Which phrase encapsulates the idea of self-government in the Constitution?

The phrase "We the people..." encapsulates the idea of self-government in the Constitution because it emphasizes the foundational principle that the authority of the government is derived from the consent of the governed. This opening line of the Preamble to the U.S. Constitution signifies that the government is established to serve the interests and will of the people, not the other way around. It reflects the democratic philosophy that the citizens hold the ultimate power and responsibility in determining how they are governed.

This concept is central to self-government, as it acknowledges the role of individuals in shaping their governance and participating actively in the political process. The phrase embodies the collective will and unity of the populace, highlighting that the government is accountable to the people and must operate on their behalf. Thus, "We the people..." perfectly captures the essence of self-government as envisioned by the framers of the Constitution.