Analysis of Uncertainty, Structural Error, and Reachable
Futures. There has always been uncertainty; and always will
be. The advent of its formal analysis is a sign of a maturing
subject. Two sea-changes of outlook over the past two decades,
within the analysis of uncertainty in environmental stewardship,
are striking. First, there has been a shift away from the presumption
of a search for the ultimate truth of a singular model structure
just one (and only one) approximation of the way things
happen. Second, there has been a shift away from the singularity
of what the one (and only) decision-maker might want of the
future, to the plurality of what the people want (and do not
want). We acknowledge that considerations of the quantitative
aspects of uncertainty attaching to the former (crudely stated
as Uncertainty{Computational Model}) may be dwarfed by the qualitative
aspects attaching to the latter (i.e., Uncertainty{Human Behavior})
and befuddled by its sheer unpredictability. Yet it would be
unprofessional of us to put aside the analysis of Uncertainty{Computational
Model} because of this. We move forward accordingly, thus, now
expecting there to be structural change, especially over the
increasing spans of our forecasting (and observational) horizons,
and structural uncertainty/error, possibly expressed as a plurality
of candidate model structures populated by multitudes of candidate
parameterizations. Can we, then, detect structural change in
the presence of so much confounding uncertainty? Can we characterize
structural error/uncertainty and account for its consequences
in any forecasts? Should we try to resolve such structural uncertainty,
through model structure identification? Or is the path forward
to be essentially pragmatic: accept the uncertain empirical
record; accept the ambiguities of interpreting the past through
a multiplicity of candidate model structures; generate ensembles
of forecasts shot through with uncertainty; and act when the
preferred course of action still emerges as "robustly preferred"
above the fog of all the uncertainty? These questions, whose
logic flows from the past and into the future, are worthy of
sustained attention. But we know from adaptive community learning
and the inverse approaches of Sustainability Science that this
logic can be turned around: to start from the plurality of people's
hopes and fears for the future (of their cherished piece of
the environment), to assess their reachability (their plausibility/implausibility),
and to identify the few, key, scientific uncertainties requiring
the purchase of more science because the coming of the
more reachable futures, or more apocalyptic futures, hinges
crucially upon them, all the gross uncertainty notwithstanding.
Would purchase of the same key pieces of new science, in the
here and now, emerge from evaluating the democratic plurality
of what the people want, across the generations into the distant
future? We have achieved proof-of-concept for the associated,
core, computational development. It rejoices in the acronym
of RIMME (or Random-search Inverse Methodology for Model Evaluation).
It seems, remarkably, to be as relevant to the analysis of reachable
futures as it is to the analysis of uncertainty and sensitivity
in the VHOMs (very high order models) of predictive, multi-media
exposure assessments, and to assuring the quality of those VHOMs
as tools designed to fulfil such predictive tasks.