The Garbage Can Model is a theory within the science of public administration that explains organizational decision making from a systemic-anarchic perspective.
It was developed in reference to "ambiguous behaviors", i.e. explanations/interpretations of behaviors which at least appear to contradict classical theory. The Garbage Can Model was greatly influenced by the realization that extreme cases of aggregate uncertainty in decision environments would trigger behavioral responses which, at least from a distance, appear "irrational" or at least not in compliance with the total/global rationality of "economic man" (e.g. "act first, think later"). The Garbage Can Model was originally formulated in the context of the operation of universities and their many inter-departmental communications problems.
The Garbage Can Model tried to expand organizational decision theory into the then uncharted field of organizational anarchy which is characterized by "problematic preferences", "unclear technology" and "fluid participation". "The theoretical breakthrough of the Garbage Can Model is that it disconnects problems, solutions and decision makers from each other, unlike traditional decision theory. Specific decisions do not follow an orderly process from problem to solution, but are outcomes of several relatively independent stream of events within the organization." (Richard L. Daft, 1982, p.139).
The model was based on a computer simulation coded in FORTRAN. The coding was included as an appendix in the original 1972 article , which was the first time a coding sequence appeared in a social science article.
Four of those streams were identified in Cohen, March & Olsen's original conceptualization:
Problems require attention, they are the result of performance gaps or the inability to predict the future. Thus, problems may originate inside or outside the organization. Traditionally, it has been assumed that problems trigger decision processes; if they are sufficiently grave, this may happen. Usually, however, organization man goes through the "garbage" and looks for a suitable fix, called a "solution".
They have a life of their own. They are distinct from problems which they might be called on to solve. Solutions are answers (more or less actively) looking for a question. Participants may have ideas for solutions; they may be attracted to specific solutions and volunteer to play the advocate. Only trivial solutions do not require advocacy and preparations. Significant solutions have to be prepared without knowledge of the problems they might have to solve.
There are occasions when organizations are expected (or think they are expected) to produce behavior that can be called a decision (or an "initiative"). Just like politicians cherish "photo opportunities", organization man needs occasional "decision opportunities" for reasons unrelated to the decision itself.
They come and go; participation varies between problems and solutions. Participation may vary depending on the other time demands of participants (independent from the particular "decision" situation under study). Participants may have favorite problems or favorite solutions which they carry around with them...
It was suggested that organizations tend to produce many "solutions" which are discarded due to a lack of appropriate problems. However problems may eventually arise for which a search of the garbage might yield fitting solutions.
Probably the most extreme view (namely that of organizational anarchy) of the Carnegie School. Organizations operate on the basis of inconsistent and ill-defined preferences; their own processes are not understood by their members; they operate by trial and error; their boundaries are uncertain and changing; decision-makers for any particular choice change capriciously. To understand organizational processes, one can view choice opportunities as garbage cans into which various kinds of problems and solutions are dumped. The mix of garbage depends on the mix of labeled cans available, on what garbage is currently produced and the speed with which garbage and garbage cans are removed.