What?! What, you say?
Actually, it is what Brigham Young and Joseph Smith had to say, and they also laid claim to all truth, where it could be found. They felt that their grasp of truth was under construction.
An analysis starts with this (from LDS.org) where it states:
“Mormonism,” so-called, embraces every principle pertaining to life and salvation, for time and eternity. No matter who has it. If the infidel has got truth it belongs to “Mormonism.” The truth and sound doctrine possessed by the sectarian world, and they have a great deal, all belong to this Church. As for their morality, many of them are, morally, just as good as we are. All that is good, lovely, and praiseworthy belongs to this Church and Kingdom. “Mormonism” includes all truth. There is no truth but what belongs to the Gospel. It is life, eternal life; it is bliss; it is the fulness of all things in the gods and in the eternities of the gods (DBY, 3).
Brigham Young not only stated that many in the sectarian world were “,just as good as we are” but they had truth. As a result, he said:
“It is our duty and calling, as ministers of the same salvation and Gospel, to gather every item of truth and reject every error. Whether a truth be found with professed infidels, or with the Universalists, or the Church of Rome, or the Methodists, the Church of England, the Presbyterians, the Baptists, the Quakers, the Shakers, or any other of the various and numerous different sects and parties, all of whom have more or less truth, it is the business of the Elders of this Church (Jesus, their Elder Brother, being at their head) to gather up all the truths in the world pertaining to life and salvation, to the Gospel we preach, … to the sciences, and to philosophy, wherever it may be found in every nation, kindred, tongue, and people and bring it to Zion (DBY, 248).”
So in his time he felt that he did not have all religious (or all other) truth and that we needed to study the truths others had, gather them up, and bring them to Zion to be understood, digested and shared.
Going on to other quotes from Brigham Young:
“Be willing to receive the truth, let it come from whom it may; no difference, not a particle. Just as soon receive the Gospel from Joseph Smith as from Peter, who lived in the days of Jesus. Receive it from one man as soon as another. If God has called an individual and sent him to preach the Gospel that is enough for me to know; it is no matter who it is, all I want is to know the truth.” (DBY, 11)
And as for conflicts with science (and reprising about the gospel and evolution):
““…our religion will not clash with or contradict the facts of science in any particular. You may take geology, for instance, and it is a true science; not that I would say for a moment that all the conclusions and deductions of its professors are true, but its leading principles are; they are facts-they are eternal; and to assert that the Lord made this earth out of nothing is preposterous and impossible. God never made something out of nothing; it is not in the economy or law by which the worlds were, are, or will exist. There is an eternity before us, and it is full of matter; and if we but understand enough of the Lord and his ways, we would say that he took of this matter and organized this earth from it. How long it has been organized it is not for me to say, and I do not care anything about it. As for the Bible account of the creation we may say that the Lord gave it to Moses, or rather Moses obtained the history and traditions of the fathers, and from these picked out what he considered necessary, and that account has been handed down from age to age, and we have got it, no matter whether it is correct or not, and whether the Lord found the earth empty and void, whether he made it out of nothing or out of the rude elements; or whether he made it in six days or in as many millions of years, is and will remain a matter of speculation in the minds of men unless he give revelation on the subject. If we understood the process of creation there would be no mystery about it, it would be all reasonable and plain, for there is no mystery except to the ignorant.” (Brigham Young, Journal of Discourses, vol. 14, pg. 116, 14 May 1871)”
Of course Brigham Young got his position from Joseph Smith:
“One of the grand fundamental principles of Mormonism is to receive truth, let it come from whence it may.” (Discourses of the Prophet Joseph Smith, p. 199)
Now Joseph Smith did embrace an approach to inspiration similar to many twelve step programs (and, I know, he said it first).
“A person may profit by noticing the first intimation of the spirit of revelation; for instance, when you feel pure intelligence flowing into you, it may give you sudden strokes of ideas, so that by noticing it, you may find it fulfilled the same day or soon; [that is,] those things that were presented unto your minds by the Spirit of God, will come to pass; and thus by learning the Spirit of God and understanding it, you may grow into the principle of revelation, until you become perfect in Christ Jesus.” (B.H. Roberts, History of the Church 3:381)
And Joseph Smith also said (from Joseph Smith and “The Only True and Living Church”):
“‘Wherein do you differ from others in your religious views?’ In reality and essence, we do not differ so far in our religious views, but that we could all drink into one principle of love. One of the grand fundamental principles of ‘Mormonism’ is to receive truth, let it come from whence it may.” “Have the Presbyterians any truth?” he asked on another occasion. “Yes. Have the Baptists, Methodists, etc., any truth? Yes. . . . We should gather all the good and true principles in the world and treasure them up, or we shall not come out true ‘Mormons.’“
They both also talked about the prophets of other lands and peoples and that God spoke to them as well as to us.
But the bottom line was that we need to gather all the good and true principles and treasure them, share them and grow from them or we do not come out true members of the Church.