## Gambler's Fallacy
- The Monte Carlo Fallacy
- The Doctrine of the Maturity of Chances
## Form:A fair gambling device has produced a "run"―that is, a series of similar results, such as a series of heads produced by flipping a coin.
## Example:On August 18, 1913, at the casino in Monte Carlo, black came up a record twenty-six times in succession [in roulette]. … [There] was a near-panicky rush to bet on red, beginning about the time black had come up a phenomenal fifteen times. In application of the maturity [of chances] doctrine, players doubled and tripled their stakes, this doctrine leading them to believe after black came up the twentieth time that there was not a chance in a million of another repeat. In the end the unusual run enriched the Casino by some millions of francs.
## Exposition:The Gambler's Fallacy and its sibling, the Hot Hand Fallacy, have two distinctions that can be claimed of no other fallacies: - They have built a city in the desert: Las Vegas.
- They are the economic mainstay of Monaco, an entire, albeit tiny, country, from which we get the alias "Monte Carlo" fallacy.
Both fallacies are based on the same mistake, namely, a failure to understand statistical independence. Two events are statistically independent when the occurrence of one has no statistical effect upon the occurrence of the other. Statistical independence is connected to the notion of randomness in the following way: what makes a sequence random is that its members are statistically independent of each other. For instance, a list of random numbers is such that one cannot predict better than chance any member of the list based upon a knowledge of the other list members. To understand statistical independence, try the following experiment. Predict the next member of each of the two following sequences: 2, 3, 5, 7, __
The first is the beginning of the sequence of prime numbers. The second is a random sequence gathered from the last digits of the first four numbers in a phone book. The first sequence is non-random, and predictable if one knows the way that it is generated. The second sequence is random and unpredictable—unless, of course, you look in the phone book, but that is not Many gambling games are based upon randomly-generated, statistically independent sequences, such as the series of numbers generated by a roulette wheel, or by throws of unloaded dice. A fair coin produces a random sequence of "heads" or "tails", that is, each flip of the coin is statistically independent of all the other flips. This is what is meant by saying that the coin is "fair", namely, that it is not biased in such a way as to produce a predictable sequence. Consider the Example: If the roulette wheel at the Casino was fair, then the probability of the ball landing on black was a little less than one-half on any given turn of the wheel. Also, since the wheel is fair, the colors that come up are statistically independent of one another, thus no matter how many times the ball has fallen on black, the probability is still the same. If it were possible to predict one color from others, then the wheel would not be a good randomizer. Remember that neither a roulette wheel nor the ball has a memory. Every gambling "system" is based on this fallacy, or its Sibling. Any gambler who thinks that he can record the results of a roulette wheel, or the throws at a craps table, or lotto numbers, and use this information to predict future outcomes is probably committing some form of the gambler's fallacy.
## Source:A. R. Lacey, Dictionary of Philosophy (Third Revised Edition), (Barnes & Noble, 1996). ## Resources:- Colin Bruce, "The Case of the Gambling Nobleman", in Conned Again, Watson! Cautionary Tales of Logic, Math, and Probability (Perseus, 2002). This is a Sherlock Holmes short story which explains clearly and entertainingly why the Gambler's Fallacy is fallacious.
- Robert Todd Carroll, "The Gambler's Fallacy", Skeptic's Dictionary.
## Where's the harm?:From a tax court decision: "In 1991, [the gambler] won approximately $26,660,000 from the California lottery…. [He] elected to receive payment of the lottery proceeds in 20 annual payments of approximately $1,333,000 each…. Since winning the lottery proceeds, [he] has not been employed. Why did he behave in this mind-boggling and tragic way? According to a psychologist called as an expert witness: "…[The expert witness] testified that, unlike recreational and problem gamblers, pathological gamblers take the 'gambler’s fallacy' to a delusional level―they believe if they gamble long enough, they will win back all their losses and even more. [The expert witness] also opined that, unless treated for his illness, [the gambler] will gamble until he dies or loses all his money." (P. 26) Here's a note of warning for future litigants: "Respondent attempted to discredit [the expert witness] by claiming her definition of 'gambler’s fallacy' was incorrect. Respondent relies on a definition of 'gambler’s fallacy' he obtained from Wikipedia. Respondent did not call any witness, or expert witness, to counter [the expert witness]’s conclusions. Respondent’s reliance on a definition of 'gambler’s fallacy' found in Wikipedia is not persuasive. [The expert witness]…credibly explained that there is a difference in the definition of 'gambler’s fallacy' depending on the field of study―e.g., psychology versus mathematics. We find [the expert witness] to be credible and rely on her expert opinion." (P. 26) The Respondent should've cited The Fallacy Files, instead! If there really is a difference in the definition of "the gambler's fallacy" in psychology as opposed to math, I haven't heard of it, but I'm no psychologist. The Wikipedia entry for the fallacy at the time of the decision is actually reasonably accurate, but the judge couldn't be expected to know that, which is why he was right not to rely on it.
## Q&A:
―David A. Ventimiglia
An approximately fair gambling device has produced a "run".
There was a famous "man who broke the bank at Monte Carlo" who studied the roulette wheels in the casino and discovered that one seemed to favor certain numbers. By betting those numbers, the man was able to amass a small fortune. When the casino realized what he was doing, it switched the roulette wheels around at night while the casino was closed, and the man began to lose heavily. Nowadays, you can bet that casinos around the world have learned the lesson, which is why there has been no "man who broke the bank" since the 19th century. However, consider how the man who broke the bank reasoned: Certain numbers on the wheel had come up more often than expected. Therefore, the man bet on those numbers! According to the Gambler's Fallacy, he should have bet In cases such as the Monte Carlo one, it may be reasonable to conclude that a gambling device is not fair based upon a highly improbable series of results. In those rare cases, the Hot Hand form of argument is not fallacious. The Gambler's Fallacy, in contrast, always is.
Gambling Fallacies can be found not only in casino games but other games as well - Bingo for example. We think that we can calculate the odds of the next bingo ball coming out but in bingo, too, it's an impossible mission. try it yourself by playing at *bingonomobile.co.uk* |