Often in apologetic literature, such as was argued in the topics essay on polygamy, I will see arguments that negative moral judgements of Joseph’s introduction and practice of polygamy should be discarded as they are the fallacy of presentism.
Presentism is defined by the “anachronistic introduction of present-day ideas and perspectives into depictions or interpretations of the past”.
With regard to polygamy, apologists frequently argue that 1) older men marrying young girls was culturally acceptable at the time, but that when a polygamist did it, it came with stigma and constitutes unfair persecution, and 2) that polygamy and its variations have been acceptable at various times in various cultures. They use these two points to argue that Joseph’s polygamy should not be judged in a moral light.
I think this argument would work for many issues, such as whether it is morally or spiritually wrong for Joseph to use folk magic to channel divine revelation, but I think it is fallacious to apply it to polygamy, specifically. This is for two reasons.
- Arguing “presentism” contradicts Mormon theology – In Mormonism God is eternal and God’s law (i.e. Celestial law) is eternal and unchanging. This poses two insurmountable problems for apologists. First, it means that presentism is nullified because if it was moral then, it should also be moral now. Yet, no apologist is going to argue that it is appropriate today for old men to marry child brides because they themselves view this as immoral. Yet, this is the very thing that apologists are trying to avoid by arguing “presentism”, since the court of public opinion is very unfavorable toward 38 year old and older men forcibly persuading young girls into marital relationships. Second, the fact that the moral standard taught by Mormonism has shifted so radically over time either points toward a church-wide apostasy or that the whole thing was never connected to the divine in the first place. In other words, Mormon theology presents a moral absolute that is subject to additional morals being added in the future, but apologists are arguing in favor of moral relativism while still accepting the moral absolutes of the theology.
- Arguing “presentism” ignores contemporary views on polygamy – When apologists argue that Joseph’s practice of polygamy should be given lighter moral judgement, they ignore that the moral outrage toward marrying women with living husbands and marrying young girls was viewed as morally wrong then, just as it is now. If it were not morally wrong, Joseph would have never made the practice secret, the participants in the practice would not have viewed themselves as a “sacrifice” for their families or for their salvation, Joseph would not have lied about practicing polygamy when accused, Joseph would not have been murdered after his polygamy was revealed by the Nauvoo Expositor, the Republican party would not have declared polygamy and slavery as the “twin relics of barbarism”, the British government would not have started a public information campaign warning potential female Mormon converts that they would be pressed into polygamy upon reaching Salt Lake, Hollywood would not have created the film “Trapped by the Mormons”, and so on. Further, arguing that marrying young girls was normal in that time period, census data simply does not support that conclusion. The age gap between Joseph and the young girls he married is easily among the largest of the marriages in the U.S. that entire decade. When 17-20 year old girls married, it was in nearly every case to a young boy near her age, and almost no women younger than 17 married at all since most had not even entered menarche until then. There was a clear moral stigma against child brides that apologists ignore when arguing that harsh judgements against Joseph Smith’s polygamy should be dismissed as “presentism”.
It is valid to point out that we should avoid applying modern moral judgements to past actions, however, in the case of Joseph Smith and his practice of polygamy, Mormon theology does claim to provide an absolute moral framework that can be used to judge Joseph’s actions and contemporary attitudes toward the most problematic aspects of his polygamy make the same moral condemnation as contemporary attitudes today. Arguing that we should “give Joseph a break” by dismissing moral judgements of Joseph’s polygamy as presentism is a fundamentally unscholarly position to take.
 Census data from the 1800’s and 1900’s show that the average age of marriage for women was typically from 22 to 23, with a few notable dips immediately after the Civil War and WWII, when the average age for women dipped to 20-21. It also shows that in the 1800’s, the number of teenage girls who were married was very low in all regions of the United States except in the Mountain West (especially Utah) and the Southwest where one quarter or one third of teenaged women were married.
 While it is true that women in their late teens and early 20’s historically tend to be in relationships where there is an age gap, this age gap between the male and female is on average between 5.5 and 4.5 years in the 1800’s and 2.2 years through most of the 1900’s. Further, girls below the age of 17 are almost never in relationships where there is an age gap, and it has been that way for nearly three centuries. Further still, this trend is roughly stable across all Western European and American cultures, such as in Sweden and the U.S., the average marriage age gap in 1850 was 5.5 years. This phenomenon is known as the Hajnal Line, which is a boundary defined by marriage age gaps and the age of the earliest ages. The western side of this line, which would culturally include the United States, is characterized by marriages where both partners are relatively close in age. While the record quality from the 1800’s is poor relative to today, we see the same trends in higher contrast from modern data, which can give us a sense of the expected distribution for the 1800’s as well. All that to say, an age gap of 20+ years is extremely unusual today and would have been then as well, and more so between a teenaged girl and a man in his late 30’s.
 The only counter point I’ve been able to find so far is that age homogamy was on the rise in Europe in the late 1800’s, and presumably in the U.S. as well. This seems to indicate that a transactional marriage culture (i.e. marriage for political, economic, or other non-romantic reasons) tends to result in larger age gaps between spouses. Doctrinally, early Mormon polygamy is decidedly transactional, as the role of polygamy is to increase the spiritual power and authority of a man and gain access to exaltation. Over time, this has transitioned to include monogamy as well, but a strong distinction is still made between “temple marriages” and civil marriages, always with the meaning that the transaction of accessing exaltation through marriage can only be found in the temple. With regards to presentism, it is wrong for apologists to downplay the moral condemnation of large age gaps between polygamist spouses on the grounds of presentism since nearly every neighbor of the early Mormons also strongly condemned the practice, and often explicitly because of the age gaps. However, it is valid for apologists to make a theological argument instead; to claim that in the Restoration, marriage is transactional for spiritual exaltation and inherently not motivated by romance, and therefore large age gaps are not only of no consequence, but also an inevitable result of transactional marriages. I doubt, however, that most apologists would want to take such a position given that the vast majority of members, and perhaps apologists themselves, now view marriage as romantic, not transactional.