In his latest blog post, Mike Huemer says:

That’s why traditionally, the vast majority of people (both lay people and philosophers alike) have accepted objective values, until pretty recently.

I don’t understand why he keeps saying things like this.

This is an empirical claim. Huemer presents no substantive empirical evidence in the form of historical, anthropological, or psychological data to support the claim that “the vast majority of people” have been moral realists. And he couldn’t do so even if he wanted to, because there isn’t much data to support this claim.

At present, we don’t even have good evidence most people in contemporary Western society are moral realists, and the same holds for what few studies have been conducted in cross-cultural contexts. The best studies, i.e., those that have corrected for at least some of the methodological shortcomings of earlier studies in the literature, find extremely high rates of antirealist responses from participants. See here:

Pölzler, T., & Wright, J. C. (2020). Anti-realist pluralism: A new approach to folk metaethics. Review of Philosophy and Psychology, 11(1), 53-82.

I’ve also linked a preprint that includes cross-cultural research. Here is the abstract:

Philosophers have long assumed that lay people believe morality to be objective. Recent psychological research casts doubt on this assumption. However, this research has so far mostly been limited to the United States. Are people from other cultures dominantly drawn towards non-objectivism as well? The present study investigates lay people’s abstract beliefs about moral objectivity in Brazil, Germany, Indonesia, Japan and the United States. On three distinct interpretations, our results suggest that people in these countries dominantly deny morality’s objectivity as well; that this denial takes somewhat different forms and appears to be somewhat more common in Indonesia and especially Japan, and somewhat less common in Brazil; and that lay people’s moral objectivity beliefs are weakly predicted by their age and level of political conservatism. These findings have important implications for the assessment of several philosophical arguments.

Note the bolded section:

our results suggest that people in these countries dominantly deny morality’s objectivity as well

There is a large empirical literature on the topic. Some early studies showed mixed evidence that was often reported as evidence for moral realism. As Polzler, myself, and others have noted, this was based on studies with significant methodological shortcomings and misleading interpretation of the data. See Polzler here:

Pölzler, T. (2018). How to measure moral realism. Review of Philosophy and Psychology, 9(3), 647-670.

And David Moss and my work here:

Bush, L. S., & Moss, D. (2020). Misunderstanding metaethics: Difficulties measuring folk objectivism and relativism. Diametros17(64): 6-21.

researchgate.net/public…