  The study of QCD with two light dynamical fermions is of fundamental
importance to understand the mechanism of color confinement. We present results
of a numerical investigation on the order of the chiral phase transition with
$N_f = 2$ by use of a novel strategy in finite size scaling analysis. We
compare the critical behaviour of the specific heat, of the chiral
susceptibility and of the equation of state with the possible critical
behaviours. A second order transition in the O(4) and O(2) universality classes
are excluded by our data and substantial evidence emerges for a first order
transition. Like in most of previous works we have used the standard staggered
action with $L_t = 4$: possible scaling violations and the need for further
studies are discussed.
