Balance and centrism go hand and hand. One cannot have balance without a center of balance, and one cannot have a center without balancing opposites. Politically, the main balance needed is between liberty and equality. Economically, that means a balance between economic liberty and economic equality. And similarly for health, education, transportation, and so forth.
One who focuses on liberty emphasizes freedom of action over a wide range. A free society is one in which people, as individuals and as groups, are free to act. The state exists to protect society from its enemies, both foreign states and individuals (e.g., pirates), as well as domestic groups and individuals (e.g., criminals) who would take away society’s freedom.
Those who focus on liberty are concerned that without it there is tyranny, which leads to depression (inwardly), anger (outwardly), and oppression toward those lacking political power.
One who focuses on equality emphasizes similarity of condition over a wide range. An egalitarian society is one which which people, as individuals and as groups, are in a similar condition. The state exists to protect society from its enemies, both foreign states (e.g., imperialists) and individuals as well as domestic groups (e.g., bad corporations) and individuals who would take away social equality.
Those who focus on equality are concerned that without it there is disparity, which leads to envy (inwardly), resentment (outwardly), and oppression toward those lacking political power.
These opposites are both legitimate concerns that should be balanced. The result will be imperfect no doubt but should then progress toward greater balance. True progress is movement toward balance.