Pseudoscience is distinguishable from protoscience by reviewing its use of the scientific method. Protoscience may be defined as speculation or hypothesis which has not had time to be tested adequately by the scientific method. The testing of pseudoscience is characteristically wanting, occasionally untestable, and frequently unresponsive to accepted means; accordingly, scientific methods often fail to disprove pseudoscientific hypotheses (particularly untestable claims).
The boundaries between pseudoscience, protoscience, and "real" science are often unclear. Many people have tried to offer objective criteria for the term, with mixed success. Oftentimes the term is used simply as a pejorative to express the speaker's low opinion of a given field, regardless of any objective measures.
If the claims of a given field can be tested it may be real science, however odd or astonishing. If they cannot be tested by any means imaginable it is likely pseudoscience. If the claims made are inconsistent with experimental results or established theory, it is often presumed to be pseudoscience.
In other circumstances it may be difficult to distinguish which of two opposing "sciences" are valid; for example, both the proponents and opponents of the Kyoto Protocol on global warming have recruited the help of scientists to endorse contradictory political goals. This enlistment of science in the service of politics is sometimes called "junk science".
Such fields as acupuncture and lucid dreaming may be categorized as protosciences; there is a reasonable expectation that when they are experimentally examined, the results may be such as to qualify them as science.
Typically, pseudoscience fails to meet the criteria laid down by the scientific method in one or more of the following rules of thumb:
Pseudoscience is distinguished from Revelation, Theology or Spirituality in that it claims to offer insight into the physical world by 'scientific' means (i.e., means in accordance with the scientific method). Systems of thought that rely upon "divine" or "inspired" knowledge are not considered pseudoscience if they do not claim to be scientific.
Motivations for the advocacy or promotion of pseudoscience range from simple naivety about the nature of science or the scientific method, to deliberate deception for financial or other benefit.
Some people consider some or all forms of pseudoscience to be harmless entertainment. Others, such as science writer Richard Dawkins, consider all forms of pseudoscience to be harmful, whether or not they result in immediate harm to their followers.
After more than a century of active dialogue, the question of what marks the boundary of science remains fundamentally unsettled. As a consequence the issue of what constitutes pseudoscience continues to be controversial. Nonetheless, reasonable consensus exists on certain sub-issues. Criteria for demarcation have traditionally been coupled to one philosophy of science or another. Logical positivism, for example, espoused a theory of meaning which held that only statements about empirical observations are meaningful, effectively asserting that statements which are not derived in this manner (including all metaphysical statements) are meaningless. Later, Karl Popper attacked logical positivism and introduced his own criterion for demarcation, falsifiability. This in turn was criticised by Thomas Kuhn, and also by Popper supporter Imre Lakatos who proposed his own criteria that distinguished between progressive and degenerative research programs.
Kuhn has proven hugely influential in the philosophy of science, and is often connected with what has been called postpositivism[?] or postempiricism[?]. Kuhn divided the process of doing science into two different endeavors, which he called normal science and extraordinary science. The process of normal science is what most scientists do while working within the current accepted paradigm of the scientific community, and within this context Popper's ideas on falsification as well as the idea of a Scientific method still have some currency. However, Kuhn noted that within the process of doing normal science, anomalies are generated, some which lead to an extension of the dominant paradigm in order to explain them (like the idea of Punctuated equilibrium within the paradigm of Evolution), and others for which no satisfactory explanation can be found within the current paradigm. When enough of these anomalies have accumulated, some scientists begin to participate in the activity of extraordinary science. It is at these moments that new paradigms are created and Paradigm shifts occur (such as the introduction of Thermodynamics, Newtonian mechanics, the Theory of Evolution, etc.)
The process by which Kuhn says a new paradigm is accepted by the scientific community at large does indicate one possible demarcation between science and pseudoscience. Richard J. Bernstein[?] reads Kuhn as saying that a new paradigm is accepted mainly because it has a superior ability to solve problems that arise in the process of doing normal science. That is, the value of a scientific paradigm is its predictive power and its ability to suggest naturalistic solutions to new problems while continuing to satisfy all of the problems solved by the paradigm that it replaces. Pseudoscience can then be said to be demarcated by a failure to provide such naturalistic explanations, which leads to the labeling of any theory represented as science and appealing to metaphysical explanations for natural phenomena as a pseudoscientific idea.
There has been a post-Kuhn trend to downplay the difference between science and pseudoscience. Paul Feyerabend has even gone so far as to claim that there can be found no method within the history of scientific practice which has not been violated at some point in the advancing of scientific knowledge. Both Lakatos and Feyerabend suggest that science is not an autonomous form of reasoning -- but is inseparable from the larger body of human thought and inquiry. If so, then the questions of truth and falsity, and correct or incorrect understanding are not uniquely empirical. Many meaningful questions can not be settled empirically -- not only in practice, but in principle.
The problem of demarcation is considered solved by some, for others there is no such thing as an autonomous scientific method, no definitive philosophy of science and no clear and agreed-upon distinction between science and pseudoscience.
Examples of fields of knowledge that many consider to varying extents to be pseudoscientific include (alphabetically):
Pseudoscientific medical practices are often quite popular, in part because they often work, possibly due to the placebo effect. Many pseudosciences are associated with the New Age movement and there is a tendency to improperly associate all practices of the "New Age" with pseudoscience.
There are also young fields of science that are sometimes frowned upon by scientists from established fields, primarily because they are speculative in nature:
These fields are not considered pseudoscientific or protoscientific by most scientists, though, and they are studied at many universities and specialized institutes. SETI and CETI advocates do generally not claim that extraterrestrials exist, although most consider the possibility likely (see Drake equation). There is controversy in biology about whether evidence of extraterrestrial microbial life has been found (fossilized in meteorites and as part of the Viking program's exobiology experiments).
Certain "watchdog" groups, such as CSICOP, have released statements expressing concern about the apparent growing popularity of pseudoscience, especially when it applies to scientific fields that are intended to save people's lives. A number of self-proclaimed alternative medicine treatments have been designated pseudoscience by critics, largely because some of these methods inspire false hope in terminally ill patients, and end up costing large amounts of money without actually providing any real benefit, treatment, or cure for various ailments.
There is a subset of what is often called pseudoscience which differs from what has been here termed pseudoscience. Most of these are mathematically based, and the problems are often phrased with tempting simplicity. They often live in a closed system of assumptions and premises, and depend on a faulty interpretation of the rules of that system. While pseudosciences have merely failed to prove themselves true, these undertakings can be proven impossible.
The ancient geometric problems of trisecting an angle using only straightedge and compass, and of drawing a square with the same area as a given circle (or "squaring the circle") are examples of this kind of problem. Inventions purporting to illustrate perpetual motion also fall into this group. The latter appears with such frequency that the U. S. Patent Office has a policy not to consider patent applications of this sort.
Because its success does not depend on empirical evidence from the "real" world, some scientists do not consider mathematics to be a science. In that context a violation of the rules of mathematics cannot be pseudoscience.