Gertrude Anscombe @ SEP

Some of Anscombe's most influential work was on the nature of causation. The relation between cause and effect has been notoriously difficult to analyze. Anscombe's work in “Causality and Determination” challenged some of the empiricist orthodoxy of Hume's account. For example, she challenged the view that the causal relation is characterized by constant conjunction in discussing Feynman's Geiger counter case:

An example of a non-necessitating cause is mentioned by Feynman: a bomb is connected to a Geiger counter, so that it will go off if the Geiger counter registers a certain reading; whether it will or not is not determined, for it is so placed near some radioactive material that it may or may not register that reading.

And yet, if the bomb explodes it was caused by the Geiger counter arrangement. Causation does not involve determination, or necessity. Since the radioactive decay was not sufficient for this effect, the case tells against viewing causes as sufficient conditions. There is no general causal connection between cause and effect.

From a new entry on Anscombe at the Stanford Encyclopedia of Philosophy.