Early into World Hypotheses: A Study in Evidence (1942) Chapter IV: Hypotheses, Stephen C. Pepper declares the focus of the rest of the book will, in effect, be focused on the _danda_ defined in Types of Corroboration.
The first three chapters of the book acknowledges logical positivism, as a leading philosophy of that period, alongside American pragmatism that emphasizes common sense. Pepper repositions these branches of philosophy as world hypotheses that work differently.
> ... we hereby reserve the right to retract anything we say in these preliminary pages, so far as anything here is found to be dogmatic or biased. The purpose of these pages is simply to lead us intelli- gently into an understanding of world theories, not to prescribe to them. [p. 73] >The only legitimate cognitive sources of prescription, I believe, are world theories, and the only legitimate critics of such prescriptions, other world theories. > * Common sense, as we have seen, cannot prescribe anything. It can vitalize, it can guarantee us against utter skepticism, but irresponsibility is one of its intrinsic traits. > * Nor can data in the guise of positivism legitimately prescribe anything beyond the undoubted cognitive value of their own mode of cognitive refinement. > When positivism undertakes to prescribe for knowledge in general, it becomes, as we saw, either dogmatic or metaphysical and unpositivistic. > Only world theories through structural corroboration acquire a cognitive right to prescribe concerning knowledge -- a prescription which is of course not dogmatic, but a particular sort of refinement. We, therefore, standing now outside of world theories, cannot and would not attempt to prescribe to them. Yet, like men betting at a race track, we may perhaps make some shrewd observations about the horses that are to run, their condition, their build, their training, their jockeys, and the state of the turf, though what we say or think will mean nothing to the contestants and will have no effect upon the course of the race. [pp. 73-74 editorial paragraphing added]
Having completed the long preamble, Pepper declares the focus on structural hypotheses.
> From now on, but for one brief comment, we shall be discussing only structural hypotheses. Common-sense hunches obviously need refinement, as all dubitanda do. Conventionalistic hypotheses growing out of the positivistic treatment of data make no cognitive claims. Our interest, therefore, will henceforth be focused upon structural hypotheses -- of which world hypotheses are examples, -- for these do make cognitive claims. They purport to inform us about the structure of the world. [p. 74]
Pepper might or might not be following systems definitions of structure as _arrangement in space_ and process as _arrangement in time_. There are philosophical details on [_Substance_ in the Stanford Encyclopedia of Philosophy](https://plato.stanford.edu/entries/substance/) > Forms are Plato’s substances, for everything derives its existence from Forms. In this sense of ‘substance’ any realist philosophical system acknowledges the existence of substances. Probably the only theories which do not would be those forms of logical positivism or pragmatism that treat ontology as a matter of convention. According to such theories, there are no real facts about what is ontologically basic, and so nothing is objectively substance.