Abdolhossein  Zarrinkoob is one of the prolific Iranian writers and historians in modern times. He has written on a wide range of topics in various fields. Degenerative thought is one of the most important aspects of his writings. Influenced by the intellectuals of Nasserite historians and modernist theorists of the Reza Shah period, he addressed the factors affecting the decline of Iranian-Islamic civilization. In comparing the periods of Iranian history, Zarrinkoob not only reproduced the explanations of his predecessors but also added other elements to them. Accordingly, one of his most important efforts to get out of this degenerate state was reminding the issue of degeneration. By raising this issue, he addressed the historical decline of Iran and Islamic civilization based on a historical approach. The findings of this study, show degeneration comprises some elements such as pro-Greeks, determinism, and anti-rationalism. He, based on the analytical-descriptive method, argues that we should pay attention to religion, materialism, tolerance, freedom of thought, and good relations with other nations. He believes that rationality is important for the politicians of today's Iranian society, and adds that ignoring these characteristics is tragic. In this sense, his focus is on solving the problem of degeneration in pre-modern and contemporary Iran, recreating and perpetuating the cultural and ethnic elements that remained from the historical past.

Keywords: Islam, Decline, Iran, Anti-rationalism, Determinism, Pro-Greeks