The other assumption Ted Neward said he was questioning these days (at least, the other one I want to comment on) is that strongly typed languages are likely to be more efficient, because they give the compiler or VM more information that can be used to optimize things.
That may well be true. But I think the gap between the two is surely narrowing, to the point where (combined with increases in hardware speed) it’s usually a non-issue.
Untyped languages can be really fast. Check out all the cool Smalltalk things in Alan Kay’s keynote at ETech. I’ve been trying to find the time to start serious work on an app I want to write. As part of trying to decide what language to write it in, I’ve written essentially the same program in ObC/Cocoa, Java, and RubyCocoa. The ObC version is fastest, but not by much, and the Java and RubyCocoa versions perform almost identically.
It’s also interesting to reflect that the technology in Hotspot that makes modern Java pretty fast originated in attempts to make Self run fast, and Self is as dynamically typed as a language can be.
The history of programming language optimization is mostly the same story repeating. Languages include features and constructs designed to help the runtime system be efficient. And then implementation technology advances, and those same things that once helped the compiler generate fast code are suddenly inhibiting that process. I wonder whether the same thing will happen with static typing?