Intelligence is not only the ability to reason; it is also the ability to find relevant material in memory and to deploy attention when needed.

Intelligence, then, is the ability to attain goals in the face of obstacles by means of decisions based on rational (truth-obeying) rules. The computer scientists Allen Newell and Herbert Simon fleshed this idea out further by noting that intelligence consists of specifying a goal, assessing the current situation to see how it differs from the goal, and applying a set of operations that reduce the difference. Perhaps reassuringly, by this definition human beings, not just aliens, are intelligent. We have desires, and we pursue them using beliefs, which, when all goes well, are at least approximately or probabilistically true.

Intelligence is quickness to apprehend as distinct from ability, which is capacity to act wisely on the thing apprehended.

“Intelligence” demands the most strict of definitions, since the word is easily and often abused. Intelligence rates the quality of Gaean man’s competence at altering environment to suit his convenience, or, more generally, the solution of problems. The corollaries to the idea are several. Among them: In the absence of problems, intelligence cannot be measured. A creature with a large, complicated brain is not necessarily intelligent. Raw abstract intelligence is a meaningless concept.

Knowing a great deal is not the same as being smart; intelligence is not information alone but also judgement, the manner in which information is co-ordinated and used. Still, the amount of information to which we have accessed is one index of our intelligence.

Intelligence is the ability to adapt to change

Intelligence is what you use when you don't know what to do.

Intelligence is the ability of a species to live in harmony with its environment.

Intelligence is not only the ability to reason; it is also the ability to find relevant material in memory and to deploy attention when needed. Memory function is an attribute of System 1. However, everyone has the option of slowing down to conduct an active search of memory for all possibly relevant facts — just as they could slow down to check the intuitive answer in the bat-and-ball problem. The extent of deliberate checking and search is a characteristic of System 2, which varies among individuals.

Intelligence is not merely the capacity which enables us to profit by experience; it is the function of personality which gives experience its past, present and future meaning. Habits belong to existence, intelligence to living. Life becomes a creative venture in proportion to the amount and quality of intelligence which accompanies conduct.

Intelligence is the capacity to perceive the essential, the what is; and to awaken this capacity, in oneself and in others, is education.

Knowing a great deal is not the same as being smart; intelligence is not information alone but also judgement, the manner in which information is coordinated and used.

Historically, people have been naive about what qualities, if mechanized, would undeniably constitute intelligence. Is intelligence an ability to integrate functions symbolically? If so, then AI already exists, since symbolic integration routines outdo the best people in most cases.
If intelligence involves learning, creativity, emotional responses, a sense of beauty, a sense of self, then there is a long road ahead, and it may be that these will only be realized when we have totally duplicated a living brain.

Intelligence isn't just about what you know. It is also the ability to avoid being your own bottleneck.

• If you lack the skills, be willing to look foolish while you learn them.
• If you lack the connections, be courageous enough to reach out and build them.
• If you feel uncertain, be bold enough to figure it out along the way.

Many people have the ability, but they talk themselves out of trying.