Two aspects of scenarios are particularly important:
- the distinction between snapshot and sequence scenarios \citep{van_Notten_2003} and
- the distinction between external and strategic scenarios \citep{B_rjeson_2006}.
A basic distinction among scenarios is the distinction between scenarios as snapshots and scenarios as sequences or development paths. \citet{Bishop_2007} call the first category end state or 'day in the life' scenarios, and the second category is titled chain scenarios or future histories. It would perhaps be more appropriate to have separate terms for these types, but both types of scenarios are well represented in futures research and both have important roles.
According to \citet{Bishop_2007}, the Global Business Network method of building scenarios has become dominant and it has somewhat shadowed other scenario techniques. Following this approach, scenarios are conceived as structural descriptions of a future operational environment, focusing on key variables and uncertainties \cite{schwartz1996art}. The aim of scenarios is to impact strategic thinking today and to promote organisational learning \citep{van2009sixth}. \citet[][77--78]{staley2007history} makes the case for structural descriptions most explicitly, arguing that a "scenario is meant to be synchronic rather than diachronic", describing "the rules of a game, rather than [...] the specific sequence of play". In other words, a scenario is conceived as a thick structural description of a future end-state.
Of course, the success of the GBN technique is partly due to the fact that it is an excellent, insightful technique, but partly it is a path-dependent and self-reinforcing development as new futurists are taught the GBN method or a variation of it and they may never get acquainted with alternative approaches. In my view, it is a richness rather than a hindrance that there are many different scenario approaches. The evolution of scenario building should not lead to one dominant approach but to a diversity of approaches.
In this paper, scenarios are considered as sequences of events or paths of development rather than end-points. This is because the perspectives of time, sequence and duration are important in understanding social change from a social scientific perspective \citep{sztompka1993sociology}. The notion of scenarios as sequences goes back to the roots of scenario thinking in Herman Kahn's writings on scenarios \citep{kahn1967year}. Scenario techniques within this tradition include probability trees, sociovision and divergence mapping \citep{Bishop_2007}.
Concerning the second distinction between external/strategic, the arguments in this paper mostly relate to external scenarios, focusing on the developments in the societal surroundings.