Zinn's main purpose in writing is to liberate the discipline of history from stasis and a sense of detachment from impacting political, economic, and social change. Zinn believes that history can be an agent of change. Essentially, he sees it come down to a fairly simple reality. Either history will be appropriated, as he seeks to do, as an agent of change or it will become a tool of those who do not want this change to happen. Zinn sees history as becoming a tool of liberation for many or it will become another example of silencing voices.
In quoting Kissinger's idea that "history is the memory of states," Zinn wishes to recast this in making it a memory of the people. Zinn believes that this will yield a more democratic reality for there are more people who are silenced and oppressed than those who are not. In this, Zinn hopes to see the world become more fair and just. In short, Zinn believes that in the recasting of history with a slant towards impacting and creating social change, the promises and possibilities of what democracy can be are more closely realized.