Method Rejection theorem (Barseghyan-2015)

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This is an answer to the question Mechanism of Method Rejection that states "A method ceases to be employed only when other methods that are incompatible with the method become employed."


Method Rejection theorem was formulated by Hakob Barseghyan in 2015.1 It is currently accepted by Scientonomy community as the best available answer to the question.

Scientonomic History

Initially, the method rejection theorem was accepted as deducible from the conjunction of the first law for methods and Harder's zeroth law. Barseghyan noted that this initial deduction was "similar to that of the theory rejection theorem. And just as its sibling theory rejection theorem, this theorem is also somewhat trivial".1pp. 174


We can use the short, hypothetical example from Barseghyan (2015) to illustrate the initial deduction of the method rejection theorem.

Say we have a set of accepted theories and a very simplistic method, which consists of only one requirement that can be roughly explicated as:

In order to become accepted, a new theory must explain all known facts with more precision and accuracy than they are explained by accepted theories. Suppose also that, as a result of changes in the accepted theories, some new method becomes employed. Question: what happens to this old method? Does it get rejected or does it still remain employed together with the new one?

The answer to this question depends on whether the two methods can be employed simultaneously. By The Zeroth Law (Harder-2015), if the requirements of the two methods are compatible with each other, then the old method remains employed together with the new one or, conversely, if the requirements of the two methods are incompatible, then the zeroth law dictates that the old method should go. ... If our new method has no conflict between its new requirement and the old one – the two are complementary. Therefore, the two requirements will become simultaneously employed. But what if the new method were incompatible with the old method? ... This new requirement voids the old requirement. Thus, the new method is in conflict with the old method. In this case, by the law of compatibility, the old method will have to go.1pp. 172-3

After the replacement of Harder's zeroth law with the compatibility corollary, suggested by Fraser and Sarwar, it became accepted that the method rejection theorem is a deductive consequence of the first law for theories and the compatibility corollary.2pp. 72-74

Acceptance Record

Here is the complete acceptance record of this theory:
CommunityAccepted FromAcceptance IndicatorsStill AcceptedAccepted UntilRejection Indicators
Scientonomy1 January 2016The theorem became de facto accepted by the community at that time together with the whole theory of scientific change.Yes

Question Answered

Method Rejection theorem (Barseghyan-2015) is an attempt to theory the following question: When does an employed method become rejected?

See Mechanism of Method Rejection for more details.


According to the method rejection theorem, a method ceases to be employed only when other methods that are incompatible with it become employed.


Reason: Method Rejection Theorem Deduction

By the first law for methods, an employed method will remain employed until it is replaced by other methods. By the compatibility corollary, the elements of the scientific mosaic are compatible with each other at any moment of time. Thus, a method can only become rejected when it is replaced by an incompatible method or methods.1pp. 172-176 2pp. 72-74

Method Rejection Theorem deduction (Barseghyan-Fraser-Sarwar-2018).png

Method Rejection Theorem deduction (Barseghyan-Fraser-Sarwar-2018).png

This reason for Method Rejection theorem (Barseghyan-2015) was formulated by Patrick Fraser and Ameer Sarwar in 2018.2

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  1. a b c d  Barseghyan, Hakob. (2015) The Laws of Scientific Change. Springer.
  2. a b c  Fraser, Patrick and Sarwar, Ameer. (2018) A Compatibility Law and the Classification of Theory Change. Scientonomy 2, 67-82. Retrieved from