I’ve been musing a bit over the articles I blogged on yesterday, and their call for greater theory development. My first reaction is to agree: we need a stronger theoretical foundation to the field of distance learning.
However, I’m also reminded of the proliferation of theories in the broader field of instructional design. Some would argue (like Merrill), that they are all based on the same foundational principles, which he terms “first principles.” If so, why the need for more and more variations of the same theme? If they are fundamentally different, how do we determine the direction of the field?
Perhaps distance learning hasn’t yet had it’s own proliferation of theories. But as we call for more theoretical research, I’m interested to see whether the work will support a few key “first principles,” or whether a smorgasbord (cacophony?) of ideas will result.
Lisa R. Halverson 
in Instructional Technology we have the added dimension of trying to parse out what an instructional theory is versus a learning theory – the differences between scientific development and technological development.
The question you raise is a good one. The way that I look at it is that we need to have some theories that allow us to apply and test principles.
I would consider Dave Merrill’s first principles an instructional theory.