[madgar]

You underestimate how deep this goes with the actual public.

My father has been in the GOP base his whole life. The refrain when I challenged his views on science was: "those scientists are all liberals. Why should I believe anything they have to say?"

He encouraged me to study sciences anyway because it offered a better life than his. Now, of course, he explicitly regrets providing me that education, because he sees me as "brainwashed."

[effie]

As it often goes, both extreme political views (liberal pro-science vs. conservative, ignore-science) have some good points to make, and some unjustified beliefs that harm mutual understanding. May I suggest that you do not try to challenge your father's views on scientists directly head-on. Give him an example of a scientist and a contribution that may be interesting on their own. It's much less likely that the refrain will be used to discard your effort. Perhaps tell him about a scientist who wasn't a liberal, perhaps had some similar views as your father has - but still believed in science. Tell him about Teller, who was as far from being a liberal as it goes, pushing for hardline foreign policy and bigger and better nuclear weapons. Still he was a brilliant scientist and he perceived the potential danger of climate change due to fossil fuels already in 50's. Tell him about Fleming, an army doctor who investigated sepsis, discovered pennicilin and helped bring the humanity a cure to many bacterial diseases.

[madgar]

It's not about discarding what every scientist says. It's discarding the scientists that say things incompatible with his political opinions.

If a scientist pursues a line of work that might end up contradicting the GOP party line, they're immediately disqualified as a scientist. To him, that proves the scientist is motivated purely by political or financial gain.