How are solo and coauthored publications valued?

[do not understand]

I am starting to realize that co-authored publications sometimes even with 4+ other people in a good journal are valued over solo authored pubs in similarly good or even better journals. If someone has no proven track record of producing solo authored work, especially in this job market, what is the argument used by search committees to assess someone who has one or two solo pubs in respectable journals (not asr/ajs, but top field journals) vs. someone who has 3 or 4 coauthored pubs (either with a faculty member or with 4+ other people) in similarly ranked journals or even less good journals?  Fit? What are the elements used to assess fit? What is "fit" (besides clear mismatches of specialized fields)?

We all know coauthoring opportunities with faculty members are not equally available to all graduate students, this luck-based advantage clearly exists. I am genuinely curious about how search committees think about this advantage (especially when we are supposedly experts in social inequality)?

For me, I understand pubs with two co-authors who are both grad students/junior scholars being valued similarly to a solo authored pub. 

[Varies widely]

I have not seen anyone who values coauthored work over solo-authored work published in the same or better journals. For two papers that are similar in quality and placement, solo authorship definitely tells a search committee more about the candidate than a paper coauthored with a faculty member. But, quality and placement matter more than authorship.

For me, I value (a) quality, (b) placement, and (c) authorship of a paper, roughly in that order. For authorship, solo > 1st-authored > co-authored (2nd or higher), with a smaller distinction between solo & 1st than between 1st and co-authored. It is also my observation that solo-authored papers are less likely to be as good and less likely to be as well-placed. When they are, then they definitely mean more than a coauthored paper of similar quality/placement.

When I read CV's of new scholars I look for all kinds of signs of future productivity and impact. That includes well-written solo papers in minor outlets, well-placed major papers as a collaborating coauthor, engagement with ideas and methods likely to be fruitful down the road, and so on. Junior scholar CV's change rapidly. So, while we work with the information we have, I also realize how ephemeral these snapshots of accomplishment are for ABD's and AP's.

[ditto everything]

FWIW I read files in the same way as "Varies widely" and agree with everything they said. We're trying to judge future trajectories with every scrap of data we have. I've never heard of anyone (in sociology) valuing a coauthored paper more than an equivalent solo-authored one, but I've seen a lot of variation in how much colleagues do or don't discount coauthored papers (especially when they're a grad student's main pub).