1.
the 21st century can't be reduced to a set of principles

Corollary 1: don't believe anyone who is trying to sell you something.

Corollary 2: no one predicted the rapid dominance of fax machines, PCs, xerox copiers, cable TV, and Snapple; in fact the leaders, deep thinkers, and visionaries of all those industries made foolish predictions about how those things would never amount to much. Don't be so stupid as to think you can predict the "killer apps" of the next century, or even the next decade or year.

2.
nonlinearity

According to folklore, Columbus discovered that the world isn't flat. In the whirrled neither is the printed page. The 21st century is a hypertext universe. It's postmodernism pushed to its fullest extreme.

3.
space means nothing -- time means everything

Distances between people are irrelevant because of advances in transportation and communications. And yet, there are still only 24 hours in a day, and now you don't have the luxury of waiting a week for that package to come in the mail before your boss wants you to write your report.

Corollary: Power in the 21st century will derive from the ability to organize your life amid the sea of information that will bombard us, or the ability to sell tools that give other people that ability.

4.
the media is the message

Corollary: The media is the medium for all social interactions.

5.
TANSTAAFL

There ain't no such thing as a free lunch. We're living in a candy-store world created by technology and mass-production; that imposes on us a responsibility not to be apathetic, and to think about something other than ourselves.

6.
image is everything

Music, TV, and fashion matter.

7.
the future is now

According to Francis Fukuyama (following Hegel), we're at the end of history. We're closer to the 21st century than we are to Ronald Reagan's presidency, and closer to Jean-Luc Picard than to Leonardo Da Vinci. Live in the now, man!

8.
opposites are true. now what?

One way of characterizing the history of philosophy is as breaking down a series of fundamental propositions, deconstructing at an ever-deeper level until we have nothing but Derrida's "freeplay of the signifier". (cf. Hegel's thesis/antithesis leading to synthesis) This is also true in many other fields; all normative statements can be undermined. For any characterization we make about the 21st, we can also make the opposite characterization. E.g.: technology will set us free/technology will enslave us; we are entering a new age of grassroots activism/we are entering a new age of profound apathy; the social order is falling apart/new social organizations are forming; "high culture" is valuable/"pop culture" is profound; Neil Diamond is offal/Neil Diamond is a songwriting genius; the profit motive corrupts/buy our book. Just going around and pointing out contradictions, or seeking to prove that the bases for deeply-held beliefs can be undermined, gets us nowhere. We have to decide how to live our lives even though, as Nietzche says, God is dead (and, I add, so is Kurt Cobain).

9.
we need pop philosophy

We have pop music and pop psychology; why not pop philosophy? Bring philosophy out of the ivory tower and use it to make sense of a confused world. Marxism is dead, but Marx's thesis on Feuerbach lives -- "philsophers have interpreted the world. Now the task is to change it."

10.
the rules have changed, but it's still the same game

Underneath it all, we all want the same thing people have always wanted: to find happiness and meaning in life. Don't be afraid to do what makes you truly happy (but learn to distinguish happiness from momentary pleasure, which has value but of a different sort), never stop yourself from expressing what you believe in (but always question your beliefs), and always take action when deep down you know something is right (but always be mindful of the tragedy of the commons).