Informed people should be absolutely allergic to the suggestion that someone promoting or opposing a given policy does do because they have malicious intent (and frankly, be suspicious of suggestions that someone are doing it because they have particularly pure intent).
This. Once you dig into the research, or just have a lot of conversations with people who have opposing viewpoints, you realize that the vast majority i.e. 99% of people have the same goals and well-meaning intentions. For example, conservatives and democrats both want to maximize human flourishing, they both want people to be happy, they want to prevent poverty and provide people with an environment that maximizes well being for everyone. All sides come from this same starting place morally.
Its on the best pathway to achieve our common goals that people differ in opinions. This is why I always advocate for more scientific method in politics and governmental processes, we need better data and models and we need to test those models so we can better discern which paths are best towards reaching our common goals.
Suppose counterfactually that one side or both sides are in fact motivated by malice. Do you think you would be able to detect this by examining their officially stated desires and morality?
Nearly all people want to think of themselves as morally good and are good at telling stories (often to themselves) about why they are good. This doesn't provide strong evidence that they are in fact good.
Insofar as you can define a measurement for malicious intent, you could detect this. The set of measurements you define might not tell you everything you want to know about malicious intentions but they would give you a decent approximation.
For example:
Image we have a controlled random study, we have two groups A and B. We show both groups a medication K, and give group A a motivation (perhaps monetary say $10) for K to be approved, we give an equal weighted motivation $10 to group B for not approving. Then we show both groups information showing that K has some detrimental effect. Observe outcomes, and those who approve for the monetary motivation would be displaying "malicious intent" as defined by the measurements in this study.
Generalizing from studies, however, to what particular persons in political parties at a particular point in time are thinking is something for historians or debaters and a set of methods I am unfamiliar with, outside of a general knowledge of the dialectic.
Your experiment won't measure evilness, perhaps something along the lines of honesty when faced with conflicting incentives (which of course is a desirable trait in leaders, political and otherwise). But what if one of the subjects in group A needs the money to buy a loaf of bread for their starving family, to illustrate using a favourite ethical dilemma? What do you do if a given policy will benefit yourself, but you know for certain that it's a right and good policy?
My experiment was not intended to measure evilness but rather to give an example of a general approach to the problem, and was for measuring malicious intent. Regardless, given time I'm sure we could come up with much better experiments for studying both.
You're right though at what you are getting at, and I think the underlying idea here is that there is a continuous scale from bad (0) to good (1) for any given action/policy, where given additional context our internal moral barometer can move across this domain as well as an independent societal human flourishing barometer which measures the broader repercussions of the action/policy.
Honestly, I do not know enough about ethics or research in this general area to have a truly insightful conversation on this topic.
I'd just like to add that 1) I think good and evil are so broad in their scope that we'd be virtually forced to break them into separate definitions and measurements and study these constituent parts if we wanted to understand the general concepts and 2) we'd need to make a clear distinction between what humans perceive as good/evil in each context vs. what has good/evil repercussions at different levels (individual/familial/societal) based on measurements of brain states, pain/suffering, and human flourishing.
What matters is if the policy is good.
Nice attempt to apply the media tactics to the model itself.