret because of the problem of people defying the prophecy if they know the time of the prophecy's fulfillment.

Even an omniscient God, it seems, has his limitations. Even he must keep secrets for purposes of security.

Jagella

 

[FlexGunship]

Depending on what you might mean by “prophecy,” it may or may not be possible. We can all make plans that we fulfill, and we can make some good guesses. Extrapolation in some cases may also work very well in predicting the future. Astronomers can very accurately predict where some celestial body will be in its orbit at some time in the future.

But, can we make 100 percent accurate prophecies about less predictable events such as human decisions? What makes predicting human actions so problematical is that people may have some element of free will. If you offer me mashed potatoes at dinner, I may choose to accept the offer or decline the offer. Can you know for certain what choice I will make?

To answer this question, let's say that you have the ability to know the future for certain. In that case, you can know for certain that I will accept the offer of the potatoes or decline, but what if you tell me what I will do? If, say, you tell you that I will accept the offer, I might prove you wrong by declining! Of course, if you're still right about your prediction, then I must accept the offer of the potatoes. I have no free choice.

At this point it seems that prophecy and free will are not compatible. If the future can be known for certain, then we must live that future. We cannot choose to defy the prophecy.

As far as anyone can tell, human decisions are based soley on external stimuli and previous conditioning states of the brain (which were, in turn, based on external stimuli). If you knew the exact state of the universe in every detail from the moment a human brain began to function (go ahead and eat it Heisenberg), then there seems to be no reason why you couldn't predict the brain's repsonse to a certain set of stimuli at a given moment.

Do not mistake complexity for unknowability.

I do see a way out of this predicament, though. Whoever knows the future can still know it for certain if she does not divulge it! That way nobody can defy the prophecy because they don't know how to defy it, and we all keep our free will. Interestingly, we see this very tact being taken in the prophecy given in Matthew 24. Jesus declines to predict the time of the apocalypse stating: “No one knows about that day or hour, not even the angels in heaven, nor the Son, but only the Father.” You might be cynical and say that the writer of Matthew declined to state the time of Jesus' prophecy because he was no real prophet. However, the time of the prophecy may have been legitimately kept secret because of the problem of people defying the prophecy if they know the time of the prophecy's fulfillment.

This sounds religious; I won't be touching it...

Okay, I'll touch it a little: the funny thing about not being able to predict the end of the human species is that it seems we all have that in common. I would certianly refrain from arguing that the strongest argument in favor of a prophecy is the lack thereof.

In that case, you might as well pay me my gambling winnings now.

Even an omniscient God, it seems, has his limitations.

The greatest of which is obvious...

Even he must keep secrets for purposes of security.

Hah... yes. I have an invisibile pink unicorn that doesn't tell me things either.





Ugh... I can just smell an infraction...

 

[Ryan_m_b]

I'm going to ignore the religious stuff because it's trivial. As to future predictions there are three things you need:

• Comprehensive data collection
• Thorough understanding of the processes underlying the phenomenon in question
• Adequate computational resources

In other words if you had a http://en.wikipedia.org/wiki/Theory_of_everything" as well as an omnipresent sensor and an unlimited computer you could predict everything. The problem is whilst we may one day get the first one the latter two are impossible, as well as that you still have to have an understanding of the phenomenon you are looking at (a TOE is useless if you are trying to model behaviour and don't have the ability to look at a person in atomic detail).

Therefore future predictions are always going to limited by the ability to gather data, understand how to build a model and have the resources to model it. This is complicated by the fact that if we ignore the hypothetical perfect system outlined above any prediction is going to be under the control of http://en.wikipedia.org/wiki/Chaos_theory" .

 

[Jagella]

As far as anyone can tell, human decisions are based soley on external stimuli and previous conditioning states of the brain (which were, in turn, based on external stimuli).

I think this theory may be correct. It does seem that human behavior is “hard wired” and that free will is an illusion. Why, for instance, is antisocial behavior so common? If people could really choose what actions to take, then why would people choose to be cruel or unjust?

If you knew the exact state of the universe in every detail from the moment a human brain began to function (go ahead and eat it Heisenberg), then there seems to be no reason why you couldn't predict the brain's repsonse to a certain set of stimuli at a given moment.

I think I'll stick with Heisenberg. Quantum mechanics demonstrates that God does play dice with the universe, Einstein notwithstanding. Human will may be a macroscopic demonstration of quantum uncertainty. Will isn't free—it's merely unpredictable.

This sounds religious; I won't be touching it...

I should point out that I'm an atheist. I used an example of alleged prophecy from the Bible because it's a well known example of a prediction that many people believe is accurate.

Hah... yes. I have an invisibile pink unicorn that doesn't tell me things either.

You may have your unicorn as long as she is not impossible. A God who refuses to fully inform his followers as to the “end times” is not impossible although arguably unlikely to exist.

Jagella

 

[Evo]

At this point it seems that prophecy and free will are not compatible. If the future can be known for certain, then we must live that future. We cannot choose to defy the prophecy.

Prophecy is a supposed glimpse of a future event. It is merely anecdotal. Is your argument that a "prophesy" is the actual future? This thread is in it's final death throes BTW.

 

[DaveC426913]

Even an omniscient God, it seems, has his limitations.

The greatest of which is obvious...

 

[DaveC426913]

Sorry, if he who knows the future but does not divulge it then he has not made a prophecy.

You have not fulfilled the criteria for a prophecy to occur.

 

[Evo]

And the thread kill goes to (drum roll please)... Dave!