Ninja'd, I was going to say it depends on the fiction you refer to.
Jep. Also, within a fictional system there are often differences between different kinds of dragons.
Similar to "dogs" not just being dogs but having different qualitities depending on race,
you will find animal like "lesser" dragons that may just spew a bit of fire
and stone-old "greater" dragons with an IQ of 220, a spell-repertoire well exceding Gandalfs
and the experience of many generations.
In Elements, I would consider the Bone-dragon to just be a mindless necroed golem, the
Ruby-dragon to be a savage beast and the Emerald dragon to be an extension to the
noble and sentient/sapient beastiarium of the woods.
The light- and phase-dragon have outerwordly qualitities so things such as "recognizing oneself"
or "logic" are either a mere joke for them or simply incomprehendable for they are not part of
the way their world works.
And so on ...