"Small is beautiful" was a radical challenge to the 20th century's intoxication with what Schumacher described as "gigantism".

As theatrical works, both these shows are radical challenges to Broadway establishment thinking.

As some critics point out, West's novel was a radical challenge to modernist literature.

Another case he had taken on, an even more radical challenge to the system, was now headed to a foreordained defeat.

They continued work on The Revolution which included radical feminist challenges to traditional female roles.

But, in fact, the precautionary principle poses a radical challenge to business as usual in a modern, capitalist, technological civilization.

It's a radical challenge that many listeners have been eager to accept.

Is your aim to pose a radical challenge to the traditional understanding of painting and sculpture?

But few historians would describe his presidency as a radical challenge to the status quo.

That seems a radical challenge to our freedom, and it is.