Final answer:
The Abbasid empire declined due to internal corruption and fragmentation, as well as external threats such as the rise of rival states like the Seljuks. The Ottoman Empire faced similar challenges, including stagnation, technological backwardness, and the military superiority of European powers, culminating in its dissolution after World War I.
Step-by-step explanation:
When comparing the declines of the Abbasid and Ottoman empires, we observe a pattern of internal weaknesses and external pressures leading to their downfall. For the Abbasid Empire, the decline was characterized by the worldliness of their culture, which alienated religious conservatives. Scholars like al-Ghazali criticized the caliphate's engagement with non-Islamic philosophies, especially Greek speculative thought. The adoption of Persian culture and the preferential treatment of Persian families further estranged Arab elites. A sign of internal decay was the entrenched bureaucracy and reliance on mamluks, reflecting the perception of a corrupt administration. The emergence of rival states, such as the Seljuks, and the conception of other caliphates further divided the Islamic realm.
Similarly, the Ottoman Empire, emerging as the successor to the Abbasid as a dominant Muslim power, faced its decline after enjoying an extended period of economic and military dominance. The long-reigning Ottoman sultans saw the erosion of their empire due to stagnation and failure to keep pace with technological advancements and the military and commercial march of Western powers, particularly during the 19th century.
Both empires contended with political fragmentation, military challenges, and the failure to adapt to the changing world around them. The Ottomans also faced intervention by European powers and internal nationalistic movements that expedited the empire's disintegration. Eventually, the Ottomans could not withstand the tides of change that came with World War I, heralding the end of their empire with the abolition of the caliphate in 1924.