sligs are humans at heart...you probably have a friend that is crazy about always getting the lastest processor PC or the lastest cellphone,palm, console, etc. that is too worried about having more than everyone else to actually get a life.
that is what sligs represent, they mind is too busy thinking that their buddy got a new armor upgrade, or a new uzi and they didnt, to even think about why the magog gives them weapons, or how they could get weapons whitout them, or even consider the thought that the world is unfair.Besides, the gluks dont even allow them to sleep, they have to do it undercovers to get away with it...if you are underslept you cant ever think right, I imagine they'd be too busy trying to get sleep to do any philosfical thinking, and the few moments they are fully awake, they are spending all their energy thinking about the next upgrade.
how much weapons they have is all they are, if they dont have the biggest weapon, they feel they are a failure, and get depressed, so as all the sligs always know someone who's got more than them, every slig is always too busy thinking about how to get the next upgrade, and still sleep to think about anything else. I think the most long-term thinking they will ever do is if their fav team will win the championship

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that's for magog-owned guard sligs anyway, I dont really know how the newscaster or valet's employment works.
and yeah, pretty much every race in woddworld is majorily stupid, but that's OW's message, every race represnts one of our aspects, and OWI's showing us all how stupid the world is, by using humor and characters we dont take seriously, it's the oldest thing in the world, Jesters were the only ones allowed to tell the truth in the court.
And their representation isnt even all that exagerated, you could find an example of all of the cruelties going on in oddworld in some part of human history. it is particularily amazing for me how similar we are to vykkers...I think vykkers even fall short at representing the cruelties human scientists get away with.
besides, gluks and vykkers are nobodies anyway, even maggie has to report to the chroniclers, the chronichlers are the highest in the chain of command of OW as far as we know, sligs could never manage a factory well enough to put up with the chronichler's demands.