The fundamental notion that underlies all scientific investigation is the idea that claims about knowledge have to be grounded in observations of the real world. This entails that the observations be carefully and systematically made, that theories be formulated so as to be consistent with these observations, and that theoretical claims be adjusted or abandoned if they are inconsistent with or contradicted by such observations.
Since different observers sometimes look at things in different ways (particularly when observing social and psychological phenomena), some approaches to science adhere to highly specific rules and procedures in order to ensure that everyone can be relatively certain about what has been observed and what it means. These rules and procedures define science in the strictest sense. They require, for example, that observations be defined in operational terms (that is, in terms of specific operations, equipment, and measurements), that theoretical terms be similarly exactly defined, that specific hypotheses be derived from such theories and tested under controlled conditions, and that these hypotheses be unambiguously accepted or rejected depending on the results. It is assumed that the results of the investigation will be replicable. That is, it is assumed that other observers studying the identical phenomenon and following identical procedures will obtain identical results. It is also therefore assumed that the application of such techniques will lead to knowledge that is generalizable and nomic (law-like), at least in a statistical sense; and it is ordinarily assumed, as well, that such knowledge is ultimately related to, and consistent with, the underlying causal regularities discovered in the natural sciences ("methodological naturalism"). Under this conception of science, any attempt to gather knowledge that fails to meet these strict requirements is subject to severe doubts that obligate its proponents to explain any discrepancies or ambiguities, and/or to revise or reject the theories or hypotheses associated with it.
The problem with this approach, however, is that when it is applied to social and psychological phenomena it forces us to define these phenomena in such a narrow and specific way that research based on these definitions often seems artificial, dubious, and disconnected from ordinary experience. This is what usually attracts people to the qualitative techniques described on the previous page. Since qualitative techniques like in-depth interviewing and naturalistic observation do not require researchers to follow the rules and procedures described in the second paragraph above, these techniques give us a great deal of power to investigate human experience as it is actually lived; but they also strike many people as unscientific since they seem to abandon what many believe to be the core practices of science.
Note, though, that the rules and procedures in the second paragraph above are not the core practices of science. The real core practices of science are the ones described in the first paragraph: the commitment simply to basing knowledge on observable evidence and to adjusting or rejecting claims that are not supported by such evidence. Thus, qualitative research can also be regarded as scientific in this broader sense, for qualitative researchers must base their findings on real observations in the real world and they must be willing to subject both their methods and their findings to close and careful scrutiny, critique and alternate explanations by other researchers, qualitative and quantitative. To put it another way, it means that while qualitative research is not subject to the requirements of science in the narrow sense, it must nevertheless be compatible with the findings of this stricter and more narrow kind of science, including the results of controlled experimentation. This is a crucial point, for it distinguishes qualitative research and other inexact methods from pseudoscience, which generally resists scrutiny and/or maintains its claims even when they are unsubstantiated or contradicted by evidence.
However, as noted above, science in the strict sense was developed in order to ensure relative certainty about our knowledge. It may therefore be wondered what kind of certainty, if any, is possible when we employ qualitative research and other inexact techniques that are allowable under the broader definition of science. I will consider this question on the next page, which concerns the topic of reasoned inquiry.