We define an opinion as a truth-value assignment to arguments featured in a complex debate. Example arguments in case of the Veggie-debate are:
1. <Reduce harmful fats>: Animal fats are unhealthy. Therefore one should reduce the consumption of animal products as much as possible. 2. <Meat dishes are cultural heritage>: Completely abandoning meat and/or animal products would put an end to a centuries-old, cultural tra- dition – the art of cooking. 3. <Organic only for rich people>: Many people cannot afford organic products, especially animal products from sustainable agriculture. Organic foods are on- ly for rich people.
A person can give their opinion by either agreeing to, rejecting or being indifferent towards each of the arguments. For instance, someone could agree to
the first argument, reject the second argument and be indifferent towards the third argument. This opinion can be formalized as a set like this:
A large opinion sample can be gained with the help of an online survey. The survey we constructed from the Veggie-debate can be taken here.
In our survey design, we first elicit the participant’s core opinion by offering a selection of five options:
On the next page, arguments that are logically consistent with the selected option are presented and the participant can indicate for each if (s)he agrees, rejects or is indifferent/has no information about the statement. The last option is the catch-all case where the full set of statements is presented. In case of some of the options, it is possible to give logically inconsistent opinions (for example if a participant agrees that meat consumption should be reduced as much as possible but disagrees that the consumption of animal products should be restricted.) These are not considered on the map.
Creating an opinion graph from the opinion sample}