I made it clear in our dialogue that I was stipulating a particular definition for intelligence:
SBENTHALL: Would you say that Google is a super-human intelligence?
ME: Well, yeah, so we have to be very careful about all the words that we are using of course. What I mean by intelligence is this notion of what sometimes is called optimization power, which is the ability to achieve one's goals in a wide range of environments and a wide range of constraints. And so for example, humans have a lot more optimization power than chimpanzees. That's why even though we are slower than many animals and not as strong as many animals, we have this thing called intelligence that allows us to commence farming and science and build cities and put footprints on the moon. And so it is humans that are steering the future of the globe and not chimpanzees or stronger things like blue whales. So that's kind of the intuitive notion. There are lots of technical papers that would be more precise.
So, I'm not going to argue about the definition of intelligence. Likewise, I won't argue about the definition of rationality. What I mean by rationality is the concept of rationality from economics and cognitive science, though if we want to get philosophical then it gets more complicated than simple Bayesianism. (Aside: Is the theory of "communicative rationality" specified well enough that we can measure degrees of it, as we can with Bayesian rationality?)
As for this general line of argument about organizations and intelligence explosion, I refer to the earlier Hanson-Yudkowsky debate, especially (as Emile noted) the UberTool discussion. A summary of the Hanson-Yudkowsky debate is here.
I also refer interested parties to the comments here by gwern and by anonymous1.
I've realized I didn't address your direct query:
(Aside: Is the theory of "communicative rationality" specified well enough that we can measure degrees of it, as we can with Bayesian rationality?)
Not yet. It's a qualitatively described theory. I think it's probably possible to render it into quantitative terms, but as far as I know it has not yet been done.
If I understand the Singularitarian argument espoused by many members of this community (eg. Muehlhauser and Salamon), it goes something like this:
I'm in danger of getting into politics. Since I understand that political arguments are not welcome here, I will refer to these potentially unfriendly human intelligences broadly as organizations.
Smart organizations
By "organization" I mean something commonplace, with a twist. It's commonplace because I'm talking about a bunch of people coordinated somehow. The twist is that I want to include the information technology infrastructure used by that bunch of people within the extension of "organization".
Do organizations have intelligence? I think so. Here's some of the reasons why:
I talked with Mr. Muehlhauser about this specifically. I gather that at least at the time he thought human organizations should not be counted as intelligences (or at least as intelligences with the potential to become superintelligences) because they are not as versatile as human beings.
...and then...
I think that Muehlhauser is slightly mistaken on a few subtle but important points. I'm going to assert my position on them without much argument because I think they are fairly sensible, but if any reader disagrees I will try to defend them in the comments.
Mean organizations
* My preferred standard of rationality is communicative rationality, a Habermasian ideal of a rationality aimed at consensus through principled communication. As a consequence, when I believe a position to be rational, I believe that it is possible and desirable to convince other rational agents of it.