...Ask those people if they advocate sawing off the arms of the children of suspected terrorists to get information.

If they don't, then their motives are just due to a black heart and they are not really interested in the information...

That "technique" is against the law (and treaties) and constitutes torture:

Title 18, Part I, Chapter 113C, Section 2340.

...(D) the threat that another person will imminently be subjected to death, severe physical pain or suffering, or the administration or application of mind-altering substances or other procedures calculated to disrupt profoundly the senses or personality...

And, the "technique" ends up in false confessions:

Torture "R" Us

A guy is in Manhattan in a hotel next to the World Trade Center on September 11, 2001. The hotel is evacuated and he's not able to take all of his belongings with him. Later he tries to claim his belongings from the hotel - a passport, a religious book, and other items. Somehow the FBI is apprised of the situation - the claim is made that a radio transceiver was found with those belongings. The FBI interviews the guy. The guy says "that's not my radio." The FBI continues, more or less saying, "'fess up, or we'll turn your family over to people who'll make their life miserable." He confesses, out of fear for his family, in a confused sort of way. Later, an airline pilot shows up to recover his belongings and tells the hotel, "Where's my radio?" There's no connection between the two individuals.

Oopsie.