When to Trust an Expert

The evidence free conclusion of an expert should be trusted only when:

1. No available, well-reasoned argument contradicts the conclusion.
2. The expert has relevant expertise on the issue. 
3. No more competent expert contradicts the expert.

Multiculturalists frequently argue that sex ed teachers should teach their social views without interference from parents. This is the fallacy of faulty expertise. Sex ed teachers have a tiny bit of expertise in health, anatomy, and physiology. Sexual ethics is not their field of expertise, and well-reasoned arguments against sexual degeneracy abound. Most parents care more about their childrens' well-being than teachers for kin selection reasons.

Climate scientists are experts on whether climate changes exist. They are not experts on policy responses to climate change.

English teachers, experts at prose aesthetics, rank among the most gifted humans at manipulation. They are not experts on logic and ethics, no matter how many vapid, fallacious critical thinking lessons they teach. An event happening in fiction is not evidence to believe a real world conclusion. 

Most social scientists are not competent experts in their own fields of study, in part because the overwhelming majority of social science is junk science. Most philosophers are incompetent at logic and ethics, no matter how much expertise they have at ontology and other issues. 

Virologists and epidemiologists are seldom competent experts about lab leaks.

Politicians, unfortunately, are not legitimate policy experts. Business people are not ethical experts, no matter how successful their careers are.

Circumstantial ad hominem investigations of experts offering weakly supported conclusions are often relevant exceptions to the personal attack fallacy, especially experts from fields riddled with greed, careerism, and groupthink (cough, cough: finance).

When every competent electrician agrees about a wiring connection issue, we have good reason to believe their conclusion, an exception to the fallacious appeal to popularity.

But "trust the science," when more competent experts disagree, is little more than a faith-based slogan.