The symptoms of age-related cognitive decline include being unable to remember whether you’re in Vermont or New Hampshire, and what the talking points of your own presidential campaign are, but recalling exactly what you said nearly 60 years ago when you had a summer job as a lifeguard at a pool in Wilmington, Del. and a ‘bad dude’ called Corn Pop took umbrage when you ordered him to put on a shower cap so he looked like an old lady and then, to further emasculate him in front of his ‘boys’, called him ‘Esther’. The symptoms of gross partisanship and...