The correct answer to this open question is the following.
Unfortunately, you did not attach further references, a text, an excerpt, or something else in order to know Wiebe's argument.
However, trying to help you, we did some deep research and can comment on the following.
Historian Robert H. Weibe published the "Search for Order" in which he commented on the scope of the Progressivist movement and its main reformers. He said that the heart of the progressivist movement relied on the ambition of the middle class to pursue its goals.
One example from the period 1880 to 1920 that could be used to support Wiebe's argument could be the reformer's goal to "clean" the government of corruption reported by muckraker journalists, the modernization of the American education system, and the support of the right of women to vote.
