1) Intelligence is a term which is difficult to define.
It covers a range of abilities, from basic sentience
(essentially, consciousness) to having a great deal of wisdom.
Its common use as a synonym for 'smart' makes the task of definition slightly more difficult,
as we begin to define intelligence as a personal quality such as beauty, talent, or athleticism.
I believe the best way to define intelligence is to recognise it as a broad definition.
Intelligence,then, can be seen as intellectual ability, from so basic a level as consciousness
(merely being aware of one's existence)-
to great wisdom and mental ability.
Therefore, at the simplest level, intelligent beings should be able to do any of the following to
qualify as sentient, and therefore intelligent:
~be aware of their existence.
To more rigidly define intelligence, as under this definition it could be argued that any l
iving creature possesses intelligence-
Subjects with an intelligence higher than that of mere sentiencce, should also:
~be able to question.
~be able to interact with their surrounds.
~have the ability to make choices.
~be able to acquire and apply knowledge.
~have the capacity for reason and logical thought.
I have divided the criteria for intelligence into two levels, because intelligence is a relative term.
Most people would agree that Einstein is more intelligent than Britney Spears,
and that Britney Spears is at least slightly more intelligent than a jellyfish. (*)
And all three subjects are sentient.
Following on from this definition of intelligence,
To "think" is more than merely to be sentient- Descartes said " I think, therefore I am"-
the fact of thought was proof enough of his existence, but the reverse is not true- merely existing does not imply thought.
For example, a fish may be aware of its existence, but it is not necessarily thinking- think is a verb, implying action of some sort.
to think is to consciously make decisions, have ideas, construct mental imagery. Thought is independent of external environment and other beings.