Always 50/50 chance?

[Hammer_of_Thor]

I have a math question.

Is anything not a 50/50 chance of being true, right, or correct?

As an atheist I believe that there is no god but there may be. There is a 50/50 chance that god exists though. As with anything else. I will either wake up tomorrow or I wont. See how it goes

My thinking may be over simple so I ask for some help in working through this.

Thanks

 

[RecoveringYuppy]

The odds on all unpredictable events can't be 50/50. You run in to a contradiction very quickly if you try to apply that. The odds against you waking up tomorrow morning are only 50/50? And the odds against you waking up a week from now are onlly 50/50? Can't both be true. There's seven mornings between now and next week, multiply it all out and you have a 99+% chance of being dead next week.

Unknowable yes/no questions are not automatically 50/50.

 

[Rasmus]

If you had a 50/50 chance of waking up tomorrow, and the day after that, and the one after that, etc. then anyone's chances of being alive next week are 1:0.0078125 or (1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2)

That means that most people you know would be dead by next week (never mind the amazing coincidence that they all lived as long as they did!) Better say your goodbyes now. Half of them won't be there tomorrow.

 

[Marquis de Carabas]

You have a 6-sided die.

You toss it. You will either roll a one or you will not roll a one.

Therefore, you have a 50% chance of rolling a one.

The same is true for all other values on the die.

As such, every time you roll a die, there is a 300% chance you will get some number.

 

[LawnOven]

Hmm, your understanding of statistics and data are flawed.

 

[drkitten]

I have a math question.

Is anything not a 50/50 chance of being true, right, or correct?

Almost everything isn't 50/50. Roll a die -- your chance of getting a 6 is about 17%, not 50%. Your chance of not getting a 6 is about 83%. Your chance of rolling a perfect square is about 33%.

Flip five coins. Your chance of getting at least one 'heads' is about 31/32, close to 97%. Your chance of getting all tails is a miniscule 3%.

Draw a card out of a deck of cards. Your chance of getting a spade is about 25%, slightly less if you've kept the jokers in. Your chance or drawing a queen is about 8%. Your chance of drawing the queen of spades is about 2%.

If you doubt any of these probabilities, head to a local casino and tell me how the odds can simultaneously be 50/50 on getting red, black, or green at the roulette wheel.....

 

[Oualawouzou]

The way I see it, the questions you gave as example give the illusion they are 50/50 chances occurances, but they're not.

Quick rundown:

Is there a God?

-God is a man-made concept (you don't see animals worshipping, and deities take different shapes depending on the society that crafts them). Thus, if a god exists, then it means some humans somewhere know the Truth and can demonstrate it.
-No iteration of God has ever been demonstrated to exist by humans after several thousand years of worship in various forms.
-Therefore, the chances of God being a man-made concept derived from some actual reality is next to nil. The chances of God being a man-made concept based on a variety of other things (need to find an explanation for some phenomenons, tool to assert control over society, etc.) are very high as these claims can be demonstrated and run afoul the idea that God, in the way religion use the term, exists.

Therefore, the probability of God existing isn't 50%.

Obviously, that was done on the fly from the top of my head, but I think it illustrates the point well.

 

[Hammer_of_Thor]

All of these answers are good.
I am asking about a single event. When flipping a coin I will either get heads or tails, when picking a card I will either get a red or black. When I roll a die I will either roll a 4 (or whatever number) or I wont.

I appreciate all the help here. I really want to understand.

 

[IXP]

If the odds of any proposition was 50/50 statistics would be a whole lot easier. So no.

IXP

 

[Hammer_of_Thor]

If the odds of any proposition was 50/50 statistics would be a whole lot easier. So no.

IXP

Really? Can you give me an example of a single event that does not have a 50/50 chance of happening?

I understand the odds of many things happening, like flipping 6 heads in a row, but with a single event there is a 50/50 chance of that happening. Right?

 

[Drudgewire]

Really? Can you give me an example of a single event that does not have a 50/50 chance of happening?

I understand the odds of many things happening, like flipping 6 heads in a row, but with a single event there is a 50/50 chance of that happening. Right?

I can either walk outside my door and be struck by lightning or not be struck by lightning.

Doesn't mean there's a 50% chance I'm about to be fried to a crisp.

 

[GreedyAlgorithm]

All of these answers are good.
I am asking about a single event. When flipping a coin I will either get heads or tails, when picking a card I will either get a red or black. When I roll a die I will either roll a 4 (or whatever number) or I wont.

I appreciate all the help here. I really want to understand.

You may be referring to (or have independently nearly arrived at) the Principle of Indifference. If you're not a commie frequentist , then you will need to assign prior probabilities to events. Indifference says that if you have no relevant knowledge whatsoever about N events, you should assign them all probability 1/N of occurring. A good way to tell if you have no information is to rename the events. If nothing changes in the way you think about them, assume they're equally likely. For example, you can rename red to black and black to red and nothing changes about picking the card, but if you renamed 4 to 1,2,3,5,6 and 1,2,3,5,6 to 4 the way you look at the events changes.

 

[Marquis de Carabas]

Really? Can you give me an example of a single event that does not have a 50/50 chance of happening?

I understand the odds of many things happening, like flipping 6 heads in a row, but with a single event there is a 50/50 chance of that happening. Right?

If you honestly believed this--I mean deep-down unreservedly held it to be true--I have no idea how you could live without being in a constant state of fear. Walk outside, there's a 50% chance you'll get struck by lightning. Take a bite of that hamburger, there's a 50% chance you choke. Start your car, there's a 50% chance some nutjob has wired it to explode upon ignition.

You may be the bravest person who ever lived.

ETA: There was a 50% chance someone else would come up with the same lightning example, and Drudge nailed it.

 

[pgwenthold]

Really? Can you give me an example of a single event that does not have a 50/50 chance of happening?

You mentioned one in your post before this one.

You roll a die and you either get a 4 or you don't. The chance of getting a 4 is 17%, not 50/50.

 

[GreedyAlgorithm]

Really? Can you give me an example of a single event that does not have a 50/50 chance of happening?

I understand the odds of many things happening, like flipping 6 heads in a row, but with a single event there is a 50/50 chance of that happening. Right?

There is no reason to say flipping 6 heads in a row is necessarily more than 1 event or exactly 1 event, it's all in what you're modeling. Do you think "flipping a single coin" is a single event? Why isn't it "the probability your flip has X, Y, or Z force behind it and the probability you give the coin A, B, or C angular momentum and the probability that a bird does or does not snatch it out of the air, dropping it a moment afterward and the probability that the coin is or is not buffeted by the sudden gust of win etc".

 

[Drudgewire]

ETA: There was a 50% chance someone else would come up with the same lightning example, and Drudge nailed it.

Conversely, there was a .0001% chance that I'd ever be the first person to make an analogy that was correct in a science and math forum.

 

[Hammer_of_Thor]

Doesn't mean there's a 50% chance I'm about to be fried to a crisp.

Thank you for this post and all the posts. I am flawed in thinking that whether or not something will happen is the same as a 50% chance of it happening. This is not correct.

I thank you all for the help. That is why I posted here. Lots of very intelligent people to help me through my flawed thinking.

Thanks to all,
Hammer

 

[Hammer_of_Thor]

I came here to learn and that I do on a daily basis.

 

[JoeTheJuggler]

Really? Can you give me an example of a single event that does not have a 50/50 chance of happening?

Several people have already done so.

I understand the odds of many things happening, like flipping 6 heads in a row, but with a single event there is a 50/50 chance of that happening. Right?

Wrong.

You obviously don't understand probability. Just because you can always define events as two states, doesn't mean the probability of one is equal to the other.

On a normal die, the chance of any particular number coming up (like a 4, say) is 1:6 (because of the 6 sides, only one of them is a 4--in other words, there's a 1 out of 6 chance). If you prefer percentages (as in your 50/50 which is 1:2 like the odds for heads on a normal coin toss), the chance of a 4 coming up or not is about 16.7 / 83.3.

What that means is there is a 16.7% chance you'll roll a 4, and a 83.3% chance that you'll roll a 1, 2, 3, 5 or 6 (i.e. not a 4).

The question I think you're driving at is, "Is it right to assume even probability for the existence of an unknown such as God?" The answer is still no. If the definition of God can be proven to be logically inconsistent (self contradictory) or in contradiction of other known facts, then its probability of existence is zero.

So the probability of the existence of a 2 ton, massless elephant is also zero. The probability of a circle whose circumference to diameter ratio is 4 is also zero.

 

[fls]

All of these answers are good.
I am asking about a single event. When flipping a coin I will either get heads or tails, when picking a card I will either get a red or black. When I roll a die I will either roll a 4 (or whatever number) or I wont.

I appreciate all the help here. I really want to understand.

Let's take your last example. When I roll a die, I will either roll a 4 or I won't - so your two events are "I will roll a 4" or "I won't roll a 4". The "or" tells you that the probability of the two events will sum to 1, but the probability of each event is determined separately. The probability of "I will roll a 4" is 1/6 and the probability of "I won't roll a 4" is 5/6.

Probability can be thought of as a frequency - the number of times a particular outcome can occur divided by the the total number of possible outcomes. When you roll a die, it will show one number face up. That number will be a 1 or 2 or 3 or 4 or 5 or 6, so there are six possible outcomes. The number of times that it will be a 4 is once, so the probability of a 4 is 1/6.

You need to step back and when you find yourself saying "this" or "that", figure out "this" in isolation from "that".

Linda