Gabriele,

At least in the software industry most (if I remember correctly, somewhere around 80%) of the open source contributes are made, as part of their job responsibility, by individuals working for software for software development firms.

Open does not seem to mean the same thing in both contexts you want to address. While Open Source etc. means a lot of people will have access, can contribute and so on, the Popper term is related to freedom and similar values of democracy. He focuses on enemies and I doubt that Open Source can have enemies.

There are in Popper´s context obvious enemies, regarding the time when he wrote that. It was short after the Third Reich, arguably the most vicious totalitarian form of government history has ever seen. It was followed by a similar system in more countries such as the Soviet Union and China.

Popper addresses other things too. Not being an expert here, I just want to point to the mindframe and the debates that took place in various countries of the west. Popper has been criticised of advocating Liberalism by e.g. Ralf Dahrendorf, who claimed that Popper neglected social values. Herbert Marcuse was another critic "Repressive Tolerance".

So this is part of Popper´s political philosophy.

Popper's concept of openness seems rather akin to Richard Stallman's concept of free software than to that of Bruce Perens' open source.  Some 15 years younger than the former, the latter is a less ideological, not so leftish version of it, meant to deploy just the commercial potential of Stallman's ideas, as displayed, for example, by commercial Linux distributions.  Hence, the choice of the term "open" must have been coincidental.

By holding that knowledge and information had better be freely copyable —which is physically possible since they have no mass— the free software movement challenges business models based on intellectual property.  Its apologists look swayed by counter-cultural movements of the 1960s, which were reacting to wars of the same kind of the one which inspired The Open Society and its Enemies.  In addition, both Popper and Stallman exhibit a remarkable attitude at conflating technical stuff with its social consequences.

https://www.gnu.org/philosophy/philosophy.html

Ted,

You should take a look at some of the work by Jaron Lanier. He is a computer-scientist, cognitive scientist, computer science philosopher, visual artist and classical music composer. He has written several books on the dangers of the modern internet age, including the danger of "wikis," which I imagine mirrors in many ways the open-source tradition that has evolved in your field. 

Somewhat ironically, here's one quote from "One Half a Manifesto"  from the wikipedia page on him where I think investigation could uncover some interesting relationships between transistor count, software design, and human ideology.: 

'While transistor count increases according to Moore's law, overall performance rises only very slowly. According to Lanier, this is because human productivity in developing software increases only slightly, and software becomes more bloated and remains as error-prone as it ever was. "Simply put, software just won't allow it. Code can't keep up with processing power now, and it never will."[16] At the end he warns that the biggest problem of any theory (esp. ideology) is not that it is false, "but when it claims to be the sole and utterly complete path to understanding life and reality." The impression of objective necessity paralyzes the ability of humans to walk out of or to fight the paradigm and causes the self-fulfilling destiny which spoils people.'

https://en.wikipedia.org/wiki/Jaron_Lanier#.22One-Half_of_a_Manifesto.22_.282000.29

Another relevant quote from wikipedia in which Lanier directly criticizes the "open source" movement as a form of "Digital Maoism":

You Are Not a Gadget (2010)

In his book You Are Not a Gadget (2010), Lanier criticizes what he perceives as the hive mind of Web 2.0 (wisdom of the crowd) and describes the open source and open content expropriation of intellectual production as a form of "Digital Maoism".[21] Lanier argues that Web 2.0 developments have retarded progress and innovation and glorified the collective at the expense of the individual. He criticizes Wikipedia and Linux as examples of this problem; Wikipedia for what he sees as: its "mob rule" by anonymous editors, the weakness of its non-scientific content, and its bullying of experts. Lanier also argues that there are limitations to certain aspects of the open source and content movement in that they lack the ability to create anything truly new and innovative. For example, Lanier argues that the open source movement didn't create the iPhone. In another example, Lanier claims that Web 2.0 makes search engines lazy, destroys the potential of innovative websites like Thinkquest, and hampers the communication of ideas like mathematics to a wider audience. Lanier further argues that the open source approach has destroyed opportunities for the middle class to finance content creation, and results in the concentration of wealth in a few individuals—"the lords of the clouds"—people who, more by virtue of luck rather than true innovation, manage to insert themselves as content concentrators at strategic times and locations in the cloud. In the book, Lanier criticizes the MIDI Standard for musical instrument commonality. His comments brought on rebukes from industry and artists knowledgeable of the standard and suggestions that Lanier published his comments merely as bait for debate.

https://en.wikipedia.org/wiki/Jaron_Lanier#You_Are_Not_a_Gadget_.282010.29

Here is his criticism of wikis: 

Wikipedia and the omniscience of collective wisdom

In his online essay "Digital Maoism: The Hazards of the New Online Collectivism", in Edge magazine in May 2006, Lanier criticized the sometimes-claimed omniscience of collective wisdom (including examples such as the Wikipedia article about himself, which he says recurrently exaggerates his film directing work), describing it as "digital Maoism".[18] He writes "If we start to believe that the Internet itself is an entity that has something to say, we're devaluing those people [creating the content] and making ourselves into idiots."[18]

His criticism aims at several targets which concern him and are at different levels of abstraction:

any attempt to create one final authoritative bottleneck which channels the knowledge onto society is wrong, regardless whether it is a Wikipedia or any algorithmically created system producing meta information,

sterile style of wiki writing is undesirable because:it removes the touch with the real author of original information, it filters the subtlety of his opinions, essential information (for example, the graphical context of original sources) is lost, it creates a false sense of authority behind the information,

collective authorship tends to produce or align to mainstream or organizational beliefs, he worries that collectively created works may be manipulated behind the scenes by anonymous groups of editors who bear no visible responsibility, and that this kind of activity might create future totalitarian systems as these are basically grounded on misbehaved collectives which oppress individuals.

This critique is further explored in an interview with him on Radio National's The Philosopher's Zone, where he is critical of the denatured effect which "removes the scent of people".[19]

In December 2006 Lanier followed up his critique of the collective wisdom with an article in Edge titled "Beware the Online Collective".[20] Lanier writes:

I wonder if some aspect of human nature evolved in the context of competing packs. We might be genetically wired to be vulnerable to the lure of the mob....What's to stop an online mass of anonymous but connected people from suddenly turning into a mean mob, just like masses of people have time and time again in the history of every human culture? It's amazing that details in the design of online software can bring out such varied potentials in human behavior. It's time to think about that power on a moral basis.

Lanier argues that the search for deeper information in any area sooner or later requires that you find information that has been produced by a single person, or a few devoted individuals: "You have to have a chance to sense personality in order for language to have its full meaning."[20] That is, he sees limitations in the utility of an encyclopedia produced by only partially interested third parties as a form of communication.

https://en.wikipedia.org/wiki/Jaron_Lanier#Wikipedia_and_the_omniscience_of_collective_wisdom

Hope this helps!

Thank you to everyone who has answered so far - if this site had a feature for commenting on individual answers I would do that (i have suggested this feature before).

I have come across an official history of the term open source at opensource.org, and am sharing it here. It's clear that both philosophical and political issues guided the selection of the term, making me even more intrigued about the complex history of terms like 'open' and 'free' in discourses on science and technology.

Coining “Open Source” (reproduced from opensource.org/history)

The “open source” label was created at a strategy session held on February 3rd, 1998 in Palo Alto, California, shortly after the announcement of the release of the Netscape source code. The strategy session grew from a realization that the attention around the Netscape announcement had created an opportunity to educate and advocate for the superiority of an open development process.

The conferees believed the pragmatic, business-case grounds that had motivated Netscape to release their code illustrated a valuable way to engage with potential software users and developers, and convince them to create and improve source code by participating in an engaged community. The conferees also believed that it would be useful to have a single label that identified this approach and distinguished it from the philosophically- and politically-focused label "free software." Brainstorming for this new label eventually converged on the term "open source", originally suggested by Christine Peterson.

Two of those present at the Palo Alto meeting (Eric Raymond and Michael Tiemann) would later serve as presidents of OSI, and other attendees (including Todd Anderson, Jon “maddog” Hall, Larry Augustin, and Sam Ockman) became key early supporters of the organization.

Adoption of the term was swift, with early support from figures in the community, like Linus Torvalds, and from an April 1998 Free Software Summit attended by many key individuals, including the founding figures of sendmail, Perl, Python, Apache, and representatives from the IETF and Internet Software Consortium.