Most of the literature on hiring is about technical ability, and indeed that's important. But no job is solely technical: there are communication and cooperation aspects as well. The output of a group is not simply the sum of its components.
In that regard I have a thesis: the most important thing about hiring is to avoid the fash. Fascist sympathisers are toxic to the collective organism and you do not want them on your team. The tricky thing is honing your fashdar to suit the purpose.
I am currently in Oxford for ICFP, one of the most prestigious conferences of my field (programming languages). I came to be refreshed with new ideas and to maintain contacts, for collaboration and also for future hires. This evening I was out with a group of folks, and the topic of conversation for much of the evening was the abstract value of free speech versus anti-fascist activity.
Unfortunately, one participant was stuck on free speech side of the debate. All day the conference has been doing logical programs and term equivalence, but somehow this person didn't deduce the result "free speech fundamentalism == fash", at least within the current evaluation context.
In the US we are raised to see speech as an axiom. As such it must be taken on faith, and such faith is only present in people not physically threatened by the axiom. For example, as an immigrant to France, speech against immigrants in France is not simply an abstract topic to me. It means that my existence does not have the same value as someone that was born there. More broadly it also applies to second-generation immigrants, or to people of color, as whiteness is also part of what it means to be a native French person. Treating the speech of all equally is probably a good ideal among speakers of equal power, but in the current context, enshrining "free speech" as a Trump card of social value is fash. Saying "Latino people are lazy" is obviously more threatening to Latinos than "white people are lazy" is to whites (ed: not that these sets are disjoint!); but under the "free speech" evaluator, these terms are equivalent. "Free speech" as an abstract interpreter of value is too abstract.
I thought with this person we had a good discussion trying to get them closer to a justice-affirming perspective, but in the end they turned out to also believe that women were predisposed to not be good computer scientists -- "genetic differences", they said. Never mind that CS was women's work until it became high-status, and this after the whole discussion of the effects of speech; it does not take an abstract interpretation specialist to predict the results of this perspective on the future gender composition of the industry, not to mention the concrete evaluation of any given woman.
I will admit that I was surprised at the extent to which men's-rights-activist and racist talking points had made it into their discourse, and the way the individualist edifice of their world-view enabled their pre-fascist ideas. I use the term advisedly; the effects of advocating these views are prior to fascism.
My conclusion from the interaction is that, now more than ever, when it comes to future collaborators, in any context, it is important for anyone for whom justice matters to probe candidates deeply for fascist tendencies. If they show a sign, pass. Anti-immigrant, anti-woman, anti-queer, and anti-black behaviors and actions often correlate: if you see one sign, often there are more underneath. Even if the person claims to value egalitarianism, the perspectives that guide their actions may not favor justice in your organization. In retrospect I am glad that I had this interaction, simply for the purpose of knowing what to filter out the next time I am in a hiring decision.