* This builds A Theory of Knowledge Based on Doubt, rather than on certainties.
In 1981, Franklin M. Berry wrote "[An Introduction to Stephen C. Pepper’s Philosophical System via World Hypotheses: A Study in Evidence](https://doi.org/10.3758/BF03333873)", saying > _World Hypotheses_ can be conceived of as consisting of three interrelated contributions: > * (1) a theory of knowledge based on the progressive refinement of doubtful commonsense knowledge; > * (2) "root metaphor theory," that is, a theory of the origin of world hypotheses in commonsense metaphor; and > * (3) an analytical examination of the six world hypotheses that have served as the respective fundamental assumptions for competing schools of philosophy throughout recorded history.
In 1980, [Elmer Duncan](https://www.whbfamily.com/obituaries/obituary-listings?obId=899750) described the value of _World Hypotheses_. > Pepper's _World Hypotheses_ gives the philosopher a useful way of classifying various metaphysical positions. Does it really help to say that, in some sense or other, Plato, Bishop Berkeley and Hegel were all Idealists? Pepper's classification scheme is more illuminating, and, fur ther, it helps us understand these various metaphysical positions by explaining their origins in their different root metaphors. > * Source: Duncan, Elmer H. 1980. “The Philosophy of Stephen C. Pepper: An Appraisal.” _Paunch_ 53: 63. [preserved on the Internet Archive](https://web.archive.org/web/20070523221046/http://people.sunyit.edu/~harrell/Pepper/pep_duncan.htm)
In 1982, [Andrew J. Reck](https://en.wikipedia.org/wiki/Andrew_J._Reck) writing on "[Pepper and Recent Metaphilosophy](https://www.jstor.org/stable/43852928)" described _World Hypothesis_ as a "classic contribution to metaphilosophy". * In the 1930s and 1940s, Pepper developed _World Hypotheses_ as a Metaphilosophy of Metaphysics.
In 2020, [Michael C. Jackson, OBE](https://www.researchgate.net/profile/Michael-Jackson-37) wrote of the Theoretical Contribution of World Hypotheses to Critical Systems Thinking
In 1972, Pepper wrote about the potential to develop Systems Philosophy as a World Hypothesis, in a review of [Ervin Laszlo](https://thelaszloinstitute.com/about/ervin-laszlo/)'s book [Introduction to Systems Philosophy (1972)](https://doi.org/10.4324/9781003205586).
In 2022, [Zhichang Zhu](https://scholar.google.com/citations?user=pXpqv38AAAAJ&hl=en) analyzed Methodological Pluralism and Root Metaphors to suggest a paradigm root metaphor as a trap, and an evolutionist root metaphor as more pluralist and responsive.
In 2015, [Scott R. Stroud](https://commstudies.utexas.edu/faculty/scott-stroud) proposed World Hypotheses as Evidentiary, Engaged, and Inclusive Pluralism in a metaphysics of criticism applicable to aethetics