Anchor: Of all the household, he alone would be likely to recognize the symptoms of strychnine poisoning, and yet we find him the only member of the family to uphold strenuously the theory of death from natural causes. 
Entailed: He's the only one that would recognize the symptoms of strychnine poisoning.
Contradiction: In that situation, he would have no idea about strychnine poisoning.
Contradiction: The story talked post-apocalyptic life in America. 
Contradiction: Robert Brustein is a writer for the New Republic. 
Contradiction: the guys are fishing
Contradiction: Three people are talking and eating together