Interests, Ideas or Both?

Goldstein and Keohane as well as Max Weber discuss the concept and argument of whether or not ideas or interests influence political decision making. While both conclude that both interests and ideas influence political outcomes, I wonder why this has become a debate at all? It seems to me that from every angle and article that this topic has been discussed, there is a general consensus that both are extremely important in International Relations.

When you think about the rivalry between interests and ideas, it almost seems absurd. Interests do not just spring up from anywhere. They begin with an idea about how things are or should be... Values determine interests and values are ultimately created by ideas- ideas of what is or is not important in the world...

I suppose I may be missing the whole point of this historical argument by saying that it is essentially futile, but so far I have only heard and read the beliefs that both interests and ideas are important in political decision making. So why is there a rivalry? There should simply be a different causal focus in creating theories and models instead.

I suppose this may be represented by a sort of constructivist view... I am not sure. There is more to be said on this possibly later on.

Side Note:

Here is a random interesting article I found on the effect of public opinion on political decisions.