what are theories

what are theories

Part of the Darwin exhibition.
A theory not only explains known facts; it also allows scientists to make predictions of what they should observe if a theory is true. Scientific theories are testable. New evidence should be compatible with a theory. If it isn’t, the theory is refined or rejected. The longer the central elements of a theory hold–the more observations it predicts, the more tests it passes, the more facts it explains–the stronger the theory.

The chapter discusses the “received view” on the role of theories in empirical science. It discusses those theories that are to be thought of as “partially interpreted calculi” in which only the “observation terms” are “directly interpreted”. The view divides the nonlogical vocabulary of science into two parts: observation terms and theoretical terms. This division of terms that belongs to two classes is allowed to generate a division of statements into two classes, such as observational statements and theoretical statements. A scientific theory is conceived of as an axiomatic system that may be thought of as initially uninterpreted and that gains empirical meaning as a result of a specification of meaning for the observation terms alone. It should be noted that the dichotomy under discussion in the chapter is intended as an explicative not a stipulative one. That is, the words “observational” and “theoretical” are not having arbitrary new meanings bestowed upon them; instead, pre-existing uses of these words (especially in the philosophy of science) are presumably being sharpened and made clear.
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There are several theories and models that support the practice of health promotion and disease prevention. Theories and models are used in program planning to understand and explain health behavior and to guide the identification, development, and implementation of interventions.
When identifying a theory or model to guide health promotion or disease prevention programs, it is important to consider a range of factors, such as the specific health problem being addressed, the population(s) being served, and the contexts within which the program is being implemented. Health promotion and disease prevention programs typically draw from one or more theories or models.

What are theories
Of course, scientific theories are meant to provide accurate explanations or interpretations of phenomena. But there must be more to it than this. Consider that a theory can be accurate without being very useful.
To say that expressive writing helps people “deal with their emotions” might be accurate as far as it goes,

Skinner, B. F. – operant conditioning
Milgram, Stanley – obedience experiment

References:

http://www.sciencedirect.com/science/article/pii/S0049237X09705919
http://www.ruralhealthinfo.org/toolkits/health-promotion/2/theories-and-models
http://www.opentextbooks.org.hk/ditatopic/35368
http://libguides.norquest.ca/psych/psych_famous
http://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2162-6057.1983.tb00970.x