Are There Absolutes?

How can we know anything?  I mean ANYTHING?

Frankly, it is often a good policy to doubt everything.  And the more information we get, the more we doubt.  Every time someone sends me information, I want to check it out on snopes.com.  But how do I know that snopes is accurate?  We've learned that the maps we learn geography on are inaccurate, that dictionaries are changable, that encyclopedias only give one point of view.  What our grade school teachers taught us is corrected in high school and that is corrected in college and in real life we learn the issues we spent so much time on in school are insignificant (think about the various things we learned about the Pilgrims and Thanksgiving).

How can we absolutely trust any piece of information, let alone answers to big questions?  Is anything we learn actually, permanently true?  Or is it only temporarily true until the next scientific study?  Is our most firm observations and truths that we base our lives on merely guesses?  Are they only cultural artifacts that will be replaced in the next generation?

Is there anything that we can rest on as solid evidence?  Descartes claimed that the only solid evidential proof we can have is "I think, therefore I am".  But even in that, aren't there assumptions in that statement about what "I" is?  Am "I" personal?  Perhaps "I" is not an "I", meaning an individual, but an entity, a machine, or a collective?

And what if we can know nothing in an absolute sense-- does this mean that we cannot make truth claims? Is every bit of truth only able to be proceeded with "I think" or "I believe"?