1) Call into question 2) Challenge 3) Dispute 4) Question 5) To call in question 6) To contradict or controvert 7) To oppose 
to attack by argument; to oppose; to call in question
• (v. t.) To fight against; to attack; to be in conflict with; to oppose; to resist.
Op·pugn' transitive verb [ imperfect & past participle Oppugned ; p pr. & verbal noun Oppugning .] [ Old French oppugner , Latin oppugnare ; ob (see Ob- ) + pugnare to fight. See Impugn .] To...
oppugn 1. To question the validity or truthfulness of something. 2. To oppose, to contradict, or to call into question. 3. To assail by criticism, argument, or action.
call into question verb challenge the accuracy, probity, or propriety of; `We must question your judgment in this matter`