Deepening and widening
These two terms describe what are arguably the two biggest schools of thought when it comes to the great debate over how the EU should develop. Supporters of deepening argue that the Union's member states should strive constantly to strengthen the links which bind them together. They argue that this approach is supported directly by the EU's founding Treaty of Rome, which stated that member states should work towards "ever closer union". Some proponents of widening argue that the Union should develop by including more member states, but the links between them should remain looser than those called for by the deepeners. But others argue that deepening and widening can occur simultaneously. The experience of the past two decades seems to have proved them right.