arguable
contentious
debatable
disputable
disputed
moot
polemic
polemical
argumental
argumentative
at issue
belligerent
cat-and-dog
cat-and-doggish
combative
confutable
conjectural
contestable
controvertible
deniable
dialectic
disputatious
doubtable
doubtful
dubious
dubitable
eristic
factious
iffy
ill-humored
in dispute
in doubt
in dubio
in question
litigious
logomachic
mistakable
open to doubt
open to question
pilpulistic
pro and con
problematic
provocative
quarrelsome
questionable
refutable
scrappy
speculative
suppositional
controversialist
controversiality
controversy
controvert
controverter
critical
educational
fascinate
influential
philosophical
political
relevant
risky
unpopular
Herschel
commercial
inertial
noncommercial
noncontroversial
uncontroversial