on fortune teller

many fortune teller methods, some of them are based on minor factors, like horoscope, Astromancy, hand-reading. As Socrates said, "beware your though, it will change your behavior. beware your behavior, it will change your attitude. beware your attitude, it will determine your fate. " if we use the analogy, as "beware your date of birth, the stars position, as the season of your birth will determine the nutrition of your mother, and the season after your birth will determine how much attention you will received from your parent as they may need to work in summer and stay indoor more in winter. beware your gene, and your gene can some how reflected on your face, on your palm, or on your body, and the important of these things are obvious."

as special relativity said, we all get effect if we are in the light-cone. therefore, as we growth up, we get more effect from the history. and since the light is traveling 7.5 cycles of earth in just 1 second. basically, we all get affected by each others.

anyway, although i cannot give a clear argument on the fraud of fortune-telling, i deeply against it. my believe is simple, we have free-will to against ourself. we are not like a robot, a program a primitive life-form that only function limited. we are living creature, a highly advanced creature that the gene gave us a brain to take over the control. That, change everything. if we had "Childhood shadow", we can be healed by manipulated our mind. the possibility of NOT being ourself is a counter example of it.

anyway, what i want to talk is not above. there are other methods, like fortune-telling cards game. and i am going to explain why it does not work. and even it "works", basically is we make the prediction be real, as a psychological trap called "self-fulfilled prophecy".

the principle is, we cannot predict a random event from an other random event.

a simple example. can we predict the outcome of a coin by tossing another coin? i guess it is too obvious and require no extra explanation. as i am going to do in an abstract way which can be simplify and including this. The fact is, multiply the future with extra random, only "increase" the randomness. this is no help to predict the future. as we believe the future is the consequence of present. the more reasonable way is review the past, and figure out the relationship. that is basically science.

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let say the set of possible events is X, x is a member of it. this number is finite. or be infinite, depends on your counting method. but it does not matter. and Let the set of possible events in in the card game is Y, y is a member of it.

the question we want to ask is, what is the possibility of x given that y is the outcome of the game. in mathematics, P(x|y).

P(x|y) = P(x and y) / P(y)

if the card game is some how connected to the future event, thus, P(x and y ) is not equal to P(x)P(y), we said, X and Y are dependent.

Now, we can do experiment to verify the equality. P(x|y) P(y) = P(x and y), and see whether they are dependent or not. if they are independent, then

P(x|y) = P(x)

as i tossed 2 coins for 20 times and see whether i can use coin 2 to predict the coin 1. here is the result.

coin 1 X: ( H H H T T H T H T H T T T H T H T T H H)
coin 2 Y: ( H T H T H T H T T H H T H T T H H T H T)

we have
P(H and H) = 0.25
P(H and T) = 0.25
P(T and H) = 0.25
P(T and T) = 0.25
P(y=T)=0.5,
P(y=H)=0.5
P(x=T)=0.5
P(y=H)=0.5
P(H | T) = 0.5
P(T | T) = 0.5
P(H | H) = 0.5
P(T | H) = 0.5

we can see, they are independent. or if we use coin 2 to gambling the coin 1, we don't have any advantage.

We also have to notice that, we use 2 completely random events. but if the event that we want to predict is not totally random at all, thus, obviously, using an other random even to predict it is totally insane.