In his essay, “On Cannibals”, Michel De Montaigne wrote “…we seem to have no other criterion of truth and reason than the type and kind of opinions and customs current in the land where we live. There we always see the perfect religion, the perfect political system, the perfect and most accomplished way of doing everything.” [pp109-109] Is Montaigne right, wrong, or a combination of both?

In his essay “On Cannibals”, Michel de Montaigne was reacting in part to the great age of European exploration, which introduced Europeans to many exotic ideas and cultures. It was a period of great intellectual ferment, in which ideas about religion and morality were being challenged by scientific developments, exploration, and internal reforms (such as the rise of Protestantism).
In this particular passage, the use of the term "we" is somewhat misleading. Montaigne begins his essay with a discussion of how Greeks reacted to observing the Roman military organization. Montaigne, like all educated Europeans of his period, was intimately familiar with Greek and Latin literature. Many Arabic works were also available in Latin translation, as a result of contacts with the Moors in Spain. Byzantine refugees had brought many eastern Greek works to Italy after the fall of Constantinople. The biblical Old Testament, a foundational work of European culture, was written in Hebrew, and the entire Bible is set in the Middle East. Many of the ideas from these cultures were widely known by the French of Montaigne's period and were greatly influential.
On one level, therefore, Montaigne's statement is inaccurate. The inaccuracy, though, has to do with his using sweeping generalization to over-dramatize his point. The argument that he is trying to make could be phrased more cautiously, in saying that many of us often treat as universal the ideas and values of our own particular places and times. That somewhat more modest statement, with the qualifications of "many" and "often," rather than the sweeping unqualified "we" and "no other," is an observation of the phenomenon known as ethnocentrism.
The reason why it is important for students to study diverse cultures and ideas is precisely to avoid this tendency to believe that the viewpoints of one particular culture contain universal truths. Instead, as one studies other cultures, one can think critically about one's own value systems and beliefs. In his praise of the "savages" and their closeness to nature, Montaigne is urging his readers to do this. It is still true that, for example, Americans of European descent can still benefit from learning about the beliefs of many Native American tribes. Thus, Montaigne is partially right in his statement.
https://brians.wsu.edu/2016/11/04/michel-de-montaigne-on-cannibals-1580/