Deceptive argument

See: Fallacy.
Somewhat synonymous with specious argument (an argument that appears good at first view but is really fallacious).
Dependence on obscurantism
Deceptive language
Doublespeak
Obscurantist diplomatic language
See: Obscurantism. " The obscurity of diplomatic language 
corresponds neither to enhanced richness nor enhanced precision, but is 
the attempt to reconcile divergent and sometimes contradictory views by 
reaching an agreement which may be superficial and purely verbal."