I didn't know what a libertarian was when I started reporting, writes John Stossel. I was just another liberal. I knew the Republicans were icky, and Democrats were more like me—except they didn't care about debt. I had no idea there was an actual movement of thinking people who want to honor the principles of the Founders—liberty and limited government. It took me a long time to wake up. Old politicians—and old voters collecting Social Security—may never change their minds. But libertarianism is growing fast among young Americans.