Illustration of Bayes’ theorem

1763 Bayes’ theorem

The book of science

Tom Sharp

Thomas Bayes probability Illustration of Bayes’ theorem

Bayes’ theorem

Intuition disregards the base rate; Bayes taught us to regard it. If you think about whether a mammogram detects breast cancer, you must consider the base rate— the prevalence of breast cancer. If a mammogram shows you have breast cancer and the diagnosis is accurate only 80 percent of the time but only one person in a hundred gets breast cancer, then your chance of having it is only about 7.8 percent.

Bayes’ interpreters

Thomas Bayes was lucky in that after he died, Richard Price became his literary executor, edited his work, wrote an introduction, and presented it to the Royal Society. Pierre-Simon Laplace developed the Bayesian interpretation of probability, unaware of the work of Bayes and Price, so I might have been writing about Laplace’s theorem.


Something funny about the human brain, might be a throwback to an evolutionary stage or a limitation of the structure of its synapses, but it needs training from early childhood, socializing experiences, help from loved ones, continuing stimulation, and constant reminders.

It goes by the name of “logic,” but what we mean is trying to overcome our instinctual thought-processes to adhere more closely to reality.

See also in The book of science:

Readings in wikipedia:

Other readings: