Hypothesis

This is a central feature of scientific method, specifically as the key element in the hypothetico-deductive model of science (Chalmers, 1999). Variations on this model are used throughout the sciences, including social science. Hypotheses are statements derived from an existing body of THEORY that can be tested using the methods of the particular science. In chemistry or psychology, this might be an experiment, and in sociology or political science, the social survey. Hypotheses can be confirmed or falsified, and their status after testing will have an impact on the body of theory, which may be amended accordingly and new hypotheses generated. Consider a simplified example: Classical migration theory states that economic push and pull factors will be the motivation for migration, and agents will have an awareness of these factors. From this, it might be hypothesized that migrants will move from economically depressed areas to buoyant ones. If, upon testing, it is found that some economically depressed areas nevertheless have high levels of inmigration, then the original theory must be amended in terms of either its claims about economic factors, or the agents' knowledge of these, or possibly both.

Rarely, however, is it the case that hypotheses are proven wholly right (confirmed) or wholly wrong (falsified), and even rarer that the parent theory is wholly confirmed or falsified. Through the second half of the 20th century, there was a great deal of debate (which continues) around the degree to which hypotheses and, by implication, theories can be confirmed or falsified. Karl Popper (1959) maintained that, logically, only a falsification approach could settle the matter, for no matter how many confirming instances were recorded, one can never be certain that there will be no future disconfirming instances. Just one disconfirming instance will, however, demonstrate that something is wrong in the specification of the theory and its derived hypothesis. Therefore, in this view, scientists should set out to disprove a hypothesis.

Falsification is logically correct, and its implied skepticism may introduce rigor into hypothesis testing, but in social science in particular, hypotheses cannot be universal statements and are often probabilistic. In the example above, no one would suggest that everyone migrates under the particular given circumstances, but that one is more or less likely to migrate. Indeed, in many situations, the decision as to whether one should declare a hypothesis confirmed or falsified may be just a matter of a few percentage points' difference between attitudes or behaviors in survey findings.

Hypotheses can be specified at different levels. Research hypotheses are linguistic statements about [Page 468]the world whose confirmation/falsification likewise can be stated only linguistically as “none,” “all,” “some,” “most,” and so on. In qualitative research, a hypothesis might be framed in terms of a social setting having certain features, which, through observation, can be confirmed or falsified. However, in survey or experimental research, hypothesis testing establishes the statistical significance of a finding and, thus, whether that finding arose by chance or is evidence of a real effect. A null hypothesis is stated—for example, that there is no relationship between migration and housing tenure—but if a significant relationship is found, then the null hypothesis is rejected and the alternative hypothesis is confirmed. The alternative hypothesis may be the same as, or a subdivision of, a broader research hypothesis (Newton & Rudestam, 1999, pp. 63–65).

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