Consider the following examples:
Mary is no richer than Jane.
I am sure the book is unpleasant. But it is not all unpleasant and I am sure is no more unpleasant than the real inner lives of some of our best Oak Park families.
Second-hand smoke is no more harmful than bad diet, industrial pollution or stress.
This may be harmful, but at worst it is no more harmful than outright expression of his anger.
The former two could be paraphrased:
Mary is not rich, just as Jane is not.
The book is not unpleasant, just as the real inner lives of some of our best Oak Park families are not.
While the latter two could only be paraphrased:
Second-hand smoke is at least as harmful as bad diet, industrial pollution or stress.
At worst it is just as harmful as outright expression of his anger.
It seems every language has a number of sentence patterns which can convey two opposite meaning.
The question is: can the "no more + adjective + than" construction always be used in either way? Or, it works only for a limited number of adjectives?