1: There is a reluctance on the part of European companies to buy from American sources.
2: There is an emphasis on the organic roots of spirituality.
3: There is a tendency to make the distinction between 'art' and 'entertainment' too rigid.
4: There is a sense that something about the suggestion is incoherent
I feel there must be more to this than simply "idiomatic preference". What is it about the first two examples that allows (but doesn't require) an article? And that requires an article in the other two?
And are there any similar constructions where the presence/absence of the article affects meaning?