A concept is a complex association in the memory of sensory images, perceived relationships and abstracted formal constructs. The network of associations of a concept is usually activated in the awareness by the stimulus of one of the elements of that network...be it a word, image, or recollected experience. A concept is a psychic fabrication induced from experience. It is a conscious awareness of perceived or imagined form or relationships. Concepts are the sub-structures of the further complexifications of reality models. A concept is an entity but not a physical object. It does not exist in space or time independently of minds. A concept will never be any sort of irreducible quantum of thought which is somehow an objective logical element common to different minds. It may be useful to suppose there are elementary sensory quanta which simulate a concept and perhaps participate in its network of associations, but such attempts are likely to be further exercises in philosophical wrestling with faeries.

The concept of a frog is not to be identified naively with some sort of visual image, however much that is what is recovered from the memory first, after the focal stimulus of the word frog. Frogness will be a concept of variable complexity depending upon the experience and interest of the possessor. It is unlikely that any two individuals will have identical frogness concepts yet as long as there are adequate similarities between the two, communication about frogs can proceed. Infants would have, at most, a concept constructed of simple forms of size, shape, colour, sound and possible aquatic behaviour. A research scientist specializing in frog anatomy and behaviour would have an intricate web of associations of structure, biochemistry and ecology and be able to discriminate between Litoria aurea and many other species. Yet the two can quite successfully talk to one another about frogs. Even the supposed objectivity of mathematical concepts is illusory. No two individuals will ever have the same input of experiences which contribute to their concept of twoness yet they will manage to communicate in most circumstances perfectly adequately.

Even such seemingly objective concepts such as those of points and lines are not in fact universally elemental. The concept of a line which in one geometry supposes that parallel lines never meet is not the same concept in another geometry where this restriction is not enforced. The philosophical alchemists who attempt to purify concepts down to elemental quanta and thereby embark upon logically rebuilding the entire edifice of human knowledge simply indulge in a preposterous futility.

Most concepts are acquired, without there being a requirement to make statements about them, to become elements in the existential reality-model of the individual or of a group of individuals. It is a network of these conceptual constructs which is often what is called knowledge.

It is quite normal for humans to be biased thru circumstances of nurture with breath-takingly ludicrous concepts within the framework of a virtual non-reality system. These same concepts are sustained by a culture which ensures that any investigation into the reality of the framework is appropriately neutralized by whatever methods are available, comfortable and expedient. Religious and political concepts of superiority or revenge or nationalism or rapacity for resources, sustain the endless unresolvable histories of human conflict. The concept of life after death could scarcely be more monumentally oxymoronic yet countless millions of human individuals have incorporated it into the decisions of their everyday living. As well as all this of course, since the concept of a concept is about as much of a bootstrap airhoist of philosophical self-sustainability as is existentially possible, the basis for numerous impenetrable academic theses has been generously provided for.