Submitted by Reason-Local t3_11de5ag in explainlikeimfive
RedFiveIron t1_ja9g8f3 wrote
Reply to comment by johrnjohrn in ELI5: why does/doesn’t probability increase when done multiple times? by Reason-Local
You're constructing an extremely unlikely scenario to rationalize thinking a die has memory. It does not.
The previous results don't affect future outcomes for a fair die, no matter what those previous results are or how unlikely that outcome was.
Let me toss that back at you: How many unlikely outcomes have to occur before it "begins to matter"? Is one enough to start ignoring the math? Ten? A thousand?
johrnjohrn t1_ja9qjlw wrote
I never offered that the die has memory. I only offered a hypothetical in which a fair die rolled one quintillion times on the same number by what a mathematician would say is pure chance. And your suggestion that I believe that implies that you have some inherent belief that the math "breaks down" at some undefined, seemingly ridiculous point. Regardless of the number of rolls I pick, you will say it doesn't matter and I say at some point it does. That is the rub. You have absolute confidence that any limitless number I can think of wouldn't sway you into reconsidering which number would be most "rational" to pick next if this all occurred in front of your eyes.
I think what I'm really saying is that normally we'd expect, on average, a die that may roll the same number that can be explained with mathematical probabilities. And those probabilistic averages play out the same, all day every day in casinos everywhere, because we observe them, and the laws of physics appear fixed. Any gambler who thinks those laws of physics and probabilities will change based on their crude observations of a small number of rolls is, in fact, a fool.
Now, you suddenly have an outlier that outlies averages so far that the whole casino industry topples because of it. Although my scenario is absurdly unlikely, your math shows that it is equally possible, albeit unequally probable. Is the gambler who watches the seemingly supernatural phenomenon unfold in real time all that foolish if they were to bet on the next outcome to be the same as the prior quintillion?
I suppose this might be a question of philosophy and not math. And I'm not arguing with the defined math, but I firmly stand beside the point that eventually it is not irrational to assume the same number might be rolled one more time after observing it a quintillion times.
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