Perhaps the best definition of intelligence can be found at the webpage of Evangelos Katsioulis. Intelligence refers to the ability of the human brain to perform. Performance is defined as logical thinking, short term memory, analysis of complicated patterns, general knowledge, predictions of sequence patterns, mathematical reasoning and ability, verbal ability and so on and so forth. Contrary to popular belief, not all humans are created equal. Some humans are more able than others to undertake and complete certain tasks. Since we are no longer in a state of barbarism (with the exception of militaries) physical prowess is no longer the factor which determines a person's survival. It is rather the ability to think, perform and produce.
IQ of course does not reveal the whole truth and it does not predict success. It merely states whether the potential for success exists or does not exist. The rest is up to the idividual. There have been many geniuses throughout history that contributed nothing. There have also been numerous geniuses who not only made important contributions but changed our understanding of the world and redefined the boundaries of human ability. Such geniuses include Plato, Aristotle, Socrates, Mozart, DaVinci, Voltaire and Nietzsche .
There is a difference in IQ values depending on the scale that is used. For example an IQ value of 145 in the SD 15 scale (3 standard deviations above the mean) is equal to IQ 148 in the SD 16 scale and IQ 172 in the SD 24 scale (this is the Cattell scale or ratio IQ scale). Here is an approximate scale of IQ classification in the (SD 16, SD 15) scales.
IQ (SD 16, SD 15)
(143, 140) and over - Genius or near genius (this is somewhat overstated!)
(125,123 - 143,140) Very superior intelligence
(116,114 -125,123) Superior Intelligence
(108,107 - 116,114) Above Average Intelligence
(90,89 - 108,107) Average or normal intelligence
80 - 90 Dullness
70 - 80 Borderline Deficiency
Below 70 Definite feeble-mindedness.
For more information on IQ classification and rarity chart please go to members.shaw.ca/delajara/IQtable.html.
For a list of IQ tests go here.
Intelligence (IQ) is not a very well defined concept. It is a multi-dimensonal quantity that is very difficult to measure. Howard Gardner's theory of multiple intelligences is probably one of the best approaches to modeling intelligence. The IQ concept as it currently stands, is approximatly correct.