Difference between deep ideas and deep silliness

From The Beginning of Infinity by David Deutsch, in his section responding to John Horgan’s 1996 book, The End of Science: Facing the Limits of Knowledge in the Twilight of the Scientific Age:

“Horgan accepts from the bad philosophy of ‘postmodern’ literary criticism its willful confusion between two kinds of ‘ambiguity’ that exist in philosophy and art. The first is the ‘ambiguity’ of multiple true meanings, either intended by the author or existing because of the reach of the ideas. The second is the ambiguity of deliberate vagueness, confusion, equivocation or self-contradiction. The first is an attribute of deep ideas, the second an attribute of deep silliness. By confusing them, one ascribes to the best art and philosophies the qualities of the worst. Since, in that view, readers, viewers and critics can attribute any meaning they choose to the second kind of ambiguity, bad philosophy declares the same to be true of all knowledge: all meanings are equal and none of them is objectively true. One then has a choice between complete nihilism or regarding all ‘ambiguity’ as a good thing in those fields. Horgan chooses the latter option: he classifies art and philosophy as ‘ironic’ fields, irony being the presence of multiple conflicting meanings in a statement.”