In his textbook Contemporary World History what does Duiker mean when he says that the trend toward globalization may be offset by a simultaneous...

What Duiker means when he says this is that the move
towards globalization may not be the only move going on in the world.  There may be a
move going in the opposite direction.  This is the move towards fragmentation.  Duiker
says that the move towards fragmentation might be stronger than the move towards
globalization.

The move towards globalization is
well-known.  Many scholars believe that this move will make the people of the world grow
more and more similar to one another.  There will, they say, come to be a relatively
global culture where things like ethnicity and nationality will not matter
much.

But others argue that there is a different movement
happening.  This is the kind of movement that (one can argue) we see towards isolation
and nationalism in the US today.  Today, we worry about globalization and the way that
it takes our jobs and sends them to China.  Or we worry about the way that it brings
illegal immigrants into our country.  In response, we "fragment" ourselves and start
thinking about the world in terms of "us" versus "them."  We start to trust the rest of
the world less because it seems threatening.

This is what
Duiker is saying, that this second movement may end up being stronger than the first
movement.