The history of free software and open source software has a few influential works that it would be good for everyone involved to read. You don't need to agree, and some of them may be a bit obsolete, but it's good to know them.
The GNU Manifesto by RMS is where the free software movement formally started from. There was free software before it, but it defined the concept in a way that had perhaps never been expressed before, and galvanised the movement.
The Debian Social Contract formalises, for one major Linux distribution, uses the principles of the above two to explicitly specify the ethical foundation on which the project is built, and the values it holds.
The Four freedoms of software, as defined by the FSF, underlies all answers to the question, "is this free software". The [Debian Free Software Guidelines] and the OSI Open Source Definition build and expand on that, to be more practical and detailed for answering questions in practice.
In the beginning was the command line, an essay by Neal Stephenson, explains why the command line is maybe not a bad idea, even today.
A Declaration of the Independence of Cyberspace, by John Perry Barlow, proposes the online world as worthy of being thought of as an independent entity. That vision didn't really pan out. Code v2 by Lawrence Lessig discusses the reasons why not, and suggests another vision for the future.