  In this paper, one studies the famous well-known and challenging Tweety
Penguin Triangle Problem (TPTP or TP2) pointed out by Judea Pearl in one of his
books. We first present the solution of the TP2 based on the fallacious
Bayesian reasoning and prove that reasoning cannot be used to conclude on the
ability of the penguin-bird Tweety to fly or not to fly. Then we present in
details the counter-intuitive solution obtained from the Dempster-Shafer Theory
(DST). Finally, we show how the solution can be obtained with our new theory of
plausible and paradoxical reasoning (DSmT).
