no basis
- unfoundedWithout factual support
- groundlessLacking factual support
- baselessLacking factual support
- unsubstantiatedWithout supporting evidence
- unsupportedLacking backing or proof
flimsy · empty · hollow · fabricated · invented · thin air · speculation · hearsay · conjecture · wishful thinking · spurious · unwarranted · unjustified · made up · smoke and mirrors · unproven · false premise · shaky
evidential foundation
no basiswell-founded
Having sound basis
strong foundation · well-grounded · evidence-based · substantiated · supported
legitimacy of grounds
no basisgood reason
just cause · warranted · defensible · reasonable grounds · merited
foundation/grounding
no basissolid foundation
strong foundation · well-grounded · well-founded · grounded · rooted