The word "intelligence" comes from Latin "intelligo" which means "I understand". So, the basic meaning of intelligence is the ability to understand, or to "get it", so to speak. Everyone has it, but not to the same degree (hence IQ). People who get it faster are considered more intelligent than others.

It may be interesting to analyze the word further. "Intelligo" is actually "inter-ligo", that is, "I tie between". That would indicate that intelligence is the ability of seeing relationships among things and ideas, the ability "to put it all together."

Garrison Keillor once said that intelligence is like 4-wheel drive. It only allows you get stuck in more remote places.

It's been said enough that the smarter you get, the harder it is to either find happiness, stay sane, or both. Sometimes you simply get tangled up in your thoughts by being even slightly intelligent because normal everyday functions suddenly become infused with potential meaning.

You question more, you become overwhelmed with the directions things can take, you try to follow chain reactions in the world and find that they don't really end, ever. Some people would say that insanity in light of intelligence is a blessing, a deliverance. For others, that's the end to avoid, to stay just above water. And for even others, ignorance is bliss.

If I am intelligent at all, old Garrison is onto something.

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

What is Intelligence?

Intelligence is the ability to think clearly, reason logically or analytically, obtain and process new knowledge, solve problems, understand complex concepts, and communicate knowledge to others. It is not fully known what causes variations in intelligence (at the lowest level) although very recent research has indicated that it is related to the neuron firing speed in the brain (which differs from person to person.) It is established in the scientific community that intelligence is caused both by genetic factors and environmental factors, with between 40% and 80% of all intelligence variation being dependent on genes. 1

Intelligence or cognitive processing ability is fixed by the age of six in almost every case (exceptions are extraordinarily rare.) It is well-known in psychology that to have any effect on the intelligence of a person intervention must occur very early in life. Unfortunately, despite this, little success has ever been achieved in permanently raising intelligence via such intervention. The greatest effects on intelligence have been observed in neo-natal and early childhood nutrition and medical care. Although some studies or programs have purported to achieve lasting effects, the science of these efforts has been questionable, or the results irreproducible.

The I.Q. Connection

Many think of intelligence when they hear the term I.Q.. This is both exactly correct and wildly inaccurate. I.Q., or "intelligence quotient" was originally defined as a person's mental age divided by their physical age. If a 10 year-old could perform the mental tasks of a 16 year-old, they had an I.Q. of 160. This number was determined by the intelligence tests of the day (the early 1920's) and was held to accurately represent intelligence itself. However, it is extremely important to note that I.Q. only means the score one can achieve on an I.Q. test. It can only measure actual intelligence if the test contains the correct style of questions and is administered properly. I.Q. is only a valid measure of intelligence if the test it comes from is also valid.

The belief in the ability of a test to measure general intelligence is based on the work of British psychologist Charles Spearman. In 1904 Spearman noticed that many tests of mental ability were all correlated with one another -- a person who did well on one test was likely to do well on all others also. 2 Spearman took his data and applied a statistical method called factor analysis. He concluded that all of the correlation could be accurately explained by one factor, which he called the general intelligence factor, or g.

The Great g  Debate

From Spearman's time until the late 1970's, debate has raged about what g  is, what it means, and whether it actually exists or if it is merely a statistical artifact. Though these arguments have been laid to rest in the professional psychometric community, they remain abroad in the popular consciousness. In this respect, the prevailing wisdom is far behind the state of scientific knowledge. This is primarily due to the efforts of a liberal establishment that dislikes the implications of a g  that exists and has real meaning.

The argument against g   is that it is simply a creation of statistics obtained by manipulating the factor analysis in a certain manner. For decades, psychometricians studied, searched, and analyzed the data with the hope of obtaining "multiple intelligence factors" that explained intelligence better than Spearman's g. The search, in short, was fruitless. No method of factor analysis can produce any group of variables that explain test correlations better than g. In short, g does exist and is here to stay. In his book The Mismeasure of Man, Stephen Jay Gould uses this argument as his means of rejecting the notion of g. It should be noted that this argument no longer has any scientific standing among professionals in the field, based on overwhelming evidence against it.

Effects of Intelligence

Intelligence has a large statistical impact on society and everyday life. Many societal phenomenons, including poverty, education, wage earnings, crime, and others, correlate strongly with intelligence -- more than any other factor. While these things are typically studied in terms of class background or educational level, it is clearly shown by studies that intelligence explains these social phenomena (in general) far better than any other factor. In fact, some previously obvious correlations disappear when intelligence is taken into account. A complete study of these effects is the goal of The Bell Curve, by Richard Herrnstein and Charles Murray. (Contrary to popular opinion, the book is not about race.) Due to the huge effects intelligence has on societal trends, the study of it is of major importance, and the ability to genuinely improve intelligence should be highly sought after by scientists and laypeople alike.


1. Richard Herrnstein, Charles Murray. The Bell Curve. New York City: Simon & Schuster, 1994.

2. "Intelligence." Microsoft Encarta Online. Microsoft Corp. Wed. Nov 12, 2002.

Other information from personal knowledge and consultation with teachers and professors in the field.

Intelligence means both the product and the process of systematically collecting, collating and analysing raw information so as to understand a situation.

The term is more commonly used in the context of protecting and supporting a country's national interests (military intelligence, which includes the 'big picture' strategic intelligence and 'battlefield' tactical intelligence). Law enforcement agencies apply criminal intelligence in fighting crime. Recently the term has also been applied to the activities businesses carry out in understanding and quantifying the markets they are targetting.

Information - which would come from many different sources - needs to be documented as it is received. Its authenticity, relevance and contemporaneousness is evaluated, usually by assessing the reliability of the source and/or how it contradicts or complements known facts. Different sources produce different types of intelligence:

  • HUMINT: Human Source Intelligence - gaining information from people, through bribery, blackmail, encouraging defections etc.
  • SIGINT: Signal Intelligence - evesdropping on electronic communications.
  • IMINT: Imagery Intelligence - using satellites, aircraft, pilotless drones and other assets to intensively view a geographical region. IMINT is used more frequently now thanks to technological innovations.
  • MASINT: Measurement and Signature Intelligence - analysing the use of radio-communication devices (such as signal strength, rather than what is being said)
  • OSINT: Open source Intelligence. Researching from what has already been published.

    In putting each piece of worthwhile intelligence together, an appreciation is formed. With a better understanding of the situation, an intelligence analyst might then seek additional information by redirecting intelligence assets to concentrate on certain targets or patterns. Simulataneously, in the real world circumstances change and the appreciation needs to be constantly updated. The whole cyclical process is known as the intelligence cycle, and can be broken down into stages:

  • Planning and Direction
  • Collection
  • Processing
  • Analysis
  • Dissemination

    Counter-Intelligence is the process of detecting and preventing a rival organisation from gaining sensitive information and intelligence about your own country.

  • Behaviour can be confused with intelligence, especially when people have preconceptions about what an intelligent person looks like and how they behave. This reinforces the "intelligent" person's belief that he is intelligent. A person's ability in one aspect of intelligence (e.g. memory, language, mathematics, or IQ score) can also be confused with his overall intelligence and ability to coordinate the different aspects of his intelligence to adapt to his environment (e.g. earn a living, build friendships, enjoy life and become a valuable member of the larger community). A person who is intelligent can lose his intelligence if he believes that everything he thinks about is "intelligent" and "correct", and fails to recognize otherwise. In this case, as a result of not discerning between what is intelligent and what is not, his intelligence can go astray, unchallenged and unnoticed, to the point that it is lost and what remains is arrogance.

    In*tel"li*gence (?), n. [F. intelligence, L. intelligentia, intellegentia. See Intelligent.]


    The act or state of knowing; the exercise of the understanding.


    The capacity to know or understand; readiness of comprehension; the intellect, as a gift or an endowment.

    And dimmed with darkness their intelligence. Spenser.


    Information communicated; news; notice; advice.

    Intelligence is given where you are hid. Shak.


    Acquaintance; intercourse; familiarity.


    He lived rather in a fair intelligence than any friendship with the favorites. Clarendon.


    Knowledge imparted or acquired, whether by study, research, or experience; general information.

    I write as he that none intelligence Of meters hath, n flowers of sentence. Court of Love.


    An intelligent being or spirit; -- generally applied to pure spirits; as, a created intelligence.


    The great Intelligences fair That range above our mortal state, In circle round the blessed gate, Received and gave him welcome there. Tennyson.

    Intelligence office, an office where information may be obtained, particularly respecting servants to be hired.

    Syn. -- Understanding; intellect; instruction; advice; notice; notification; news; information; report.


    © Webster 1913.

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