Consider this situation, which we face often:
We fear disagreements, disagreements to our views, opinions, thoughts and point of views. We fear that someone in that meeting will just stand up and blurt out some crap against my absolutely correct opinion. We feel good in our comfort zone and want to shoot down the criticism.
Well, disagreement is good and healthy, though not always. It makes your mind work. It makes you consider a plethora of other aspects which you might not have considered at the first place. Healthy criticism contributes towards polishing your opinions, deliverables, improve communication skills, spurt creativity and innovation and brings the best out of a team.