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Five Objections to Decision Science in Conservation

By Hugh Possingham

What are the main objections to decision science, and why they are wrong?

Since 1994 I have given more than 300 seminars to every manner of audience on how decision science can inform environmental management. In that time I’ve received a wide range of arguments about why decision theory tools should not be applied to conservation problems. Here I review the most common objections and suggest that they are wrong, but I’m going to go further and say that natural resource management in Australia must embrace the tools of decision science.

It’s important to dispel the myths surrounding these objections. As a nation we’re failing hopelessly to secure Australia’s biodiversity. In recent decades the Australian government has spent billions of dollars on natural resource management, and in most cases the allocation decisions behind this expenditure have been ad hoc and opaque.

So, here are the five most common objections with their strengths and weaknesses.

Objection 1. It’s based on models: “This is all ecological modelling and ecological models are all wrong.”
Well, of course this is correct: all models of everything are wrong. The only perfect model for something is the thing itself, and then it ceases to be a model. However, models are our only way of predicting the future, and if you are a manager you must be predicting the future as a consequence of actions – otherwise you could never take an action. Hence, by definition, every manager, indeed every human being, is a modeller – it is just that most don’t use maths.

Objection 2. It’s all economics: “The principles of decision theory are founded in economics, and it is economics that has made a mess of the world.”
The tools we use are designed to solve mathematically well-defined problems. These tools are used by engineers, mathematicians and economists. The tools of decision science drive most small-scale decisions from how to supply troops in a battle, to oil refineries ordering crude supplies, to airline companies devising their plane schedules.

One aspect of decision science that really irks some people (and is very much an economic way of thinking) is that we generally need to give every value a numerical quantity. Typically economists deal with money, but environmental values often deal with things that at first glance seem harder to quantify – threatened species, ecosystem services and social values. However, with thought, most can be quantified, albeit with some uncertainty and they do not have to be turned into dollars and cents for them to be used in decision science.

Objection 3. It’s too cumbersome: “Using decision theory takes too long. We haven’t got the time or money to use these approaches.”
In cases where decisions are small and once-off, you are correct: spending money on using or developing a decision theory tool is like cracking a nut with a steam roller. However, tools are becoming easier to use, and many environmental management problems involve millions of dollars. In most cases the use of an approach or tool will save money and biodiversity. Or, more uncharitably, if you are not using the most appropriate decision theory tools you may well be consigning some biodiversity to extinction!

Objection 4. It’s a black box: “Nobody wants to have a computer tell them what to do.”
You are correct, which is why we always say that these approaches and tools inform decisions rather than make decisions. There are invariably considerations that cannot be accommodated in the formulation of a complex socio-ecological problem – so we need some wiggle room.

However, as far as black-boxes are concerned – so what? What percentage of the public know how planes fly, or hand calculators calculate, or microwaves cook?

Objection 5. There’s too much uncertainty: “There is too much uncertainty and risk to use a decision theory approach.”
Uncertainty and risk are rife in ecological systems – and we face it far more than, say, an engineer (but no more than economists or doctors). Fortunately mathematicians have many ways of rigorously accounting for uncertainty in decision-making – indeed, if a system has a lot of randomness then it is even more important to take a formal quantitative decision-making approach.

So there are “my” five objections to decision science, and I’d describe them all as myths that the nation can no longer afford to accept. After peddling the decision-theory message for 20 years, I think the message is unanimous and unambiguous – it is now the responsibility of managers and policy-makers to make use of the best available science and tools.

Hugh Possingham is the Director of the ARC Centre of Excellence for Environmental Decisions, and is based at the University of Queensland.