How can you tell whether a politician is causing harm on purpose?

Start by separating the outcome from the intention. A policy can cause serious harm without that harm being its purpose. To argue intent, you’d want evidence such as clear statements, reliable records of decision-making, or a repeated pattern where the damaging result appears to be the goal, not just a foreseeable cost.

It also helps to ask what other explanation fits the same evidence. If a policy serves an ideological or political objective despite its costs, that’s different from deliberately seeking the costs themselves.

Political incentives can explain a lot without requiring a plan to wreck the country. A leader may push policies that energize supporters or fulfill campaign promises, while accepting consequences that critics consider damaging. Staying within the limits of political support doesn’t, by itself, show that the underlying aim is sabotage.

I’d be careful about treating every bad decision as evidence of a hidden strategy. Incompetence, conflicting priorities, and willingness to take risks can all produce damaging results. The strongest case for deliberate harm would need more than “this seems irrational” or “the outcome is bad.”