Can we as a human take a perfect objective decision? I think it is nearly impossible ( at least for me). I bow to the people who can do so.
Think of it carefully... Isn't it true; most times answer is ready with us; it just comes out of our mind and afterwards, we try to defend it by giving some nice logic or theory. This is especially evident when the decision is somehow relating to the people we already know. If somebody we don't like make a very valid point,most times we would find an excuse why that something won't work and go ahead. Though this is just an obvious example, most of our life is full of such kind of non-obvious decisions.
I don't know, how to analyze further on this isssue. It is just nearly impossible. I have just put it from my own experience and my observations of people around me.
One of the great persons in formalizing thinking and inventor of 'lateral thinking' Mr. Edward DeBono has included emotions a red hat in his methodology 'six hats thinking' for the exact same reason.
There is something called "emotional intelligence" which is supposed to help us in life, but I don't know. I confess I have never really read about it but I just be another nice theory. For me, I always think that being conscious about something is more important than reading theory. You read theory and forget it but if you are conscious about something it remains at the back of your mind and after some time becomes part of your emotions.