If you have a weak argument that falls apart as soon as anyone expresses any skepticism, this is an example of when you have anuntenable argument.
- that cannot be held, defended, or maintained
- incapable of being tenanted or occupied
- Not capable of being maintained or defended: an untenable position.
- Not capable of being occupied or lived in: untenable quarters.
- Usage Problem Insupportable; intolerable.
- un·ten′a·bil′i·ty, un·ten′a·ble·ness
(comparative more untenable, superlative most untenable)
- Not able to be held, as of an opinion or position; unholdable, indefensible.
- The theory of cold fusion was untenable.
- Nouns often used with "controversial": argument, doctrine, theory, hypothesis, view, position, notion, etc..
un- +"Ž tenable