What usually passes for a scenario today is a discussion about a range of future possibilities with data and analysis. Such a discussion of future research is perfectly fine and should be done but does not constitute a scenario.
A good scenario is a descriptive, written narrative with plausible cause and effect links that connects a future condition with the present, while illustrating key decisions, events, and consequences throughout the narrative. It is a qualitative body including projections and forecasts, while providing specific context values.
Usually, scenarios are given a specific time horizon and subject such as the ‘Social Market Economy of 2035’. A scenario is not a single prediction or forecast, but a way of organizing many statements about the future. It should be sufficiently vivid so that one can clearly see and comprehend the problems, challenges, and opportunities that such an environment would present. A scenario is not a prediction or specific forecast per se; rather, it is an informed description of what might occur and how that could emerge from the present. Scenarios describe events and trends as they could evolve. As such they rarely exist alone, but rather as part of a complementary set of scenarios.
Herman Kahn, system strategist and futurist, argues that scenarios should be judged by their ability to help decision makers make policy now, rather than whether they turn out to be right or wrong. 'Good' scenarios are those that are:
Plausible (a rational route from here to there that makes causal processes and decisions explicit)
Internally consistent (alternative scenarios should address similar issues so that they can be compared)
Sufficiently interesting and exciting to make the future 'real' enough to elicit strategic responses.
Because the future cannot be known, most planners and futurists today reject the idea that planning should be conducted against a single 'most likely' image of the future. Rather, sets of scenarios or shifting or adaptable aspects of future relevant developments should be taken into consideration.
The purpose of scenarios is to systematically explore, create, and test consistent alternative future environments that encompass the broadest set of future operating conditions that the world might plausibly face. Scenarios can help generate long-term policies, strategies, and plans, which help bring desired and likely future circumstances in closer alignment. The process can also expose ignorance; show that we do not know how to get to a specific future or that it is impossible. Furthermore, they serve to bring assumptions to the foreground and serve as a tool to discuss, test and maybe re-evaluate these assumptions.