Final answer:
Diocletian and Constantine undermined the stability of the Roman Empire through their respective actions. Diocletian's division of the empire into the tetrarchy created power struggles and Constantine's decision to move the capital weakened the western half of the empire.
Step-by-step explanation:
The emperors Diocletian and Constantine undermined the stability of the Roman Empire through their respective actions. Diocletian's division of the empire into the tetrarchy created a complex system of co-rulers that often led to power struggles and civil wars after his death. The constant changes in leadership weakened the empire's stability.
Constantine, on the other hand, moved the capital from Rome to Byzantium, which further shifted the balance of power towards the east. This shift contributed to the eventual decline of the western half of the empire, as attention and resources were focused on the eastern regions.