He also took an unpopular stance against the death penalty for persons with mental illness, going so far as to campaign for leniency for Charles J. Guiteau, the assassin of President James Garfield on the basis that the man was not guilty because of insanity.

While still in medical school during the American Civil War, he served as an assistant surgeon in the West Gulf squadron of the United States Navy aboard the gunboat New London.

After the war, and upon his graduation from medical school, he married Elizabeth Ann Alden of Westville, Connecticut on December 25, 1866.

Lest I may be accused of inconsistency, I may say that whatever I have done during the past few years in the way of detecting and exposing mediums, clairvoyants and mind-readers has been, not for the purpose of ascertaining the truth or falsity of the claims made by these performers and their advocates, since that question is … settled definitely, and forever by deduct- ive reasoning, but partly in order to solve some questions relating to the psychology of jugglery – a most instructive and much neglected – and partly, also, out of regard to the weaker brethren who are unable to employ deductive reasoning, and can only be taught through what, in some way, appeals to the senses.

Beard became involved with Thomas Edison's claim to be able to project electrical influence without current through etheric force.