What does 'social leg' mean? Does that mean all of Europe must have same tax, employment, social laws? Why do you need to do this? Why can't you let each country have the work ethics and social protection they want? A consensus will never be achieved on these issues anyway. 'La fin désastreuse a répondu aux moyens indignes' Germain Tillion
One other way of asking this question would be to turn it around and say "if a consensus on so many very important things can never be achieved, why bother with this fiction, which Europe would therefore prove to be, in the first place?"
And if we can't be bothered with this fiction, I want my monetary and fiscal policy back, too. Fai de bèn a Bertrand, te lou rendra en cagant