A, B and C are discussing about randomness. Person A asks person B," What is the probability of obtaining head when you flip an unbiased coin?" Person B says, "If the flip results in head the probability of head is 1, else it is 0." A and C start laughing on this. But suddenly C changes side and says that he supports B. In-fact, C says that the coin flip is not at all random. C says that we can predict the result of a flip if we know enough information - height of the coin from ground, amount of force applied to the coin, the point where the force is applied and so on. Now A got C's point. Then A asks, "Why do we say that there is 1/2 chance of obtaining head?" To this C replies, "There is no way to find out that the probability of flip is indeed 1/2." A crazy scientist once decided to prove that the probability of head from a flip is 1/2 and he kept on flipping the coin all his life but was never able to prove this.
Laplace never believed in randomness. Here is something directly taken from wikipedia:
Laplace strongly believed in causal determinism, which is expressed in the following quotation from the 'Introduction to the Essai':
"We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect (Laplace's-Daemon) which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes."
The quotation challenges everyone who talks in terms of probability. Let me give some examples where probability may or may not be a useful way to think about scenarios:
1. "There is a 70% chance that India will win"
Now realize that Laplace's Daemon would know every thing required to predict India's fortune. He will know what are the mental, physical, psychological and spiritual states of all player, umpires, referees and audience. He will know ground conditions, weather forecast and so on. He can indeed say that at the end of the day whether India is going to win or loose. However, predicting India's fortune is very hard for even Laplace daemon because the amount of computation power he may require could be huge.
2. "There is a 90% chance that the bus will not arrive at the stop on time"
Now, amount of information required to predict whether the bus is going to come late is not huge. You may just have to call the bus station people, see weather forecast or even now a days a real time monitoring of status of buses is possible. So, if some one tries to use the probabilistic statement for making a decision, as to when the bus is going to arrive on the bus stop, he is not making a wise choice.
3. "There is a 70% chance that I will be late tomorrow for office"
Now this statement is totally absurd. People are so occupied with probability that they consider themselves to be unpredictable.
The three examples that I talked about have a salient gradation among them. In example 1 the problem of prediction was hard. In example 2 it was not so hard. In example 3 it was very simple.
Conclusions: At time saying things in probabilistic terms may sound smart at the outset, but can be totally stupid or absurd in the core. I personally think that prediction by probability should be avoided if possible for the simple reason that there is not a very foolproof way to estimate probabilities. Even if there were a foolproof way, probabilities can only make predictions which are probabilistic. It may so happen today that the bus arrives at bus stop early even though it was 90% probable that the bus is going to come late.
Subscribe to:
Post Comments (Atom)
nice!
ReplyDeletea non-believer :)
I think this:
ReplyDeleteFor something to be perfectly random it should have an infinite number of factors influencing it. And then I feel the question boils down to: is infinity real?
Infinity is such a mysterious concept. Mathematicians use it in abstract sense and simplify their analysis by taking limits or somehow using the idea of unboundedness. I think that most of the things in this world are affected by a huge number (possibly infitely many) of factors. But in most cases one can find important factors easily. These important factors are the ones which are relevant for the prediction that we intend to make. Certainly if the number of these important and relevant factors becomes infinite the outcome that we want to predict is likely to be random. There is a possibility that these infinitely many relevant factors can be mapped to a few factors in some way that these few factors can make the deterministic prediction possible.
ReplyDeleteI have read this one somewhere that the important relevant factors can have following four forms:
1. Known knowns
2. Known unknowns
3. Unknown knowns
4. Unknown unknowns
I think the presence of 'unknown unknowns' is what will certainly make the outcome random.
Thought provoking.
ReplyDeleteHowever the question then becomes: what is the count of unknown unknowns?
Since the number of unknown unknowns will remain unknown for an undefined period of time, the outcome will remain a mystery. So maybe then it should should be labeled something other than random; random with a funtion of time?
To expound that further:
ReplyDeleteAt time x the unknown unknowns will transform into known unknowns i.e Option (2).
I think option (3) just tells us that more investigation can give the answers.
Perceptive!
ReplyDeleteI think that Science is all about reducing the number of 'unknown unknowns'. People observe things repeatedly and at the end of some observations they discover some new factors which were among 'unknown unknowns' for a long period of time. Then these new factors move into the category of 'known unknowns' or 'unknown knowns'. Now a lot of work has to be done to move the new factors from these two categories into the category of 'known knowns' which is were we want all our factors to be.
So yes, scientific progress is indeed reducing the randomness in this world. e.g. The cause of 1918 bird flue pandemic were unknown in 1918, that is why people thought that 'yeh bhagwan ka prakop hai'(random outcome). However the cause (Influenza virus) is known today. I agree with your conclusion that random things may not remain random as time progresses.
You have brought out the crux of the post which I think is:
'Probability is a escape way of not dealing with the situations by scientific methods.'
Yes, exactly! :)
ReplyDelete