In the 18th century, a mathematician named Jean le Rond d’Alembert argued (incorrectly, as it was later discovered) that the probability of a tossed coin landing heads up would increase every time the coin landed tails up. From this argument has come the D’Alembert System, a type of martingale betting system, often used when playing roulette. It’s sometimes known as The Monte Carlo Fallacy or the fallacy of the maturity of chances.
According to the D’Alembert System, you add a unit when you lose a spin, and you subtract a unit when you win a spin. For example, if you bet $2 on a spin, and lost, you would bet $3 on the next spin. If you win on that $3 spin, your next bet would go back to the $2 level. Unlike the martingale systems, this doesn’t accelerate your bets so rapidly that you can’t recoup your losses. You continue to play in this manner, until you hit your profit goal, your loss limit, or you get to a bet of $0. In theory, this will insure you losses and bank your profits, so you can get rid of losses more easily if you’ve not been so lucky.
Unfortunately, this system is sometimes called the Monte Carlo Fallacy for a reason; it is based on a flawed argument. According to d’Alembert’s argument, a streak of 20 blacks, for example, would not be likely. However, it is as likely to happen as any other streak; the fallacy of the maturation of chances is just that – a fallacy. Chance is always the ruling factor at the roulette wheel, and any system is, at best, a way to make your betting more methodical. No system in the world can influence the wheel.
If you choose to use the D’Alembert System to help organize your betting, you may have some success with it. In some ways even these technically flawed systems can actually work, the reason is that it instills some discipline in the betting strategy which is what most gamblers lack especially if playing roulette online. If you’re expecting it to change the odds, or influence the wheel, you’re really out of luck. As with any sort of gambling endeavor, do it for fun, and always be aware of your budget and your limits. Enjoy yourself, but do it wisely.