The fourth chapter of World Hypotheses: A Study in Evidence (1942) is short in length, compared to other chapters.

"In scientific reasoning, a hypothesis is constructed before any applicable research has been done. A theory, on the other hand, is supported by evidence: it's a principle formed as an attempt to explain things that have already been substantiated by data", says the [Merriam-Webster Dictionary](https://www.merriam-webster.com/words-at-play/difference-between-hypothesis-and-theory-usage) > A _hypothesis_ is an assumption made before any research has been done. It is formed so that it can be tested to see if it might be true. A _theory_ is a principle formed to explain the things already shown in data. Because of the rigors of experiment and control, it is much more likely that a theory will be true than a hypothesis.

A _working hypothesis_ has a stronger meaning in history of philosophy dating back to 1850s in the pragmatic tradition, says the [Wikipedia entry on Working hypothesis](https://en.wikipedia.org/wiki/Working_hypothesis).

For Stephen C. Pepper, a _World Hypothesis_ would become a World Theory through a presentation of adequate evidence.

In the first section of Chapter IV: Hypotheses, Pepper contrasts an Interpretation of Hypotheses by Logical Positivists (of the [Vienna Circle](https://iep.utm.edu/viennacr/)) as _conventionalism_.

* Pepper then declares the focus of the rest of the book will be Structural Corroboration towards World Theories.

Through increasing the Scope and Precision of a system of structural hypotheses, a World Hypothesis coalesces.

The continuing pursuit of improved structural corroboration leads towards a World Hypothesis as an ideal. At some point, pragmatically, an Adequate World Hypothesis may be declared.