Sometimes, you read or hear something, to which you have an instant reaction. You can provide a reason, there and then, why you agree with something, or alternatively why the speaker is a mistaken moron.
More often, however, the mind is slow to form a response. The statement grates, but you cannot put into words why that may be so. You fester for days, and those idle moments, in the queue or on the bus, are devoured as you excavate the depths of your thoughts for what you are sure is an obvious answer.
Sometimes you unearth the quip that you seek, but too late. I heard a French phrase for this: L’esprit d’escalier, The Spirt of The Staircase. It is that witty one-liner that you never said during the argument, which you only remember as you are walking down the stairs to leave the dinner party (are all Parisian dining rooms on the first floor, I wonder?)
With online argument, these issues can be a killer. The ease of publishing your thoughts on a blog means that, for maximum readership, those responses have to be published quicker than the mainstream! A politician writes or says something in the morning. By lunchtime, detailed responses are already available online. That evening, there are already 250 contributions in the comments. Only a day later, it feels like old news. Letting your argument stew for a day, or a week, is to truly miss the party. You do find the answer you were looking for, but everyone else has descended to the street and gone somewhere else. You are left alone, arguing with yourself.