The issue of “defining intelligence” has unreasonably taken far more effort than it should. The most prominent authors on the topic, such as Arthur Jensen, have argued it is not definable. Charles Spearman, the discoverer of g, believed we should not use the word “intelligence” due to its complexity.
The argument that defining “intelligence” is complex presupposes a definition of intelligence already exists in the same way disagreeing with any particular definition of intelligence presupposes one to exist. To say it is a complex problem in linguistics, psychometrics, psychology, etc. means that certain aspects of what “intelligence” is are already known. From these, we can construct some sort of general definition, so as to have solved the issue immediately.
The previous statement has its caveats. Some choose to define intelligence as knowledge of a cultural norm while some others choose to define it as mental ability. These are clearly distinct views of what the word “intelligence” means. Only one of these can be correct, or neither can be correct. But, it should not be understood that because there are competing definitions of intelligence, that none exists.
“Intelligence” is just a word. It really doesn’t matter what definition we choose to give it. The word was invented, not found. Therefore, the definition is invented as well. Attempts to “find” the true definition of intelligence are flawed from the start. What we can understand is that different people choose to define it differently and from that, we should just clarify what we mean by “intelligence”.
For this example, there are two people: John and Sam. Let’s say John has just thought up the word “intelligence” and he decides he is going to define it as being “mental ability”. Sam wants a word to define “cultural knowledge”. There is no rational reason Sam should want the word “intelligence” to be a placeholder for his definition. Sam is completely able to invent his own word. Yet, this is what happens. Everyone is competing over this word “intelligence” as if it has any importance whatsoever. It’s just a word.
I choose to define “intelligence” as “mental ability, reasoning ability, ability to acquire knowledge and apply it, cognitive processing ability, and the general ability represented by g“. You may think it means “information acquired in schooling” and I don’t really care – as long as we aren’t competing over something as simple as a word. If you’re really fed up over a stupid word then just read whatever I write, but whenever I write the word “intelligence”, pretend you just read the words, “mental ability, reasoning ability, ability to acquire knowledge and apply it, cognitive processing ability, and the general ability represented by g“. You know what I mean and whenever you use the word “intelligence”, as long as you explain your definition, then I know what you mean.
So, that’s as simple as it can get. Stop fighting over a word as if you have the ability to “find” its definition.