No, Giok, your first assertion cannot be right. The proposed changes to the Treaty of Lisbon and enhanced enforcement mechanisms were (at least were thought to be) stabilising and of assistance in defending against currency speculators. The UK refusing to join such a thing impaired the plan's prospects of success simply because it reduced solidarity.

Additionally, if a Tobin tax reduces trading volumes that too will reduce volatility, although I'm doubtful if it would do so by much.

The real enemies are "financial markets" and we do not help ourselves by treating them as our masters. What we need to do is to control them.