These are excerpts from Isaac Watts book about learning how to converse and debate. He's talking about our natural tendency to defend our position. 

 "It is exceedingly hard to dispute without gaining some invisible prejudice and good liking for the opinion we defend. So devoted are we to ourselves, that self love too easily engages our favor to the cause we have espoused, and for no other reason than because we espoused it. Though we may have had no kindness before for an opinion that we maintain for disputing sake, yet if a plausible and smiling argument for it occurs in our hasty thoughts, how prone are we to hug the creature of our brain, and be almost in love with the opinion for the sake of argument and we are insensibly captivated to esteem any thing that proceeds from ourselves. There is a certain wantonness of wit in youth, and a pleasing ambition of victory, which works in a young warm spirit, much stronger than a desire for truth. Upon the first sight of an objection against our arguments, our thoughts are strangely hurried away to ransack the brain for a reply, and we torture our invention to make our side have the last word."