It seems to me that he is arguing that languages do not have a total ordering. As such, novices will argue that a language is strictly better than another, when a broader perspective will reveal that this is only true for some use cases.
The "no free lunch" theorem would indicate to me that there is no ultimate language, merely languages that are better for common (to you) use cases.
pg's argument reminds me of plato's dialogues where socrates confronts sophistry and searches for a universal truth. At first sight, it seems hard to make a primary ordering of programming languages, because they focus on different areas (ease of use, speed of development, performance etc) and ordering those disjunct areas against each other seems to be impossible. However, it is still possible for a programming language to focus and excel on all those areas at the same time. I am still hopeful of a language for the next 100 years; be it Arc or something else.
As a happy user of Ruby, Ruby excels in many of its promises. I wish Ruby-MRI focuses a bit on performance in coming versions. The ruby community needs this guy who developed the V8 javascript engine to do the same performance leap here too.(Maybe Rubinius or JRuby already do) That said, let us not forget that Twitter performance requirement is kind of extreme for most startups, and most JVM based languages and foremost Java lag in ease of use, speed of development etc to be a viable option for a startup. (I exclude here Clojure, Scala, JRuby etc). For most startups speed of development is what matters.
> At first sight, it seems hard to make a primary ordering of programming languages, because they focus on different areas (ease of use, speed of development, performance etc) and ordering those disjunct areas against each other seems to be impossible. However, it is still possible for a programming language to focus and excel on all those areas at the same time.
I disagree. There's more than ease of use, speed of development and performance to determine if a language is "better" suited to a problem than others. And they're all trade-offs to some point. So to excel at one means that you fall behind on others. Prolog is still used heavily in some areas since it's a natural fit to logic problems. It's just pure logic theory modeled in a programming language. It's a pityful language to solve most "real world" problems, but it excels at what it was made for. So is it "better" than ruby? I don't think so. Is it possible to write a language that models logic problems so nicely as Prolog and still keep the ease of use of ruby? I very much doubt that.
The "no free lunch" theorem would indicate to me that there is no ultimate language, merely languages that are better for common (to you) use cases.