Autocratic Rule and Lack of Accountability: Many emperors in the late period became increasingly authoritarian, concentrating power and disregarding the voices and concerns of the Senate, the traditional lawmaking body. This led to a lack of checks and balances and limited the participation of qualified individuals in decision-making, affecting the quality of governance.
Military Overemphasis and Internal Disputes: The constant state of military engagement, both external and internal, drained the empire's resources and manpower. Several emperors ascended to power through military coups, weakening the stability and cohesion of the empire. The Praetorian Guard, originally an elite imperial bodyguard, became involved in political power struggles, manipulating successions and assassinating emperors.
Taxation and Economic Issues: As military expenses increased, emperors resorted to heavy taxation, adding burden to the already struggling population. Economic disparities widened, leading to a decline in trade, commerce, and agricultural productivity. This contributed to social unrest and the depletion of the middle class, which had traditionally played a vital role in supporting the economy and maintaining social order.
Corruption and Administrative Incompetence: With autocracy and power concentrated, corruption became rampant in imperial administration. Officials often acted with impunity, leading to bribery, embezzlement, and abuse of power. This eroded trust in governmental institutions and led to inefficiency, hindering the empire's ability to effectively manage its provinces and resources.
Decline in Cultural and Intellectual Life: As military matters and political disputes consumed more attention and resources, cultural and intellectual pursuits suffered. Literature, philosophy, and the arts experienced a decline compared to earlier periods of Roman history. This weakening of cultural and intellectual vigor reduced the empire's long-term resilience and adaptability.
While the emperors played significant roles in the decline, the societal and structural issues within the Roman Empire were also major contributing factors. The emperors were at times symptoms and products of these challenges, struggling to maintain control and stability amidst external threats and internal divisions.