# 5 Minute Philosopher – Probability

One of the central debates in Philosophy is the issue of Probability; in the 18th century British Philosopher Bishop Butler said ‘Probability is the very guide of life’.  Considering that thought it is easy to see why he said it.  When driving we expect a high probability that when we put our foot on the brake the car will slow down, or when we dial a number we get through to the person we wish to speak to.  These two examples do not rely on probability alone; there is also the influence of engineered systems.  Gambling is a situation where probability is not influenced by external systems, or at least we hope not.  In 17th century France Pascal and Fermat studied gambling to better understand probability and the chances of winning.  Be that the toss of a coin, roll of the dice or the turn of the roulette wheel people around the world assign probabilities to the outcome, often with little scientific basis.  Let’s take roulette as an example.  There are 36 pockets on a roulette wheel, so if one bets on a single there are 36 possibilities, resulting in a one in 36 chance of winning.  This is known as the classical interpretation of probability.  Notice I am using two words that are similar, but not the same, possibility and probability.  In the above example there are both a 1 in 36 possibility and a 1 in 36 probability of the ball ending in the number 36 pocket.  Now if we consider this same issue from a different standpoint, that is there are 2 possibilities, either it will come up ass 36 or it will not, the probability has not changed but the possibility has gone from 1 in 36 to 1 in 2.  The 18th century French thinker La-Plasse saw this as a problem with the Classical interpretation so came up with the notion that the cases have to be equally possible to be equally probable, a bit like stating the obvious, but does serve to highlight the need for clarity when considering the notions of possibility and probability.  If we go back to the roulette wheel there is something called the Monte Carlo, or Gambler’s Fallacy, this is where a punter puts money on a particular number and when it does not win puts more money on the same number in the belief that as it has not come up all night it’s time is due.  In fact at each spin of the wheel there is that same 1 in 36 chance or probability of it coming up.

Much of scientific research is based on probability.  If one conducts an experiment and gets a certain outcome it could be speculated that it will always be the outcome of such an experiment.  However, it is only when the experiment is repeated with the same result can we assign a degree of probability.  The more times the result is repeated without fail the higher the degree of probability is attributed to this experiment.  There can never be 100% certainty on the outcome, no matter how many times the experiment is repeated, only a higher degree of predictability.  This issue is seized upon by climate change deniers who often say the science is not conclusive because the scientists will not give a 100% degree of certainty, but that is not the scientific way.

I will finish with 2 examples of the folly of turning probability into certainty.  They both relate to expectations built on repeated consistent experiences.  The first is now the focus of a book called black swans.  When the European explorers arrived in WA they had seen thousands of swans, and believed all swans were white, based on a wealth of personal experiences.  They were staggered to find the swans in WA are black, in contrast to everything they believed.  The book uses this as a parable for us to never to rule out alternatives to our personal experiences, no matter how often they have been reinforced.  The second is a seasonal and cautionary tale I once heard called the Engels existential turkey.  Every morning a turkey goes to the farmer’s door and gets a handful of grain.  This happens once, ten times, a hundred times, The turkey has built up a huge amount of anecdotal evidence to expect each time it goes to the farmers door it will get fed, on the 365th day the farmer chopped of its head with an axe.  Have a great Christmas!

### 2 Responses to 5 Minute Philosopher – Probability

1. jolly says:

HI Jon, nice piece!! Just out of interest are the swans on the Freo train station entrance still whlte? In light of the black swan take above, can the council paint them black- as surely that’s what they were!? Best, Jolly

• jonstrachan says:

Hi Jolly, Thanks for reading a bit of history. The State Gov did a great job renovating the railway station. I guess you remember the debate on the colour of the swans. And yes, they are still white. Look out for the swans on the Town Hall when it is unveiled soon!