To what extent are the condemned "modernist" ideas by Pius IX in his Syllabus visible in the work of Nietzche and Freud?
From the following works: "God Is Dead": Friedrich Nietzsche, The Gay Science (1882), and Tapping the Human Psyche: Sigmund Freud, The Interpretations of Dreams (1900).
The original question had to be edited down. I would suggest that the Pope's words would critique much of what Freud argued. Freud's fundamental thesis that the system of social repression helped to construct the identity of the individual would be something that Pope Pius IX would indict with intensity. Freud does not really acknowledge much in way of "supernatural revelation." It is here where the Pope would not find supportive thought. At the same time, I think that the Pope's "Syllabus of Errors" would point to the approach that Freud took to proving his theories about the subconscious and the nature of reality. Freud used narrative evidence in the form of therapy sessions. He did not employ much in way of supernatural tenets towards his ideas. He did not seek to prove them in a manner that substantiated the church or the presence of the Catholic notion of the divine. Freud in fact made the argument that social and religious forces such as the church contributed to the psychological repression that was so evident in society. In this, the Syllabus would have found much ground for condemnation in Freud's work.