De Man's point is a question is both rhetorical and grammatical, and the one cannot be reduced to the other. Both readings are available.

德曼想指出的是，一个问句既是修辞型问句又是语法型问句，那么一个不能变成另一个，两种理解都有效。

耶鲁公开课 - 文学理论导论课程节选

or you can turn it into a question, and ask "Is there" to ask the existence of something.

当然你也可以把它变成一个问句，用“Is there”来询问某些事物是否存在。

There is 课堂 - SpeakingMax英语口语达人

Also you can use the "There is" statement, to be a question by inverting it.

你也可以使用“There is”句型，将陈述句转换一下就可以变成问句。

There is 课堂 - SpeakingMax英语口语达人