In this week's New Scientist (New Scientist, April 19, 2008) there is a brief column entitled "Moon's birth put Earth in a spin" that includes this sentence:
The moon is widely thought to have formed after an object roughly the size of Mars crashed into the Earth 4.5 billion years ago, throwing up a cloud of debris that eventually coalesced into a rocky sphere.
I don't disagree with this at all. I am peripherally aware of a couple of moon formation theories. I probably could have told you that impact plus debris ejection was a favourite. My question: when is it correct to say that something is "widely thought" in science? Equally, how would one challenge this assertion?
Thesis: a certain absolute number and proportion of relevant scientists, as well as a ranking among competing theories are all necessary, but not sufficient to say that a view is widely held.
Example: If a view is held by less than 20% of relevant scientists in a field, less than a dozen scientists in total, is less popular than two other theories or is less than half as popular as the dominant theory, it is not widely held.
If anyone who reads this thinks that my hypothetical numbers could be improved, can think of another factor that would determine whether a view was widely held or not, or would like to leave some random abuse - please do so! Abuse will be deleted though. Unless it's funny.