The question is interesting, but I am not sure the author’s analysis is correct. For example, consider his interpretation of the OSI version of “free”:

Open-source software, per the OSI, is free, “free” as in “free beer” rather than necessarily as in “free speech,” which latter usage of “free” carries with it certain responsibilities.

But, the first portion of this is clearly incorrect, as the OSI requires free redistribution. That is, you can certainly charge for Open Source software if you like, but you can not require others to do so, demand a royalty for re-distribution or so on. You can charge for your portion of distribution all you like, as much as you like.

“Free” in the FLOSS realm has always been more focused on the “free speech” side, with the “free beer” side being more of a happy side effect. In fact, I would say that the OSI definition very specifically and necessarily requires the “free speech” aspect (and the attending responsibilities).

I don’t want to pick apart the gentleman’s analysis – because although I might not agree with it, I do think he raises an interesting question: What is the Opposite of Open Source?

Defining Open Source

In order to determine the opposite of something, it helps a bit to be able to define that something. It’s easy to say the opposite of tall is short, because you are only considering one aspect or dimension of the something. With Open Source, though there is more than one aspect.

Is something the opposite of Open Source if it only contradicts one aspect?

Consider if there were some Closed Source application that was identical to an existing Open Source application, the sole difference being the visibility of the source. While that is clearly not Open Source, I am not so sure it is the opposite of Open Source.

The visibility of source code is a necessary, but not sufficient, characteristic of Open Source. Without hashing over existing or proposing new definitions, perhaps we can agree that ensuring end-user freedom is another characteristic.

Indeed, some may propose that ensuring end-user freedom is necessary and sufficient, as any other characteristic can be determined against that standard.

So, similarly to how source code visibility alone is not Open Source, we need a special class of Closed Source software to really qualify as the opposite of Open Source. It must be some Closed Source software that actually takes away end-user freedom.

Is there is a class of such software?

I think if you consider such restrictive software in this light, it is easy to see why the FSF has the Defective by Design campaign to make users aware of the problem with what they call “Digital Restrictions Management” and “Treacherous Computing”.

Not only is (most) DRM software Closed Source; not only it is secretive in how it operates; but the whole reason it exists is to take away end-user freedom!

And that’s about as close to the opposite of Open Source as you can get.