It is said in many discussion groups, blogs, and sites on the Internet that Joseph hid his practice of polygamy because he feared violent repercussions from the community if they found out. I've always felt this argument was extremely weak because Joseph was already persecuted (beaten, tarred and feathered, thrown in jail) for what he believed and taught. Exposing to the public a belief and practice of polygamy wouldn't have made the persecutions any worse.
The other night I happened to read again Chapter 7 of Joseph Smith Fought Polygamy. At the end of the chapter, the authors address this issue in an excellent manner. So I thought I would quote what they said.
The belief that Joseph taught and practiced polygamy, but did it secretly because he feared opposition, is a ridiculous, weak belief according to Joseph's sons, Joseph III, Alexander, and David.
Joseph Smith III was eleven and a half years old at the time of his father's death. The young lad had a deep respect for, and a close relationship with, his father. He was intelligent and studious, and knew more about the polygamy conspiracy against his father than most Saints, because he often witnessed his mother and father's joint work to counteract the false polygamous charges which Bennett had made. He had the opportunity to observe his father's behavior, language, and mindset in public and private, both in the Prophet's office and home. As an example, the father required that Joseph III sometimes accompany him upon the rostrum during worship services; and the boy stayed at least once with his father while the Prophet was in hiding. Joseph III had this to say in answer to Brigham Young and others' claims that his father kept a polygamous revelation and polygamous marriages secret because of fear of the public:
To assert that Joseph Smith was afraid to promulgate that doctrine [polygamy], if the command to do so had come from God, is to charge him with a moral cowardice to which his whole life gives the lie. Nor does it charge him alone with cowardice, but brands his compeers with the same undeserved approbrium. The very fact that men are now found who dare to present and defend it, is proof positive that Joseph and Hyrum Smith would have dared to do the same thing had they been commanded so to do.
The danger to the lives of those men would have been no more imminent, nor any greater in the preaching of "Celestial Marriage," than it was in preaching the "Golden Bible" and the doctrine that Joseph Smith was a prophet blessed with divine revelation. For the preaching of these tenets many lost their lives; Joseph and Hyrum Smith were repeatedly mobbed, were imprisoned and finally died, in the faith originally promulgated, but—if we may judge from their public records,—not believers in polygamy. (Joseph Smith III, Reply to Orson Pratt [tract], 4)
Alexander Hale Smith, a son of the Prophet, was six years old when his father was slain. After studying the polygamous charges against his father he wrote:
We also learn another fact: ... That in the brain of J. C. Bennett was conceived the idea, and in his practice was the principle first introduced into the church; and from this hellish egg was hatched the present degrading, debasing, and destructive polygamic system, known as "spiritual wifery," or the "celestial marriage," so called.
It is said that Joseph Smith, the martyr, received a revelation revealing the "celestial marriage" and instituting "plurality of wives." I have already examined the testimony of Joseph Smith, concerning the marriage ceremony; and he declares that he knew of no other system of marriage than the one quoted from the Book of Doctrine and Covenants [1835 Kirtland Edition, 101; 1844 Nauvoo Edition, 109; 1866 Liverpool Edition, 109; RLDS DC, 111]. . . .
But says one, "that was only a sham to blind the eyes of our enemies." Shame on the man, or set of men, who will thus wilfully charge the two best men of the nineteenth century, the two Prophets of the most high God, with publishing to the church and the public at large a lie, and signing their names to it.
"Oh! but it was done to save their lives." A very likely story, when those two men had faced death and the world for fourteen long years, preaching the word of God to a sin-cursed generation. No, no, it will not do, you must meet the truth with better weapons than that, if you expect to make much of a battle. Besides all that, Is it not written, that "He who seeketh to save his life shall lose it, and he who loseth his life for my sake shall find it," and did not they know this. Yes, a thousand times yes; it was their hope, their consolation in times of danger. (Alexander H. Smith, Polygamy: Was It an Original Tenet of the Church of Jesus Christ of Latter Day Saints? [tract], 6)
In spite of all that Joseph did to proclaim that he was not lying when he said he had not had a polygamous revelation, and that he was honest in his condemning of polygamy, members of the LDS Church proclaim even to this day that Joseph did receive Section 132 and was a polygamist. Joseph's side of the story has been, and is being, purposefully ignored by the LDS Church. They never give Joseph credit for having spoken the truth on this subject. In fact, they consider it was necessary and acceptable for the Prophet to lie, even though the Scriptures teach that lying is a major sin. It is ridiculous to believe that Joseph lied about polygamy because he feared a prejudiced public—for even the Mormons publish that Joseph bravely faced death at Carthage, saying, "I am calm as a summer's morning" (Times and Seasons 5 [July 15, 1844]: 585; RLDS DC 113:4b; LDS DC 135:4). When Joseph's statements against polygamy are taken at face value and are read with the realization that he was not a cowardly liar—an astounding fact becomes obvious—that it was Brigham and his pro-polygamist party that palmed a fraudulent polygamy conspiracy upon the Saints, which has blighted the Latter Day Saint Movement for over a century and a half.
So well said, there is nothing more to comment about this issue.