THIS TIME of the year is when people make resolutions they may struggle to keep. One reason for that is confusion. According to Gallup, a pollster, three in five adults drink alcohol. About 45% think drinking even in moderation is bad for their health, while 43% think it has no effect. Americans drink more spirits (or hard liquor) now than during the Civil War—a time period so filled with drunkenness that some historians say it sparked the temperance movement.  This is despite something that has long been known by public-health researchers.