In 1862, Abraham Lincoln asked, “If I should call a sheep’s tail a leg, how many legs would it have?” His wise answer: the sheep still has only four legs, “for my calling the tail a leg would not make it so.”

So yes, Europe can have an army. But calling a thing an army does not make it one.

An army must draw on a military culture. European cultures are profoundly unmilitary. The title of James Sheehan’s magisterial Where Have All the Soldiers Gone?: The Transformation of Modern Europe (2008) sums up how Europe has changed since 1945. Europe shows no sign of cultural militarization.

An army also needs money. European defense spending is low. Germany must be the core of any European army, and its defense spending is even lower. When the next recession hits, defense spending across Europe will fall again. Europe does not want to pay for an army.

An army must be sent by its national leaders to the battlefield. But Europe was split on the Balkans, Iraq, Libya, Georgia, and Ukraine. When Europe does take action, it is belated, limited, and usually divided. Europe has few core interests in common, so it will not be willing to send an army in common.

An army must be willing to fight. While a few national European armies are willing to fight, most are not. The restrictive rules of engagement that limited European forces in Afghanistan are notorious. European forces are largely limited to peacekeeping and patrolling. Europe does not want to fight.

And finally, if the army is to fight as an effective unit, it must actually think of itself as a unit. But the nations of Europe are very different places. There are no European political parties. Most sports leagues are national. The Champions’ League is not enough to make an Italian and a Pole want to kill and die for Europe. There are not enough Europeans who want kill and die for Europe to form an army.

The euro is not an economic currency. It was created for political reasons, and it remains political. As a result — witness Greece — it does not work. Similarly, a European army would not be created for military reasons. It would be created for a political reason: to pull defense away from the nations of Europe and to Brussels. If it is created, it will not work, because it will be a political army, not a real one.

In 1953, Winston Churchill derided the nascent European Defense Community as a “sludgy amalgam.” It never came into existence. Churchill was wise then, and his words are still wise today.

Europe can have an army in name if it chooses to create one. But it cannot have an army in reality because it has none of the necessities of an army. If Europe creates an army of illusion, it will be gambling its security in the belief that it needs a political army more than it needs a real one.

That would be a mistake. Mistakes of that kind are always found out. And they are always fatal.