>Honest question: does this also mean that Earth Science departments should go out of their way to hire climate change denialists, and Biology departments should go out of their way to hire creationists and anti-vaxxers?

Absolutely not.

>In my field (Biology) it seems like it'd be almost impossible to find a well-qualified faculty candidate who is an average US conservative without applying some truly outrageous "affirmative action" for conservatives.

Have you considered that your view of an "average" US conservative is incredibly biased by the media you consume and the environment you operate in? And that your incorrect stereotype might be the reason you seem comfortable making arguments against observed discrimination that you would immediately reject if they were applied to other groups?

In the current environment you operate in, would you even know if one of your peers is conservative? Is it safe for them to be "out" about their political beliefs?

> Also, have you considered that academics don't select for liberalism, but liberals select for academia?

I've considered it, but the evidence suggests that discrimination is a better explanation of the facts. Haidt notes that historically most university departments were not the political monocultures they are now. Haidt also responds directly to your criticisms about qualifications and personal preference. I quote:

On intelligence:

"[Are conservatives simply less intelligent than liberals, and less able to obtain PhDs and faculty positions?] The evidence does not support this view… [published studies are mixed. Part of the complexity is that…] Social conservatism correlates with lower cognitive ability test scores, but economic conservatism correlates with higher scores (Iyer, Koleva, Graham, Ditto, & Haidt, 2012; Kemmelmeier 2008). [Libertarians are the political group with the highest IQ, yet they are underrepresented in the social sciences other than economics]"

On self-selection:

"Self-selection clearly plays a role. But it would be ironic if an epistemic community resonated to empirical arguments that appear to exonerate the community of prejudice—when that same community roundly rejects those same arguments when invoked by other institutions to explain the under-representation of women or ethnic minorities (e.g., in STEM disciplines or other elite professions). [Note: we agree that self-selection is a big part of the explanation. If there were no discrimination and no hostile climate, the field would still lean left, as it used to. But it would still have some diversity, and would work much better.]"

Given that there's ample evidence of explicit evidence of discrimination against conservatives in academia, that is a straightforward explanation for the disparity we observe.

I'd highly recommend reading the three papers I've linked in this thread for an overview of this issue which goes deeper than the "conservatives don't want to be in academia and even if they did, they'd be too stupid to contribute anyways" idea.

>have you considered that there are certain truths in these fields that simply contradict the conservative worldview?

Have you considered that every ideological system has its own blindspots, and that the mechanisms of peer-review breakdown in an ideological mono-culture? Consider that some of the social scientific concepts facing the toughest scrutiny in the ongoing replication crisis are concepts beloved by a certain ideological group, like implicit bias and stereotype threat[0]? And that ideological blindspots can negatively affect the search for scientific truth, both by embedding values in the research that's conducted and by the absence of research in other directions? That these ideological blindspots might even exist in your own field of biology?

[0]: http://heterodoxacademy.org/2016/02/23/are-most-published-so...