An essay’s thesis statement is a statement that summarizes the argument you are trying to make. In your case, you want to compare the vision of the world suggested by the Preamble of the Constitution with the one presented in The Giver.
The preamble of the Constitution states that the Founding Fathers were trying to construct a “more perfect Union.” What exactly constitutes a perfect union? The world described in The Giver is one version of a perfect world, but would our ancestors agree? The “Declaration of Independence” states that our forefathers believed that “all men are created equal.” The does seem very close to the vision produced in Jonas’s society.
In order to compare the world the Founders envisioned with the one presented in The Giver in your thesis, you need to write a summary of what the founders of the country intended in these statements, and specifically by “a more perfect Union.” Here is an example.
The society presented in The Giver is more perfect than ours because everyone is treated equally and the safety of the people is their first priority.
The main point is to focus on what elements of Jonas’s society fulfill or exceed the vision presented by the Founding Fathers. For example, in Jonas’s society everyone is created equal—literally. People are actually created to be the same. They are all treated equally. They even look the same.
Almost every citizen in the community had dark eyes. His parents did, and Lily did, and so did all of his group members and friends. (Ch. 3)
Jonas’s community believes that peace can be promoted by keeping everyone the same, and ensuring that they act the same way through severe restrictions on behavior and conditioning to make sure everyone has almost no personality.
Perfect is sometimes not perfect, of course. The world created in the book could certainly be described as tyrannical. It is ironic that treating everyone the same makes everyone equally subjected.