The philosophical challenge of the novel is that it concerns an American who has been raised entirely by American Indians, without either formal education or religion.

Italians are still absorbing that reality and sifting through the related challenges, both practical and philosophical.

These groups often featured poetic lyrics loaded with indirect double-meanings and deeply philosophical challenges to the status quo.

So the idea of taking an antidepressant poses a philosophical challenge for many depressed people.

"For what kind of outlaw was this who rode my philosophical challenges as skillfully as he did his steed?"

Their existence and nature present special philosophical challenges: How do mathematical objects differ from their concrete representation?

His contempt was not unmingled with pity, but he has posed a disturbing, stark philosophical challenge.

There are major philosophical, cultural and ethical challenges facing the world in respect of which Europe can, and should, be a major player.

The book documents his first moneyless year, including many of the practical and philosophical challenges he faced.

And if it's a philosophical challenge, then it's a profound one, demanding the high poetry of self-destruction.