Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is everything predictable?

  1. Jul 3, 2003 #1


    User Avatar

    I thought about this the other day..

    There's a part of our brain that we have no control over. It takes care of the essence of life: reproduction.

    If everything we do is based on that psycholocigal drive, then everything is predictable. One thing leads to the next.
    The cycle of life is a very complex calculation.

    If you can calculate something, is it predictable?

  2. jcsd
  3. Jul 3, 2003 #2
    You are raising the issue of determinism, that is to ask the question, when we assume for instance that we would have access to all possible measurements about all matter, and have access to all laws describing how the material world interacts, if we could then in theory calculate all the events taking place thereafter.

    We could apply this idea for instance to: weather forecasts or our phychological behaviour.

    Physics answers to this being possible with a clear no. And not just for practicle reasons (because we can never gather all the data needed for such calculations) but for theoretical reasons.
    Quantum mechanics shows us that certain types of experiments are unpredictable.

    Therefore the idea of total determinism, has been left.
  4. Jul 3, 2003 #3
    Welcome to the PFs, goo! :smile:

    I have one question for you, before I begin responding to your question, why do you posit that we have no control over the part of our brain that controls reproduction?
  5. Jul 3, 2003 #4

    Totally and completely incorrect. If there's one thing that chaps my ass it's people making a proposition based on incorrect information.

    To say there is a part of the brain that takes care of reproduction is ABSURD. there is no such part of the brain at all whatsoever!

    Where in the living hell did you hear this misinformation>
  6. Jul 3, 2003 #5
    Re: Re: is everything predictable?

    LOL. Alright now, calm down. I too was a little thrown off by this, but I just assumed there was something I didn't know yet.
  7. Jul 3, 2003 #6
    Re: Re: Re: is everything predictable?

    No, he's just completely incorrect. There is NO such part of any creatures brain.
  8. Jul 3, 2003 #7
    Obviously, there are parts of the brain concerned with reproduction, or we wouldn't have the desire to have sex or children.
    Just because we can't predict what's going to happen doesn't mean that there is no cause and effect. It could be that we just don't know all the factors affecting the outcome.
  9. Jul 3, 2003 #8
    That's what I had thought but, strangely enough, I was actually intimidated by someone I felt had greater knowledge on the subject. Hmm. Well, I can assure you it wont happen again.

    Anyway, I would say that the pituitary glands should be involved, since the chemical messages that induce sexual stimulation are produced there, are they not?
  10. Jul 3, 2003 #9
    That caught my attention too Mentat. Goo, I'm not sure about everything we do being based on psychological drive either. If, by that, you mean instinctive urge, then we do have choices. We can decided not to do what our biology is urging us to do. We can, to some extent, even condition those biological urges over time - nurturing some and lessening others.

    That being said, there's still the issue of, if our brains are made up of particles, and laws define particle interaction, then aren't all of our choices an illusion and really predetermined?

    This of course, has been addressed by heusdens above, who rightfully points out that modern quantum mechanics has determined that, on a fundamental level, quantum particles are truly random (and not just "called" random because we don't know how to predict their behavior). This would mean we do not live in a deterministic universe.

    But not a totally random one either, because all of these random events sort of "average out" on the larger level, leaving us with general likelihoods for various events, which never truly reach absolute 0 or 1. I like to think of it like dice. You roll one and you can get a 1-6. Each is equally likely so it's completely random. You roll 2 and now there's a bell curve for the total. It is more likely to see a 7 than any other number, which would mean an average roll of 3.5. The more dice you roll at once, the higher the bell curve spikes, making 3.5 more and more likely as the average. Thus, when rolling ten thousand dice at once, and averaging together the rolls, the odds of it being 3.5 are incredibly high. Inversely, when you roll 2 dice you will often see a total of 2 (average roll of 1 each). But the odds of seeing all "1's" when rolling ten thousand dice are SUPER unlikely (I'll spare myself the calculation since it's not important). Particles are the same. This means, with billions and trillions of quantum particles making up our everyday world, things average out, and the odds of a macro-sized object not performing according to Newton and Einstein is so slim as to be ingorable.

    But there are exceptions from what I understand. These exceptions happen in complex or unusual structures where a "chain reaction" can be set up. In fact, a lot of particle detectors are just such an example. They are set up in such a way where the performance of one particle, causes a chain reaction that affects large-scale objects (such as computer readouts and paper printouts of particle activity, where you have a large ink pattern on a page, simply determined by the performance of a single particle). Brains might (MIGHT) be such a structure in and of themselves as well due to their complex neural networks, and the complex structure within single neurons. For example, single particles may have minor effects, which then cascade up the network to affect neuron firing and lead to larger activity.

    If this is true, then our behavior would still be one of odds, making certain behaviors more likely than others, but that would be tempered by a slight propensity for the random firing, leading to unexpected brain activity. This would, in effect, make us free agents, not bound by mechanistic determination.

    Then there is the issue of, is randomness really "free will"? Or are we just as robbed by randomness as we are by determination? When you look at it this way, as a friend pointed out to me, it doesn't really matter what's going on, on a particle level. The "will" is a multi-component phenomenon. Will exists on a higher detail level and is the result of several parts interacting. Therefore, if a choice is made by that functional process of "will", then we have free will, regardless of determinism.
  11. Jul 3, 2003 #10

    Parts involved in reproduction isn't the sane as parts FOR reproduction.

    Get it?
  12. Jul 3, 2003 #11
    Hey goo. Welcome.

    Anyhow, no there is not a section of the brain dedicated specifically to reporduction. I think you're the victim of an "urban legend" there:wink: But it's not totally inaccurate. certain fuctions of the brain in part relate to that function, such as the pituitary gland. And that goes to more basic function of the human mind. It's primal, like eating, or self-preservation instinct.

    However we can choose to not reproduce. It's called Birth control
    With human behavior, you cannot predict something with absolute accuracy. There will always be a degree of error due to human emotion, which is very unpredictable. You can calculate probabilty, but not absolutely.
  13. Jul 3, 2003 #12
    Sorry, but homosexuals have been proven to have distinctly different brains. Reproduction is important to perpetuation of the species, but is not an issue on an individual basis nor even the central issue for a species. Evolution is the issue for all of us on both an individual and collective level.

    Every species and individual dies. We are born, we live, and we die. The question is not how to reproduce ourselves like so many flyers to be pasted on parking lot windshields, but from moment to moment where do we go from here.
  14. Jul 5, 2003 #13
    Re: qm & determinism

    I wouldn't say that physics has completely dismissed the notion of determinism. There are still many physicists today that believe there exist "hidden variables" that we cannot observe that account for the behavior of particles in the quantum realm. David Bohm's magnus opus is a completely deterministic view of quantum mechanics which uses a "quantum potential" as the hidden variable. In this theory the path of an electron through the slits in the famous double slit experiment is a consequence of chaotic behavior rather than some inherent randomness in nature. There are a few experiments that supposedly have been designed to test for this, most notably the ones in the 80s testing John Bell's inequality for particle spin. All of these have generated data in favor of Quantum Mechanics, and not in favor of the determinists' view. But from what I understand (correct me if I'm wrong), there are those that still feel there have not been adequate tests for this theory, and that it may not even be possible to design an experiment to test for it. Anyways, long story short, if the "hidden variables" idea is true, then it would appear that everything is determined, from interaction of atoms and molecules to our behavior.
    Last edited by a moderator: Jul 5, 2003
  15. Jul 5, 2003 #14
    Re: Re: is everything predictable?

    Not this old argument about homosexuality and hereditary vs environment. I'm a firm believer that it's all psychological. I'd like to see this proof of these discoveries. Something like that is difficult to prove. sure you can take a gay man and prove that his patterns and sexual reactions are different, but in order to prove it, you have to follow him along with a hetero test subject from birth to follow the development of a brain pattern. And since there's no way to tell if someone's gay until they know, there's no way to avoid contaminating the test and making it unbiased.

    People discover thier own sexuality through a process of learning and behavior by example. If people are "born that way" then how do you explain extreme instances of sexual deviance? You would have to acknowledge that they also, are "born that way", and that it is a function of genetics. So any type of "fetish" or sexual preferance, including hermaphrodites, transexuals, and others would have to be included in this premise. People's choices in these areas are influenced by surrounding environmental factors and learned behavior, not by genetics.
  16. Jul 7, 2003 #15
    Re: Re: Re: is everything predictable?

    1) What about my male dog's attraction to female dogs? Is that instinct (biologically based) or is it learned from him watching other dogs?

    2) If it's biological, then it stands to reason that if the dog is behaving differently, then that may also be biological. Indeed, we find about the same percentage of homosexual activity in the animal world as we do in humans.

    3) If you say "people aren't animals", then you may be right to an extent. We do have the ability to learn and our behavior does have a wide variety of complex reasons behind it. Nevertheless, we also still have a lower "animal" brain with instinctive urges.

    4) That being the case, do you think it was just cultural happenstance that men have learned to be attracted to women and vice versa? If so, that's a convenient cultural coincidence that really worked out for our reproductive benefit don't you think?

    5) But since we know that men's attraction to women and vice versa DOES have a biological instinctive basis, then it stands to reason that, just as there are a minoity of people who vary in all sorts of biochemical and hormonal ways, there would be a minority who do not have such an instinct, or have the opposite.

    When it comes down to it, you cannot claim that a homosexual's attraction to the same gender is not biologically based, unless you also say that your attraction to the opposite gender is not driven by biology as well.

    If your ascertion were correct, then the presence of homosexuality would not be a constant over centuries and over different cultures, and would not be observable in all species in about the same proportions.

    Now, certainly, humans - having more complex brains, have a number of different factors making up their behavior, and people can be swayed by learned behavior to act differently than their base instinct would urge them. Just as you could take a heterosexual and twist him into anything you wanted by putting him in a world condemning his urges and conditioning him, the same could be done to a homosexual. This is no different than conditioning a person to vomit when they smelled potatoes. But that doesn't mean that we don't have natural instinctive drives and it simply doesn't make sense to think that the drive of homosexuals is not instinctive but the drive of heterosexuals is. Only someone who has been "conditioned" by their society to think of homosexuality as wrong or unnatural would not be able to plainly see this, hehe.

    It's this sort of silly view about homosexuality that leads people to fear that it will "threaten the family". As if they're going to "turn everyone gay", assimilating them like the borg - utterly ridiculous. There will be however many gays there will be - period. The only question is if they're going to live among us as equals or be treated as a permanent underclass. And families will get along just fine. Some seem to think that the only reason people form into families is because of government programs and tax incentives. Families form because that's what the majority of human beings have an instinctive urge to do. It would happen even if you had active government effort to stomp families out by force. So, just as it's silly to think that families are endangered just because we're not oppressing gays into living falsely as heterosexuals, it's also silly to think the government can "save the family" by programs and incentives.
  17. Jul 7, 2003 #16
    in short...yes

    check some other threads about randome they are in mathmatics and either philosphy or religion
  18. Jul 8, 2003 #17
    But what about Quantum Uncertainty? While it's probabilities are calculable by mathematics, it is never possible to determine it's actual state.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Is everything predictable?
  1. The theory of everything (Replies: 61)

  2. The Theory of Everything (Replies: 20)

  3. IQ is everything? (Replies: 32)