What makes people irrational thinkers?

[emjay]

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"Resistant being" an operative word here. We are never free of cognitive bias, I don't think. But we aren't slaves to it either.

I agree with you that we are not essentially logical beings. I like Plato's allegory in Phaedrus where he likens us mentally to a chariot with three parts. Two horses and a charioteer. One unruly horse (desire), One obedient horse (emotion), and our rational inclinations (which are represented by the charioteer). Looking at that whole model, you can see that we as people are pretty much 95% emotion and desire-- when accounting for raw power... what really motivates us. Plato never thought that we should be more reasonable than we are desirous or emotional. In fact he considered it impossible. (One of the few matters Plato is decidedly correct on.) Rather, he thought the best role for our reasonable nature is to try it's best to keep the two horses on track as best it could. Only our more passionate nature can actually propel us forward through life. Our reasonable nature can do naught but try and steer as best it can.

Or, put another way by the Lebanese poet, Gibran:

 Your reason and your passion are the rudder and the sails of your seafaring soul.
    If either your sails or your rudder be broken, you can but toss and drift, or else be held at a standstill in mid-seas.
    For reason, ruling alone, is a force confining and passion, unattended, is a flame that burns to its own destruction.

https://poets.org/poem/reason-and-passion
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If I get nothing else out of life, I'd like to truly internalise that message; with the wisdom IMO coming from learning to accept it - both in self and others - rather than fight it. In other words I think we have this sort of illusion that every problem, or difference of opinion, can be addressed with logic alone but it just doesn't work that way, because no one is 100% logical in the first place, or in the sense of having that as the sole directing force in life, Vulcan or Data style (though I admit my analogy could be wrong on both counts - and you'd probably know that best - because I can't remember from Star Trek how much emotion does play a part in Vulcan thinking; whether it's suppressed or they just don't have it... and then with Data you've got him always talking with curiosity about human emotions, and whether or not he may be experiencing them, but in general it appears he acts from a position of logic alone).