I changed the whole paragraph to this:
The writer attempts to make a case that the main stream of psychiatric and medical knowledge is wrong.Therefore, the author presents a case that in reality is unfounded because he has no substancial fact to support his claim.
I don't think that the author is claiming that psychiatric and medical knowledge is wrong. He makes the point that there are so many nuances attached to the word "ed" that no one can agree on a suitable synonym.
I suggest that you go back and read your instructions -- especially about the effectiveness of the author's conclusions. Also, two sentences is an awfully short paragraph for a college student.