"All well stated Professor, but your initial instincts are also correct."

Said William, in the comments to my post about closing the White House to tourists.

My response: "Yes, but sometimes it happens that you decide to do something for the wrong reason and it happens to be a good decision for other reasons."

Can you think of some good examples?

I was going to say that my observation is related to but different from the idea of unintended consequences. But it seems to be the first of the 3 types of unintended consequences:

A positive, unexpected benefit (usually referred to as luck, serendipity or a windfall).

A negative, unexpected detriment occurring in addition to the desired effect of the policy (e.g., while irrigation schemes provide people with water for agriculture, they can increase waterborne diseases that have devastating health effects, such as schistosomiasis).

A perverse effect contrary to what was originally intended (when an intended solution makes a problem worse)