NaivePhysics is naive because it is based on CommonSense rather than DirectObservation or ConcreteRationality.

That's not a definition, but I wanted to frame that thought before I gave the ''real'' definition. I'm having some difficulty even thinking about NaivePhysics without resorting to negatives like "without", "uninformed", and "ignorant" (I know, "ignorant" isn't in and of itself negative. But that's a topic for another page). How about:

NaivePhysics is the practice of explaining physical phenomena in terms of everyday experience.

-- LaurencePhillips

'''Whereas the root principle of "Cartoon Physics" is "Physical laws don't apply until you notice them"''' http://www.tfportal.net/gfx/content/tf2/guidepics/surfguide/Koyote.jpg

See http://en.wikipedia.org/wiki/Cartoon_physics for more examples. I'd change the anvil one to read, "Living beings fall faster than anvils", but it's a quote.

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NaivePhysics is also called "Folk Physics", analogously to "Folk Botany", "Folk Biology", "Folk Psychology", etc. These refer to the beliefs and practices of people based on innate intuitions, personal observations, and cultural heritage, but not related to technology-based scientific study.

Folk and scientific studies are not necessarily in conflict. Botany has frequently benefited from the expertise of e.g. natives in the Amazon, and conversely, studies have shown that non-technological cultures assessment of categorizing plants and animals is a very close match to modern scientific approaches, at the level of the 3 kingdoms plus to some extent order, and to a large extent genus and species, which has been argued to be the most important levels of taxonomy anyway, with other levels more arbitrary.

It is also a widespread belief that FolkPsychology, as practiced by pretty much all humans, may well be superior to supposedly scientific psychology, e.g Freudian analysis. :-)

Folk physics is usually considered to be particularly naive compared with scientific physics, but even this is questionable. The two have different goals. Scientific physics tends to look for universal laws and relationships, whereas folk physics tends to be ultimately rooted in individual survival, and therefore pragmatically assumes as universals things that tend to be near-universal for humans, such as omnipresent friction, approximately Standard Temperature and air Pressure conditions, 1 g, etc.

The infamous examples of historical figures whose NaivePhysics lead them to believe that e.g. arrows shot at a 45 degree angle would rise in a straight line, turn and then fall along the reflected 45 degree angle straight line tend to be considered humorously and absurdly naive, but there is reason to think that these examples are aberrations on the part of individuals who were actually ignoring widespread Folk Physics and instead focusing on an idiosyncratic "logical" train of thought on the subject.

As a human universal, people are quite, quite good at gauging trajectories when e.g. throwing a rock or catching a rock, and such universally strong performances show that innate Folk Physics of trajectories is not as naive as some of the historical illustrations suggest. -- DougMerritt

''I think that people '''use''' physics easily, but have trouble '''describing''' physics accuratly. Like many kids, who know that to jump a chasm, one must run fast and jump high, but if asked, will probably describe a failed jump in terms that resemble a Warner Bros cartoon - straight line travel to a stop, then a vertical plummet.'' -- PeteHardie

It's true that there's a sharp difference between procedural knowledge and declarative knowledge; they're all but unrelated in the brain.

However, for one thing, expert Folk Physics is not a matter of tabula rasa perceptions of new-born babies, nor even a question of "kids say the darndest things"; it includes adult experts with long personal observation and transmission of cultural knowledge. Any human who closely observed someone else throwing a rock or a spear would observe that it follows a curve, not straight line segments, and therefore, there is immediate reason to suspect that most cultures throughout history were aware of this.

So there's every reason to think that a fair amount of the comments in the literature about the naivety of Naive Physics were themselves remarkably naive (and obtuse) comments.

Note also the contrast with the admirably expert skills demonstrated in Folk Botany and Folk Biology; that's suspicious as well.

It is of course interesting to find out how individuals perceive things as they go through various stages of brain development and cultural inheritance in childhood, but that most certainly is not the only, or even primary, area of NaivePhysics - and furthermore, such things are notoriously slippery, as witness the modern refinements to Piaget's observations about children's perception of the constancy of volume at different stages of development.

Also we should not forget that some fairly remarkable NaivePhysics skills have been demonstrated even in newborne babies, such as strong expectation of conservation of objects, conservation of motion, etc. -- DougMerritt
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See also: ScienceShouldBeEasy