Final answer:
Prince Shotoku centralized power by creating the Seventeen Article Constitution, which emphasized a unified state with a meritocratic civil service. He assimilated Confucian and Buddhist ideals, granting Tang-style honors and positions, and decreeing only direct royal descendants could rule, thus ensuring the centralization of power within his family.
Step-by-step explanation:
Prince Shotoku's Centralization of Power
Prince Shotoku attempted to keep power centralized within his family by implementing several strategic measures influenced by adjacent cultures and their political structures. The cornerstone of his centralization efforts was his establishment of the Seventeen Article Constitution in 604, which, influenced by Chinese Confucianism, laid out the vision for a unified state. This constitution promoted a meritocratic civil service and clarified the rights and obligations of both rulers and the ruled, in contrast to the decentralized clan-based power structure that existed at the time. Additionally, Prince Shotoku introduced Buddhism and Confucianism to delineate the Yamato line from all other clans, thus elevating the king's position.
Particularly noteworthy were his subsequent policies that rewarded supporters with Tang-style court ranks and positions within a Tang-style government structure. By granting these honors and official posts, he secured the allegiance of the aristocracy, who previously served as clan chiefs, thereby ensuring their acquiescence to centralized control. Furthermore, to cement the centralized power structure, only direct descendants of the royal family were decreed to hold the throne, securing the lineage of power within his own family.
An additional aspect of Shotoku's strategy to centralize power was his incorporation of Chinese culture and imperial statecraft into the Yamato rule. This adoption of external ideas not only strengthened his rule but also helped establish the king's godlike status, which was later transformed into the role of the emperor. The Kiyomihara Codes of 689 followed to structure society further, organizing monasteries, creating a judiciary, and managing the king's advisors and vassals.