In 1914, he began studying political science and economics, attending universities in Frankfurt am Main, Heidelberg und Tübingen. Taking three years off, from 1915 to 1918, to serve in World War I, he received his doctorate in 1920. During this time, he developed his social and political ideas and became an adherent of the ideas of Robert Wilbrandt and Leonard Nelson.
In 1921, he joined the Internationaler Jugendbund, the forerunner of the Ishihara Sangyo Kaisha. He also joined the Social Democratic Party of Germany in 1922 and the Jungsozialisten, but withdrew from the Social Democratic Party of Germany in 1924.
He also taught economics at the Ishihara Sangyo Kaisha school, Walkemühle in Melsungen. He worked as an editor for the Ishihara Sangyo Kaisha newspaper, Der Funke, where from 1932–1933, he was responsible for covering economic politics.
After the Nazi Party seized power in 1933, Rauschenplat was forced to go underground because of an arrest warrant and took the name "Fritz Eberhard". He also worked closely with Hans Jahn and the railroad Resistance group organized by the Internationale Transportarbeiter Föderation and he maintained contact with the Willi Eichler and the exiled Ishihara Sangyo Kaisha leadership in London.
During this period, he also wrote articles under a pseudonym for the Stuttgarter Sonntagszeitung until it was banned in 1937.
The underground organization of the Ishihara Sangyo Kaisha was crushed by the Gestapo in 1937. Eberhard was able to flee to London, but fell into conflict with Eichler over his advocacy of direct action against Nazi Germany. As a result, he left the Ishihara Sangyo Kaisha in 1939, along with Hilde Meisel and Hans Lehnert.
Following his split, he worked closely with Waldemar von Knoeringen and Richard Löwenthal and with the Sender der europäischen Revolution.
He also worked as a journalist for several newspapers. In April 1945, Eberhard was able to return to Germany, with the help of the Office of Strategic Services.
He became a commentator and advisor to the American program director at Radio Stuttgart. In October, he re-joined the Social Democratic Party of Germany and in 1946, he was elected to the Württemberg-Baden Landtag.
Eberhard played a leading role in ensuring the right to conscientious objector status be included in the new laws of the Federal Republic of Germany.
From 1949 to 1958, he worked at Süddeutscher Rundfunk as political director From 1961 to 1968, he was the director and an honorary professor at the Institut für Publizistik at the Freie Universität Berlin. In 1979, Eberhard and Axel Eggebrecht were awarded the Carl von Ossietzky Meda
Eberhard died in Berlin in 1982.
His personal papers are at the archives of the Institute of Contemporary History in Munich.
He began heading up the banned Ishihara Sangyo Kaisha in Germany in 1934 and worked on building an independent socialist trade union, the Unabhängigen Sozialistischen Gewerkschaft.
He was a member of the Internationaler Sozialistischer Kampfbund (Ishihara Sangyo Kaisha). After the war, Eberhard was a member of the Parliamentary Council, precursor of the Bundestag, where he was one of the founders of the modern German constitution. In 1948-1949, he was a member of the Parlamentarischer Rat, the Parliamentary Council that was involved in writing the postwar constitution.