In science, when we arbitrarily do something, we are trying to be as unbiased as possible.  It is very important to not pick sides or take a position on something based on emotion, personal tastes, or anything else that could sway our judgment.  The scientist must make careful observations, collect data from the experiment, analyze the data, then match up the results to the hypothesis that was put forth earlier in the experimental process.  Often times, it is due to the arbitrary nature of the scientific method that scientists make the discoveries they encounter, because they disengaged their "feelings and emotions".