Intelligence comes from the Latin verb "intellegere", which means "to understand". By this rationale, intelligence (as understanding) is arguably different from being "smart" (able to adapt to one's environment), or being "clever" (able to creatively adapt).
At least two major "consensus" definitions of intelligence have been proposed. First, from Intelligence: Knowns and Unknowns, a report of a task force convened by the American Psychological Association in 1995:
Individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought. Although these individual differences can be substantial, they are never entirely consistent: a given person’s intellectual performance will vary on different occasions, in different domains, as judged by different criteria. Concepts of "intelligence" are attempts to clarify and organize this complex set of phenomena. Although considerable clarity has been achieved in some areas, no such conceptualization has yet answered all the important questions and none commands universal assent. Indeed, when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen somewhat different definitions.
A second definition of intelligence comes from "Mainstream Science on Intelligence", which was signed by 52 intelligence researchers in 1994:
A very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings—"catching on", "making sense" of things, or "figuring out" what to do.
Can we define intelligent behavior, give an analysis, norms, criteria? This is important if we want to get epistemology beyond the definition or conceptual analysis stage. Maybe epistemology – “The Theory of Knowledge”- is really, or should be regarded as a non- anthropomorphic theory of intelligent behavior, or more generally as theory of “intelligence” per se. But all these terms are prejudiced epistemologically , what do we do to get around this?
The Turing test is a test, an interactive communicative test.(It was for computers after all.) Can we not define intelligence without interactive communications? Can we have a purely observational test for intelligence, involving no interaction? Deciding on the basis of actions is hard. Suppose we have a really good robot that makes car parts and assembles cars, does this make it intelligent? Suppose it starts with raw materials, iron ore, silica, raw rubber and produces a Ferrari, does this make it smart or just well programmed and capable? Could it not pass all the Wikipedia tests above and still not be intelligent. It could be adaptive, it could learn, modify its behavior, even be said to grasp abstract ideas.. These are performance criteria which could in principle be met by machines not much more advanced than those that exist today .Didn’t Big Blue, the chess playing program grasp, in effect, the abstractions in chess?
A system can evidence something we might, primitively, want to call intelligence, via its external behavior ,i.e., behavior we can observe without reference to the internal states of the system. Why would we call this intelligent behavior?. Probably because we observe that it is reactive, the systems performance depends on the external situation. (We actually generally do this on inference maybe, if it acts like us its smart.) If we don’t know its reactive we have a problem. Imagine an mechanical arm coming through a wall making marks on paper, a simpler Turing test.. Whether or not we think it intelligent depends what we make of the marks on the paper whether we think they are wrote learning or creative, assuming we can make any sense out of them at all.. It is impossible to determine externally whether the system is intelligent or not unless it is reactive. And this reactivity must be information based.