I consider inheritance and polymorphism (and message-passing) to be
flipsides of one coin myself. Abstraction is what can be especially well
achieved by polymotphism and encapsulation.

But I still consider the presence of encapsulation, alone, to be merely
"object-based". Would you call a C project with separate modules, and
well-defined module boundaries and interfaces, to be "object-oriented"?
Most wouldn't call that "object-anything" although it has encapsulation. :)

Object oriented ultimately means that your most interesting things,
aside from atomic primitive values, tend to be objects, and that their
types are effectively ADTs rather than concrete. Encapsulation lets you
change the implementation in the next version without breaking the
client code. Encapsulation with polymorphism lets you change the
implementation at runtime or use different ones in different places
simultaneously. Now THAT's power. :)

(Object-based code in C is quite easy. Just declare a typedef void *foo
and a bunch of functions that accept a foo as their first parameter,
plus at least one factory function that returns a foo, in the header. In
the source code of the module, these methods make and return, or use, a
struct of some kind internally, casting the pointer. Iterators return a
node pointer as a void * and have a foo next(foo) function to advance
the pointer. Wrap the void * in a struct foo, actually, and the compiler
will complain if foo is used in place of bar, getting you back
typesafety after a fashion. If you want to allocate foos on the stack,
of course, the module has to expose a struct definition so client code
can take its size. Or it can have a different, kludgy factory function
pair: one returns the size of a foo without exposing implementation
details and the other accepts a char array and returns a foo using the
same memory -- client code stack allocates an appropriate-sized
structure using the first function to decide size, casts to char *, and
passes to the second function. Of course, this is all really ugly and
probably bug-prone anyway, so you should just use C++ or Java!)

[sNip]

    Heheh, that wording reminds me of Steve Ballmer not counting the fifth  
word "yeah" in a video where he said "I have four words for this company  
... I, love, this, company yeah!!!"

        http://video.google.com/videoplay?docid=-3446931931514285011&q=%22lumber%20cartel%22

    If the Java gods get angry, I'd be worried that objects might come  
crashing down to earth!