On the use of common sense in science

Common Sense

“If common sense was a reliable guide, we wouldn’t need science in the first place.”

A.Gefter, New Scientist

I have noted that on this blog, the expressions “it’s common sense”, “it’s obvious”, “it’s natural” are widely diffused, and are not often based on realities.

Apart from the fact that there are things that seem obvious for some people but not for others, the goal of this small article is to show you a few illogical but true examples, and that Common Sense is something really fuzzy. We’ll find that the further we go into the “exactness” of the science fields, the more unreasonable it gets.

And I thought I was walking with Angels…

From the April 2010 Scientific American Magazine

The Sensed-Presence Effect

How the brain produces the sense of someone present when no one is there

By Michael Shermer

Photo: Matt Collins

In the 1922 poem The Waste Land, T. S. Eliot writes, cryptically: Who is the third who always walks beside you?/When I count, there are only you and I together /But when I look ahead up the white road/There is always another one walking beside you.

In his footnotes to this verse, Eliot explained that the lines “were stimulated by the account of one of the Antarctic expeditions [Ernest Shackleton’s] … that the party of explorers, at the extremity of their strength, had the constant delusion that there was one more member than could actually be counted.”

Third man, angel, alien or deity—all are sensed presences, so I call this the sensed-presence effect. In his gripping book, The Third Man Factor (Penguin, 2009), John Geiger documents the effect in mountain climbers, solo sailors and ultraendurance athletes. He lists conditions associated with it: monotony, darkness, barren landscapes, isolation, cold, injury, dehydration, hunger, fatigue and fear. I would add sleep deprivation;