Reasoning

If you and someone else want the same thing, should it ever matter if the reasons why are the same?

As an example, let's say you and your partner are in a relationship and you both want to be exclusive, both sexually and romantically.  Should it matter whether the reasons why you both want the same thing match up, or does it only matter that you both want the same thing?

In an attempt to answer that question I have considered a number of view points and the one I have settled on is that the motivation is as important as the desire, but more importantly the intent is perhaps the most crucial point.

Desires are relatively simple they can be defined loosely as what we want.  Wanting the same thing is a good way to build cooperation but it is short lived and it is very weak in terms of forging bonds.  Motivations are as important as they give us an idea of how people react to events in their lives.  Our desires are after all just responses to circumstances.  The easiest example to give is the desire to be rich which is motivated by poverty - actual or perceived.

If you want to know how someone might act in the future the best place to start is their past.  In our relationship example you want to know why they want the same thing so you can get an idea of how that desire will evolve.  Intent is the most important aspect here, while desire serves to answer what we want, and motivation serves to answer why we want it, intent serves to answer what we will do when we get it.  A Past, Present, and Future scenario.

The underlying issue for me personally in all of this is whether or not what you both want can or will lead to conflict in the future.  Understanding what we want, why we want it, and what we intend to do with it can give us a clearer picture of whether or not conflict is likely to arise.  Take an extreme example of a weapon of mass destruction.  The atomic bomb for example.  During its development there were a number of competing projects by different nations all with the same goal, to engineer a working atomic bomb.  This is an example of a shared desire.  What we know from history is that although the desire was the same, the motivation and the intent were different.  I'll go no further on this as it will likely cause division.

In our relationship example you need to understand all three aspects and determine whether they might cause conflict.  If they are likely to do so, then you should discuss this before you get what you want, as having it before you discuss it will add unnecessary pressure and could lead to resentment.