Cui bono

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Qui bono (properly Cui bono?) is Latin for "who benefits?"

It is the single most important question to ask when evaluating any (usually political or criminal) manoeuver. After all, humans are inclined to support, if not cause, actions that benefit themselves.

However, this is not a particularly wise thing to do when answering a question of a scientific or medical nature, as these fields are based in fact and empirical evidence. Special interest groups benefit from scientific advancements, for sure, but the underlying assumption in this case is that everyone else will as well. This has not stopped some from questioning motives anyway. Take Paul Brodeur,Wikipedia[1] who got a significant part of the world afraid that cell phones and power lines cause cancer because people do not understand the difference between ionizing and non-ionizing radiation.[note 1]

Misuse of cui bono[edit]

While it's always good to ask "Cui bono?", it can be taken to ridiculous extremes. One particularly fine example is found in the anti-vaccination movement, where the mundane fact that pharmaceutical companies expect to be paid for the vaccines they produce is somehow blown up into a line of reasoning extending way beyond the sanity horizon: in order to protect the huge profits that they ostensibly make with vaccines, Big Pharma does everything they can to bribe or intimidate scientists, doctors and health officials into silence, because otherwise word would come out that vaccines are Bad, which would of course be bad for profits. Apparently, it doesn't occur to the antivaxxers that simply making good products is far easier, more profitable and rather less risky than selling crappy stuff and then spending absolute fortunes to keep a lid on that indefinitel.

Many other conspiracy theories are also built using this line of reasoning and then work backward from the conclusion by relying on post hoc reasoning. A classic example is 9/11 conspiracy theories. Cui bono? The Bush administration, of course, so they must have done it! Isn't it suspicious that 9/11 just happened to give cover to their plans for war?

Cui bono should also never be the only question to ask, as benefits from an event are never enough to directly implicate one with an action. If it is only asked who benefits from something and other factors are not taken into account, ridiculous conclusions can be extrapolated. Take the following example:

Emperor penguins thrive in extremely cold climates. Many other species don't. Therefore it is obvious that emperor penguins have the most to gain from a cold Antarctica, hence emperor penguins are responsible for the cold in extreme southern latitudes.

It could — and should — have been asked whether emperor penguins even have the means to make it cold in Antarctica, which they obviously don't.

A different example would be the Moon landing hoax theories that get increasingly complicated until landing on the Moon is actually the easier proposition.

See also[edit]


  1. Hint: ionizing starts in the visible light spectrum somewhere around indigo. Radio waves aren't, even when they get up into the hundred-gigahertz range.


  1. The whole sad story is in Voodoo Science: The Road from Foolishness to Fraud by Robert L. Park (2000) Oxford University Press. ISBN 0195135156.