In this context, "fool" is an action not an immutable nature - it's the action of talking about topics that are either well below the intellectual level of the

In this context, "fool" is an action not an immutable nature - it's the action of talking about topics that are either well below the intellectual level of the ongoing discussion, or a distraction from it. It doesn't matter why a person does this, it matters that they do it at all. Up to a certain rate of inflow of well meaning fools, the group can absorb and socialize them. If there is a fire-hose of them, you get an Eternal September and the forum dies.