The definition of intelligence is one of the aims of
artificial intelligence - how can you create an
artificial version of something if you don't even know what that something is?
There have been many different 'definitions' of intelligence. "Intelligence is the ability to reason" is an example. But this tends to just push back the problem a little. What is reasoning? How do you tell 'good' reasoning from 'bad' reasoning, and how do you compare two different methods and say which is more 'intelligent'?
"Intelligence is the ability to learn and adapt" is another one. But learn what? Adapt how? To what purpose? Learning is important to intelligence, yes. But this is still too vague right now.
"Intelligence is the ability to solve problems" is our third attempt. This is a little more definate: A problem solved in a few key steps is a more intelligent algorithm than one solved in many similar ones. But this is not free of flaws either. If you take a computer and program it to do quicksort, this is an extremely intelligent algorithm. (The technique is unknown even to a lot of people). However, the computer has not learned the technique - it is simply following the instructions. The intelligence here lies in the mind of the programmer.
So, "intelligence is the ability to learn, adapt and apply problem solving methods". A mouthful, but a more comprehensive definition. This is the difference between a computer and a six-year-old doing addition; the six-year-old must learn how to do what the computer does with its hard wired registers and ALU. Problem solving is still the key, but the intelligent entity must create its own algorithms, adapt them to the shifting state of the problem at hand (often using mixtures of two or more methods), and discover for itself the best way to do things.
Hmm... good, but we have so far concentrated only on the process of solving a problem when it has already been well defined. But an intelligent entity also needs to discover the details of the problems, before it can go about solving them.
Thus, intelligence needs to:
Sadly, the best definition of intelligence I can find is not
summed up as a catchy phrase that fits into a 5 second
sound byte. Nevertheless, that is my final answer for now. (The three points above may in fact be
summarizable by a more
concise definition, however I cannot recognise the pattern, myself...) 8^7