It was misleading for James to tell the Core Curriculum Committee that the chair of the Anthropology Department had endorsed his proposal. The chair of the Anthropology Department had told James that his proposal had her endorsement, but only if the draft proposal she saw included all the recommendations James would ultimately make to the Core Curriculum Committee.
The assumption that the draft proposal that the chair of the Anthropology Department had seen did not include all of the recommendations in James's proposal to the Core Curriculum Committee is required by the argument.