Scientific risk evaluations are constructed by specific evidence, value judgements
and biological background assumptions. The latter are the framework-setting
suppositions we apply in order to understand some new phenomenon. That
background assumptions co-determine choice of methodology, data interpretation,
and choice of relevant evidence is an uncontroversial claim in modern basic science.
Furthermore, it is commonly accepted that, unless explicated, disagreements in
background assumptions can lead to misunderstanding as well as miscommunication.
Here, we extend the discussion on background assumptions from basic science to the
debate over genetically modified (GM) plants risk assessment. In this realm, while the
different political, social and economic values are often mentioned, the identity and
role of background assumptions at play are rarely examined. We use an example from
the debate over risk assessment of stacked genetically modified plants (GM stacks),
obtained by applying conventional breeding techniques to GM plants. There are two
main regulatory practices of GM stacks: (i) regulate as conventional hybrids and (ii)
regulate as new GM plants. We analyzed eight papers representative of these positions
and found that, in all cases, additional premises are needed to reach the stated
conclusions. We suggest that these premises play the role of biological background
assumptions and argue that the most effective way toward a unified framework for risk
analysis and regulation of GM stacks is by explicating and examining the biological
background assumptions of each position. Once explicated, it is possible to either
evaluate which background assumptions best reflect contemporary biological
knowledge, or to apply Douglas' 'inductive risk' argument.