My first disagreement is that there have been too many cases where the world was suppose to come to an end and it didn't. Take Y2K for example, which was suppose to be a major catastrophic event. Instead it turned out to be nothing more than overactive imaginations at play. Everyone would love to know when the world is going to end, but that is just one thing that stretches beyond our grasp of knowledge. If an asteroid were headed toward earth and we had a countdown of so many weeks or days until the earth is destroyed, that would be understandable because there would be physical evidence to back this statement up. With the Mayans, however, it just seems like a guess made hundreds of years in advance with no evidence to prove the calendar true.
Secondly, if the Mayans truly could predict the future then why couldn't they predict their own annihilation? They foretold everything from eclipses to the Spanish arrival to doomsday, but they couldn't presage when they would get extinguished from this earth many, many years before the end of their calendar. That seems a little strange and ironic to me. So I choose not to listen to some extinct race that says when the world ends but was ignorant to their own fate.
Finally, seeing as the Mayans did get destroyed, who is to say that they even finished the calendar? Not one person will ever know if the Mayan race intended to continue writing the calendar long into the future beyond 2012 or if they purposely stopped on that specific date. Time can only tell, and I guess we will just have to wait until December 21, 2012 to truly know the answer. As for me it will just be another day of my life that, I believe, will continue long into the future.