equivocal
head-to-head
indeterminate
neck and neck
nip and tuck
nisi
absonant
contradictory
contrary to reason
fallacious
faulty
feeble
flawed
flimsy
groundless
illogical
inauthentic
incongruous
inconsequent
inconsequential
inconsistent
indecisive
indefinite
insubstantial
invalid
irrational
loose
nonscientific
not following
not proved
open
paralogical
poor
reasonless
self-annulling
self-contradictory
self-refuting
senseless
unascertained
unattested
unauthentic
unauthenticated
uncertain
uncertified
unconfirmed
unconnected
uncorroborated
undemonstrated
undetermined
unestablished
unfinished
unfixed
unfounded
unphilosophical
disappoint
fragmentary
fruitless
impractical
imprecise
inaccurate
ineffective
mislead
one-sided
pointless
unacceptable
unclear
uninformative
unproductive
unsatisfactory
wordy
abusive
allusive
collusive
conclusive
conducive
elusive
exclusive
illusive
inclusive
intrusive
nonexclusive
obtrusive
reclusive
unobtrusive