Monday, March 3, 2014

Linda is a...

Consider the following scenario:
Linda is thirty-one years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in antinuclear demonstrations.
Now, which alternative is more probable?
1. Linda is a bank teller, or
2. Linda is a bank teller and is active in the feminist movement.
If you chose 2, you just committed the "conjunction" fallacy.  To read why, and to learn about 9 other very common, very powerful logical fallacies, click here.  My favorite: the "sunk cost" fallacy, primarily because it was the subject of my PhD dissertation (in psychology, the sunk cost effect is typically referred to as the "escalating commitment" phenomena).