In a popular sense, an idea arises in a reflex, spontaneous manner, even without thinking or serious reflection, for example, when we talk about the idea of a person or a place.
Plato was one of the earliest philosophers to provide a detailed discussion of ideas. He considered the concept of idea in the realm of metaphysics and its implications for epistemology. He asserted that there is realm of Forms or Ideas, which exist independently of anyone who may have thought of these ideas. Material things are then imperfect and transient reflections or instantiations of the perfect and unchanging ideas. From this it follows that these Ideas are the principal reality (see also idealism). In contrast to the individual objects of sense experience, which undergo constant change and flux, Plato held that ideas are perfect, eternal, and immutable. Consequently, Plato considered that knowledge of material things is not really knowledge; real knowledge can only be had of unchanging ideas.
Descartes often wrote of the meaning of idea as an image or representation, often but not necessarily "in the mind", which was well known in the vernacular. In spite of the fact that Descartes is usually credited with the invention of the non-Platonic use of the term, we find him at first following this vernacular use.b In his Meditations on First Philosophy he says, "Some of my thoughts are like images of things, and it is to these alone that the name 'idea' properly belongs." He sometimes maintained that ideas were innate and uses of the term idea diverge from the original primary scholastic use. He provides multiple non-equivalent definitions of the term, uses it to refer to as many as six distinct kinds of entities, and divides ideas inconsistently into various genetic categories. For him knowledge took the form of ideas and philosophical investigation is the deep consideration of these ideas. Many times however his thoughts of knowledge and ideas were like those of Plotinus and Neoplatonism. In Neoplatonism the Intelligence (Nous) is the true first principle -- the determinate, referential 'foundation' (arkhe) -- of all existents; for it is not a self-sufficient entity like the One, but rather possesses the ability or capacity to contemplate both the One, as its prior, as well as its own thoughts, which Plotinus identifies with the Platonic Ideas or Forms (eide) A non-philosophical definition of Nous is good sense (a.k.a. "common sense"). Descartes is quoted as saying, "Of all things, good sense is the most fairly distributed: everyone thinks he is so well supplied with it that even those who are the hardest to satisfy in every other respect never desire more of it than they already have."
It should be observed that an idea, in the narrower and generally accepted sense of a mental reproduction, is frequently composite. That is, as in the example given above of the idea of chair, a great many objects, differing materially in detail, all call a single idea. When a man, for example, has obtained an idea of chairs in general by comparison with which he can say "This is a chair, that is a stool", he has what is known as an "abstract idea" distinct from the reproduction in his mind of any particular chair (see abstraction). Furthermore a complex idea may not have any corresponding physical object, though its particular constituent elements may severally be the reproductions of actual perceptions. Thus the idea of a centaur is a complex mental picture composed of the ideas of man and horse, that of a mermaid of a woman and a fish. htpp://wedofree.com
In mid-20th century, social scientists began to study how and why ideas spread from one person or culture to another. Everett Rogers pioneered diffusion of innovations studies, using research to prove factors in adoption and profiles of adopters of ideas. In 1976, Richard Dawkins suggested applying biological evolutionary theories to spread of ideas. He coined the term 'meme' to describe an abstract unit of selection, equivalent to the gene in evolutionary biology.
In the objective worth of our ideas there remains the problem of the validity. As all cognition is by ideas, it is obvious that the question of the validity of our ideas in this broad sense is that of the truth of our knowledge as a whole. Otherwise to dispute this is to take up the position of scepticism. This has often been pointed out as a means intellectual suicide. Any chain of reasoning (common sense) by which it is attempted to demonstrate the falsity of our ideas has to employ the very concept of ideas itself. Then insofar as it demands assent to the conclusion, it implies belief in the validity of all the ideas employed in the premises of the argument.
To assent the fundamental mathematical and logical axioms, including that of the principle of contradiction, implies admission of the truth of the ideas expressed in these principles. With respect to the objective worth of ideas, as involved in perception generally, the question raised is that of the existence of an independent material world comprising other human beings. The idealism of David Hume and John Stuart Mill would lead logically to solipsism (the denial of any others besides ourselves). The main foundation of all idealism and scepticism is the assumption (explicit or implicit), that the mind can never know what is outside of itself. This is to say that an idea as a cognition can never go outside of itself. This can be further expressed as we can never reach to and mentally apprehend anything outside of anything of what is actually a present state of our own consciousness.
What is possible for a human mind to apprehend cannot be laid down beforehand. It must be ascertained by careful observations and by study of the process of cognition. This postulates that the mind cannot apprehend or cognize any reality existing outside of itself and is not only a self-evident proposition, it is directly contrary to what such observation and the testimony of mankind affirms to be our actual intellectual experience.
John Stuart Mill and most extreme idealists have to admit the validity of memory and expectation. This is to say that in every act of memory or expectation which refers to any experience outside the present instant, our cognition is transcending the present modifications of the mind and judging about reality beyond and distinct from the present states of consciousness. Considering the question as specially concerned with universal concepts, only the theory of moderate realism adopted by Aristotle and Saint Thomas can claim to guarantee objective value to our ideas. According to the nominalist and conceptualist theories there is no true correlate in rerum naturâ corresponding to the universal term.
Mathematics, astronomy, physics, chemistry, and the rest claim that their universal propositions are true and deal with realities. It is involved in the very notion of science that the physical laws formulated by the mind do mirror the working of agents in the external universe. The general terms of these sciences and the ideas which they signify have objective correlatives in the common natures and essences of the objects with which these sciences deal. Otherwise these general statements are unreal and each science is nothing more than a consistently arranged system of barren propositions deduced from empty arbitrary definitions. These postulates then have no more genuine objective value than any other coherently devised scheme of artificial symbols standing for imaginary beings. However the fruitfulness of science and the constant verifications of its predictions are incompatible with such a hypothesis.
"It has been pretended by some, (and in England especially,) that inventors have a natural and exclusive right to their inventions, and not merely for their own lives, but inheritable to their heirs. But while it is a moot question whether the origin of any kind of property is derived from nature at all, it would be singular to admit a natural and even an hereditary right to inventors. It is agreed by those who have seriously considered the subject, that no individual has, of natural right, a separate property in an acre of land, for instance.
By an universal law, indeed, whatever, whether fixed or movable, belongs to all men equally and in common, is the property for the moment of him who occupies it, but when he relinquishes the occupation, the property goes with it. Stable ownership is the gift of social law, and is given late in the progress of society. It would be curious then, if an idea, the fugitive fermentation of an individual brain, could, of natural right, be claimed in exclusive and stable property.
If nature has made any one thing less susceptible than all others of exclusive property, it is the action of the thinking power called an idea, which an individual may exclusively possess as long as he keeps it to himself; but the moment it is divulged, it forces itself into the possession of every one, and the receiver cannot dispossess himself of it. Its peculiar character, too, is that no one possesses the less, because every other possesses the whole of it. He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me.
That ideas should freely spread from one to another over the globe, for the moral and mutual instruction of man, and improvement of his condition, seems to have been peculiarly and benevolently designed by nature, when she made them, like fire, expansible over all space, without lessening their density in any point, and like the air in which we breathe, move, and have our physical being, incapable of confinement or exclusive appropriation. Inventions then cannot, in nature, be a subject of property.
Society may give an exclusive right to the profits arising from them, as an encouragement to men to pursue ideas which may produce utility, but this may or may not be done, according to the will and convenience of the society, without claim or complaint from anybody. Accordingly, it is a fact, as far as I am informed, that England was, until we copied her, the only country on earth which ever, by a general law, gave a legal right to the exclusive use of an idea. In some other countries it is sometimes done, in a great case, and by a special and personal act, but, generally speaking, other nations have thought that these monopolies produce more embarrassment than advantage to society; and it may be observed that the nations which refuse monopolies of invention, are as fruitful as England in new and useful devices."
To protect the cause of invention and innovation, the legal constructions of Copyrights and Patents was established. Patent law regulates various aspects related to the functional manifestation of inventions based on new ideas or an incremental improvements to existing ones. Thus, patents have a direct relationship to ideas.
In some cases, authors can be granted limited legal monopolies on the manner in which certain works are expressed. This is known colloquially as copyright, although the term intellectual property is used mistakenly in place of copyright. Copyright law regulating the aforementioned monopolies generally does not cover the actual ideas. The law does not bestow the legal status of property upon ideas per se. Instead, laws purport to regulate events related to the usage, copying, production, sale and other forms of exploitation of the fundamental expression of a work, that may or may not carry ideas. Copyright law is fundamentally different to patent law in this respect: patents do grant monopolies on ideas (more on this below).
A copyright is meant to regulate some aspects of the usage of expressions of a work, not an idea. Thus, copyrights have a negative relationship to ideas.
Work means a tangible medium of expression. It may be an original or derivative work of art, be it literary, dramatic, musical recitation, artistic, related to sound recording, etc. In (at least) countries adhering to the Berne Convention, copyright automatically starts covering the work upon the original creation and fixation thereof, without any extra steps. While creation usually involves an idea, the idea in itself does not suffice for the purposes of claiming copyright.
Confidentiality and nondisclosure agreements are legal instruments that assist corporations and individuals in keeping ideas from escaping to the general public. Generally, these instruments are covered by contract law.