[true_religion]

> if your enemy thinks like you, talks like you, acts like you, shares your values and views the world the way you do, is he your enemy? Can he be your enemy? Why would he be your enemy?

Sure. Previous to the 20th century, most wars were fought over control over resources, land, and prestige.

[scottdw2]

In war, identity is a defined "negatively". That is, not by describing positive attributes to you, but by describing negative attributes to the enemy. "We are the opposite of x", hence we fight. If you neutralize the ability of the enemy to define you (because he is like you) he can't define himself, and so he cannot fight you. Thus, there is no enemy, and hence no war.

[true_religion]

I can accept that, but at the point you've already gone to war... it is pretty easy to point at any difference between you and the other country, and say that your way is better. (e.g. First World liberal democracy U.S.A looks down upon 1st world liberal democracy U.K. because U.K. has socialized healthcare thus clearly is insane).

[wozniacki]

  Sure. Previous to the 20th century, most wars were 
  fought  over control over resources, land, and 
  prestige.

Or over spurious differences like incompatible belief systems and divinities.

Spurious differences but holding a great deal of emotional charge.

edit: added quote.

[thaumasiotes]

From the 1974 The Four Musketeers:

    Porthos: I mean, what are we killing them for?
        Because they sing psalms in French, and we
        sing them in Latin?

    Aramis: Porthos, have you no education? What
        do you think religious wars are all about?

[aaronem]

"Previous to the 20th century?"

[ekianjo]

most of these were driven by governments and empires, not people. as an ndividual you have everything to lose to go to war.