I find it very hard to come to any firm conclusion about whether the inclusion should be based on self-identification or factual criteria without knowing what purpose the list serves, although, like most others here, I am drawn to using factual criteria.  I think it is best to use whatever makes it clearest who belongs and who does not.  Using self-identification would not have solved any of the current arguments.  My only real concern is that this list is not used to promote a pro or anti vegan POV.  At the present, as Len points out, we accept either a source saying that the person is a vegan, or saying that the persons says that they are a vegan, or that they adhere to a vegan diet.    This seems to lend itself too easily to being used as a promotional vehicle for veganism.  Only adding those for whom we can find a source saying that a person adheres to a vegan diet, as I think Len is suggesting, is a bit too restrictive, in my opinion.   

I think