Compassion is a very untenable ground.
Even after the rise of Stalin, when it became untenable to practice one’s faith, his father had not abandoned his beliefs.
...my position in Cuba is untenable.
The present increase in haulage in Europe is untenable in the long term.
Another untenable argument is that not only should the external costs be charged on but the external benefits should be credited.
Anything else would be untenable.
At present the situation is untenable.
Continuing the notion that everyone is equally interested in everything is untenable and discredits the EU itself.
David Cameron's position on the Lisbon Treaty is quite untenable.
EU policy - championed by the Council and the Commission - is untenable, cynical and unacceptable to the Arab population.
(of theories etc) incapable of being defended or justified: unreasonable, indefensible