Not that I know of: a polarity-sensitive construction

The paper discusses hedges such as that I know of in The train is not late, that I know of, which form a hitherto undocumented polarity sensitive construction that can be found in a number of European languages. Internally, they resist negation, in ways reminiscent of parenthetical as-clauses, and other parenthetical constructions. On the basis of a small corpus of English and Dutch occurrences of the hedge construction, I outline the distributional properties and internal structure. A number of restrictions are uncovered regarding the subject of the hedge clause (in particular: universally quantified and indefinite subjects are ruled out, second person subjects are limited to questions), which point to a strong pragmatic effect of point of view, but still require further study. The polarity sensitive status of the hedge is derived from the interaction of strong verbs (know, be aware of, etc.) and the pragmatic requirement of hedges that they tone down a statement. Together, these require that the hedge be within the scope of negation.