Guest: How air conditioning changed politics and world

Thank God Willis Haviland Carrier invented air conditioning — for the most part.

Before air conditioning, the heat drove us outside and brought us together. Friends sought the shade of trees or a refreshing dip in a lake or river.

On the hottest nights, whole families brought their blankets and pillows to riverbanks, where it was cool.

In the evening, neighbors sat on their large front porches, en...