Internal Instability in the Roman Empire

Question 1

military problems

Answer 1

while the enemies had learned a lot from the Romans, their own military prowess had suffered a decline. the pay for the soldiers was most likely insufficiently raised after AD 83. the men who enlisted for citizenship had probably decreased quite a lot by this time. many notables who were enlisted lacked the military experience to be successful and useful in an army.
army units in certain areas had developed strong regional ties and interests.

Question 2

structural defects

Answer 2

taxation system was too simple and rigid to be effective and useful. no extra sources of income were present.
all over the empire, there were indefensible unfortified cities. trade was too dependent on the safe and peaceful transpirational conditions and there were not many reserves.
the state was also responsible for supporting the increasing numbers of poor seasonal labourers
and the poor lower classes had increased in numbers too.
wealth became increasingly disproportionately distributed.