Starting just with the restricted sense of science as a process for accumulating knowledge, good science and bad science can be objectively measured in terms of efficiency of knowledge acquisition. Upon expanding consideration to technological and social changes made possible by science, science can be subjectively measured in terms of consequences for people that are either good or bad.
In many cases there is considerable debate about what constitutes good and bad science, particularly if some aspect of science benefits some people while harming others.
"Good science" is generally characterized by careful observations, often aided by tools and devices that extend the powers of the human senses.
Much scientific investigation is organized in terms of processes that can be used for testing hypotheses. Many scientific efforts utilize carefully orchestrated experiments that are designed to carefully expose a limited number of particular phenomena to close observation. "Good science" is characterized by objectivity. Individual observers must give fair and unbiased reports of observed phenomena.
Within many scientific disciplines objectivity must also have a social dimension through which many independent observers can all make and reproduce the same observations. In experimental sciences, experiments must usually be shown to be reproducible before the scientific community accepts the results. Even then skepticism is still exercised because people can be misled in their belief that a particular observation is telling us a particular fact about the world.
A unifying feature of good science is consilience between the various scientific sub-disciplines. Consilience is achieved when it is possible to understand chemistry in terms of physics and biology in terms of chemistry and psychology in terms of biology. It is efficient for scientific investigation to divide into specialized sub-disciplines, but these divisions are just for human convenience; scientific knowledge should be a unified whole that reflects the fundamental unity of the physical universe.
Many scientific efforts are oriented around reductionism, the attempt to explain complex phenomena in terms of the interacting components of the system. "Good science" also strives to maintain certain ethical standards. As a human endeavor, science must be integrated into human society and measured against existing ethical standards. If "good science" is done with care, it is open to critical evaluation, is honest, unbiased and deals with the undesirable deleterious consequences that arise out of scientific knowledge.
Bad Science often lacks objectivity. Misapplications of the tools of science to start with a preconceived belief and filter one's observations so as to try to support that belief. Scientists should be self-critical and try to disprove their hypotheses by all available means.
Bad science if often biased either by unrecognized preconceptions or by unreported personal affiliations and agendas. As mentioned above, good science often involves reductionism, but reductionism can fail.
Since good science strives to provide the simplest possible explanations of phenomena (Occam's razor), greedy reductionism is a common feature of bad science. Greedy reductionism is a derogatory label applied to failed efforts in reductionism where a it is incorrectly claimed that simple set of processes can account for or explain some other complex process or set of phenomena.
At the other extreme, bad science can result when it is assumed that the methods of reductionistic analysis will fail to explain certain phenomena, so attempts at reductionism and consilience are not even attempted.
A common form of bad science is pseudoscience. Pseudoscience generally adopts the guise of science, but fails to utilise one or more of the required elements of good science such as skepticism. For example, creation science starts with a conclusion drawn from revelation and interprets data with the assumption that revelation cannot be wrong. Bad science is often unethical and offensive to social standards that apply to all human conduct.
Science can also be judged to be bad when it results in deleterious consequences. Some philosophers of science insist that science and scientists must take direct responsibility for regulating the search for knowledge and its practical applications. Science is widely judged to be bad when it is practiced and applied for selfish gain and without correction of deleterious side-effects.Good science
Versions of bad science
Common forms of bad science
Bad science judgements