People with mental health problems are almost never dangerous. In fact, they are more likely to be the victims than the perpetrators. At the same time, mental illness has been the common denominator in one act of mass violence after another.
A treatment method or an educational method that will work for one child may not work for another child. The one common denominator for all of the young children is that early intervention does work, and it seems to improve the prognosis.
Among those whom I like or admire, I can find no common denominator, but among those whom I love, I can: all of them make me laugh.
I'm an anarchist. I'm implacably opposed to heirarchical systems of power and control. I also mistrust crowds, as they often operate according to their lowest common denominator. In terms of evolutionary psychology, the crowd is very close to a herd of stampeding wildebeest.
One common denominator of super-affluent alpha men is the conviction, unchallenged every day, that the world revolves around them.