In philosophy of mind, naïve realism, also known as direct realism, common sense realism or perceptual realism, is the idea that the senses provide us with direct awareness of objects as they really are. Objects obey the laws of physics and retain all their properties whether or not there is anyone to observe them. They are composed of matter, occupy space and have properties, such as size, shape, texture, smell, taste and colour, that are usually perceived correctly.
In contrast, some forms of idealism claim that no world exists apart from mind-dependent ideas, and some forms of skepticism say we cannot trust our senses. Naïve realism is known as direct as against indirect or representational realism when its arguments are developed to counter the latter position, also known as epistemological dualism; that our conscious experience is not of the real world but of an internal representation of the world.
For a history of direct realist theories, see Direct and indirect realism § History.
The naïve realist theory may be characterized as the acceptance of the following five beliefs:
In the area of visual perception in psychology, the leading direct realist theorist was J. J. Gibson. Other psychologists were heavily influenced by this approach, including William Mace, Claire Michaels, Edward Reed, Robert Shaw, and Michael Turvey. More recently, Carol Fowler has promoted a direct realist approach to speech perception.
Searle, for instance, addresses the popular but perhaps mistaken assumption that we can only directly perceive our own subjective experiences, but never objects and states of affairs in the world themselves. According to Searle, it has influenced many thinkers to reject direct realism. But Searle contends that the rejection of direct realism is based on a bad argument: the Argument from illusion, which in turn relies on vague assumptions on the nature or existence of "sense data". Various sense data theories were deconstructed in 1962 by the British philosopher J. L. Austin in a book titled Sense and Sensibilia.
Talk of sense data has been replaced by talk of representational perception in a broader sense, and scientific realists typically assume representational perception. But the assumption is philosophical, and arguably little prevents scientific realists from assuming direct perception, as in direct or "naïve" realism. In a blog-post on "Naive realism and color realism" Putnam sums up with the following words:
"... Being an apple is not a natural kind in physics, but it is in biology, recall. Being complex and of no interest to fundamental physics isn't a failure to be "real". I think green is as real as applehood.".
It is not uncommon to think of naïve realism as distinct from scientific realism, which states that the universe contains just those properties that feature in a scientific description of it, not properties like colour per se but merely objects that reflect certain wavelengths owing to their microscopic surface texture. This lack of supervenience of experience on the physical world has influenced many thinkers to reject naïve realism as a physical theory.
One should add, however, that naïve realism does not claim that reality is only what we see, hear, etc. Likewise, scientific realism does not claim that reality is only what can be described by fundamental physics. It follows that the relevant distinction to make is not between naïve and scientific realism but between direct and indirect realism.
The direct realist claims that the experience of a sunset, for instance, is the real sunset that we directly experience. The indirect realist claims that our relation to reality is indirect, so the experience of a sunset is a subjective copy of what really is radiation as described by physics. But the direct realist does not deny that the sunset is radiation; the experience has a hierarchical structure, and the radiation is part of what amounts to the direct experience.
An example of a scientific realist is John Locke, who held the world only contains the primary qualities that feature in a corpuscularian scientific account of the world (see corpuscular theory), and that other properties were entirely subjective, depending for their existence upon some perceiver who can observe the objects."
The modern philosopher of science Howard Sankey argues for a form of scientific realism which has commonsense realism as one of its foundations.
Realism in physics refers to the fact that physical systems must have definite properties when measured or observed. Physics until the 19th century was implicitly and sometimes explicitly based on philosophical realism.
Scientific realism in classical physics has remained compatible with the naïve realism of everyday thinking on the whole, but there is no consistent way to visualize the world underlying quantum theory in terms of ideas of the everyday world. "The general conclusion is that in quantum theory naïve realism, although necessary at the level of observations, fails at the microscopic level." Experiments such as the Stern-Gerlach experiment and quantum phenomena such as complementarity lead quantum physicists to conclude that "[w]e have no satisfactory reason for ascribing objective existence to physical quantities as distinguished from the numbers obtained when we make the measurements which we correlate with them. There is no real reason for supposing that a particle has at every moment a definite, but unknown, position which may be revealed by a measurement of the right kind .... On the contrary, we get into a maze of contradiction as soon as we inject into quantum mechanics such concepts as carried over from the language and philosophy of our ancestors .... It would be more exact if we spoke of 'making measurements' of this, that, or the other type instead of saying that we measure this, that, or the other 'physical quantity'." It is no longer possible to adhere to both the principle of locality (that distant objects cannot affect local objects), and counterfactual definiteness, a form of ontological realism implicit in classical physics. Some interpretations of quantum mechanics hold that a system lacks an actualized property until it is measured, which implies that quantum systems exhibit a non-local behavior. Bell's theorem proved that every quantum theory must either violate locality or counterfactual definiteness. This claim has given rise to a contentious debate of the interpretation of quantum mechanics. Although locality and 'realism,' in the sense of counterfactual definiteness, are jointly false, it is possible to retain one of them. The majority of working physicists discard counterfactual definiteness in favor of locality, since non-locality is held to be contrary to relativity. The implications of this stance are rarely discussed outside of the microscopic domain but the thought experiment of Schrödinger's cat illustrates the difficulties presented. As quantum mechanics is applied to larger and larger objects, even a one-ton bar, proposed to detect gravity waves, must be analysed quantum mechanically, while in cosmology a wave function for the whole universe is written to study the Big Bang. It is difficult to accept the quantum world as somehow not physically real, so "Quantum mechanics forces us to abandon naïve realism", though it can also be argued that the counterfactual definiteness 'realism' of physics is a much more specific notion than general philosophical realism.
"'[W]e have to give up the idea of realism to a far greater extent than most physicists believe today.' (Anton Zeilinger) .... By realism, he means the idea that objects have specific features and properties -- that a ball is red, that a book contains the works of Shakespeare, or that an electron has a particular spin ... for objects governed by the laws of quantum mechanics, like photons and electrons, it may make no sense to think of them as having well-defined characteristics. Instead, what we see may depend on how we look."
"Virtual realism" is closely related to the above theories.
In the research paper The reality of virtual reality it is proposed that, "virtuality is itself a bona fide mode of reality, and that 'virtual reality' must be understood as 'things, agents and events that exist in cyberspace'. These proposals resolve the incoherences found in the ordinary uses of these terms... 'virtual reality', though based on recent information technology, does not refer to mere technological equipment or purely mental entities, or to some fake environment as opposed to the real world, but that it is an ontological mode of existence which leads to an expansion of our ordinary world."
"The emergence of teleoperation and virtual environments has greatly increased interest in "synthetic experience", a mode of experience made possible by both these newer technologies and earlier ones, such as telecommunication and sensory prosthetics... understanding synthetic experience must begin by recognizing the fallacy of naïve realism and with the recognition that the phenomenology of synthetic experience is continuous with that of ordinary experience."
The alleged necessity to recognize a "fallacy of naïve realism" seems, however, unwarranted. One should not be misled by the word "naïve", for a naïve realist normally understands what a picture is: that the depicted face on a photograph, for instance, is not the real face, and that the things seen on a computer-screen are symbols or electronic depictions, and so on. A majority of the population arguably subscribes to naïve common sense notions of reality, without a recognizable loss in capacity to interact in cyberspace.