How Fox News defies ratings gravity

Forget about political winds and social trends. The dominance of Fox News in the cable ratings race has lasted through wartime and peacetime, boom and recession, Republican and Democrat. It's not a product of circumstance -- it's a law of nature: irresistible, irreducible and seemingly immutable.

In the just-ended May ratings period, Fox once again manhandled the competition, posting big gains in both primetime and full-day while MSNBC stumbled and CNN plunged headlong. Fox's primetime audience in the demographic of adults 25-to-54 (the ratings group that ad buys are based on) was up 30 percent versus May 2008; MSNBC's was down 9 percent, while CNN, which seems increasingly out of step with the cable news audience, tumbled a vertiginous 37 percent.