Answer
The Chauffeur
Work Step by Step
a. Lord Hazelton, the murdered man, was killed by a blow on the head with a brass candlestick.
b. Either Lady Hazelton or a maid, Sara, was in the dining room at the time of the murder.
c. If the cook was in the kitchen at the time of the murder, then the butler killed Lord Hazelton with a fatal dose of strychnine.
d. If Lady Hazelton was in the dining room at the time of the murder, then the chauffeur killed Lord Hazelton.
e. If the cook was not in the kitchen at the time of the murder, then Sara was not in the dining room when the murder was committed.
f. If Sara was in the dining room at the time the murder was committed, then the wine steward killed Lord Hazelton
Hypothesis: Let us assume that the cook was in the kitchen at the time of the murder. ....(h)
c ∧ h → The butler killed Lord Hazelton with strychnine [Modus Ponnens] ....(p)
p ∧ a → Lord Hazelton was killed by strychnine and a blow on the head ...(q)
We have a contradiction in p and q. Thus, our hypothesis must have been wrong
∴ The cook was not in the kitchen at the time of the
murder. (negation of supposition ....(g)
e ∧ g → Sara was not in the dining room when the murder was
committed. ......(i)
b ∧ i → Lady Hazelton was in the dining room when the murder was committed. .....(j)
d ∧ j → The chauffeur killed Lord Hazelton [Modus Ponens]
Hence, the chauffeur is the murderer.
