Furthermore, different explanations need not be mutually exclusive although some are, of course.

Other explanations of urban employment change, therefore, need to be explored.

Although this might well be the case, other explanations need to be considered.

But in general, we feel that such explanations need not be particularly powerful.

"Maybe that's as simple as any explanation needs to be."

Since this second explanation needs several assumptions to all be true, it is probably the wrong answer.

"No explanation needed, but thank you just the same."

Now, as I said in one of the quotes that we were talking about, a psychological explanation does not need to rest on physiological causes.

However, it is evident that pressure groups are, in fact, often formed on a large scale and some explanation needs to be offered.

Now, other explanations need to be found for the imbalance, they said.