Authorities believed Druitt was the Ripper

The argument

One of the top investigators in the Ripper case, Assistant Chief Constable Sir Melville Macnaghten, named Druitt as a suspect in a private memorandum on February 23, 1894. Following Macnaghten's retirement in 1913, he claimed to know the exact identity of Jack the Ripper based on private information obtained from the Ripper's family. He was referring to Montague John Druitt. Comments by Henry Richard Farquharson, MP for West Dorset, and others including journalists and public officials from the Ripper's era indicated that the Ripper was the son of a surgeon and had committed suicide at the end of 1888. Druitt was the son of local Dorset surgeon and he committed suicide in December of 1888.

Premises

Counter-arguments

Official suspicion is not proof, and Macnaghten's case is weak on its own terms. He wrote his memorandum years after the murders, named Druitt only as one of three possible suspects, and conceded the information was private and unprovable — while getting basic facts about Druitt wrong, including his profession. The contemporary rumour of a surgeon's son who killed himself was hearsay circulating after the fact, not evidence tying Druitt to any crime scene. That a retired official believed something decades later, without producing the family information he claimed, cannot establish identity.

Rejecting the premises

[Rejecting P1] Macnaghten named Druitt only as one of several suspects, wrote long after the events, admitted the evidence was private and unprovable, and made factual errors about him. [Rejecting P2] A general rumour of a surgeon's son who committed suicide is hearsay that fits many people and ties Druitt to no actual evidence.