Tommy and his friends learn about "fairness" from a bigger kid. He incorrectly explains fairness to be in his favor. The kid does not inherently know how to play by the rules and instead uses fear, intimidation, and manipulation to gain the advantage and have things go his way.
Chief Hopper teaches his kind not to underestimate small ants for they can unite into a mass group and defeat the grasshoppers. To Hopper, the core to control smaller species is to manipulate their mentality: continually frightening them, imprinting in their minds that they are powerless, keeping them away from the thought of uniting.