Merritt Ruhlen is a lecturer in Anthropological Sciences and Human Biology at Stanford, and a co-director of the Santa Fe Institute Program on the Evolution of Human Languages. He received his Ph.D. from Stanford in 1973.

Ruhlen is an extremely controversial figure in the linguistics community, from which he has been all but ostracized, due to his vocal support of the Proto World Hypothesis, which claims that all the extant languages of the world can be traced back to a single proto-language, and that this proto-language can be accurately reconstructed. Most mainstream historical linguists believe that Ruhlen's assumptions and methodology are unsound and unfounded, and think that there is simply no possible way to reconstruct a language that would had to have been spoken at least 30,000 years ago, and most probably many thousands of years before that.

The majority of criticisms of Ruhlen center around his use of mass comparison, which instead of using common historical linguistic methods of comparison, involves comparing the lexicons of however many languages one is investigating and examining them for words in two or more languages which appear similar phonologically and have a similar meaning. Historical linguists argue that most results turned up with mass comparison could easily be cases of simple coincidence. Furthermore, by using mass comparison, Ruhlen makes his data unfalsifiable. If he were to develope regular phonological correspondences between languages as in mainstream historical linguistics, than it would be possible to find examples which violated these correspondences, thus falsifying the hypothesis. This is impossible to do with Ruhlen's data, however, which makes linguists skeptical.

Ruhlen and his followers reply that the sheer volume of the correspondences which their mass comparisons have turned up is far too large to possibly be due to chance. They insist that even if many of the results were chance similarities, it is beyond belief that there could be so many similarities.

References

Trask, R. L., Historical Linguistics. London: Arnold, 1996.