The Third Law (Sebastien-2016)

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This is an answer to the question Mechanism of Method Employment that states "A method becomes employed only when it is deducible from some subset of other employed methods and accepted theories of the time."

The Third Law Sebastien 2016.png

This version of The Third Law was formulated by Zoe Sebastien in 2016.1 It is also known as the law of method employment. It is currently accepted by Scientonomy community as the best available answer to the question.

Broader History

The core idea of the third law can be traced back to Thomas Kuhn, Paul Feyerabend, Dudley Shapere, Larry Laudan, and Ernan McMullin, who suggested that our beliefs about the world shape how we engage with the world.

In his Science and Values, Larry Laudan has showed how the discovery of placebo effect and experimenter's bias led to changes in drug trial methods.2pp. 38-39 However, while Laudan’s account hints at aspects of the third law, it ultimately conflates methods and methodologies.3pp. 130-131

Another precursor of the third law is suggested by Ernan McMullin, who showed how the hypothetico-deductive method came to replace the Aristotelian Medieval method in the 18th century. According to McMullin, the employment of the hypothetico-deductivism was a result of accepting that the world is more complex than it appears in our observations.4pp. 32-34

The idea that our theories about the world shape our methods can also be traced back to Thomas Kuhn who argued for the synchronous change of theories and methods during paradigm shifts.5p. 109

While these accounts suggest that our accepted theories somehow impact our implicit requirements for investigating the world, they don't specify how exactly this shaping takes place. That is the gap that the third law attempts to fill.

Scientonomic History

The law replaced Barseghyan's original formulation of the Third Law. Sebastien's third law was the first to be accepted by Scientonomy community via the scientonomic mechanism of modifications.

Acceptance Record

Here is the complete acceptance record of this theory:
CommunityAccepted FromAcceptance IndicatorsStill AcceptedAccepted UntilRejection Indicators
Scientonomy21 January 2017The law became accepted as a result of the acceptance of the respective suggested modification.Yes

Suggestions To Accept

Here are all the modifications where the acceptance of this theory has been suggested:

Modification Community Date Suggested Summary Verdict Verdict Rationale Date Assessed
Sciento-2016-0001 Scientonomy 3 September 2016 Accept a new formulation of the third law to make it clear that employed methods do not have to be deducible from all accepted theories and employed methods but only from some. Accepted There was a community consensus that "the new formulation of the third law does bring an additional level of precision to our understanding of the mechanism of method change".c1 The community agreed that the new formulation "makes a clarification that, on its own, warrants this modification's acceptance".c2 Importantly, it was also agreed that the modification "solves the paradox of normative propositions".c3 21 January 2017

Suggestions To Reject

These are all the modifications where the rejection of this theory has been suggested:

Modification Community Date Suggested Summary Verdict Verdict Rationale Date Assessed
Sciento-2022-0002 Scientonomy 28 February 2022 Accept the new law of norm employment that fixes some of the issues of the current law of method employment and makes it applicable to norms of all types. Open

Question Answered

The Third Law (Sebastien-2016) is an attempt to answer the following question: How do methods become employed by an epistemic agent?

See Mechanism of Method Employment for more details.


Sebastien's third law explained by Gregory Rupik
The initial third law explained by Hakob Barseghyan

The initial formulation of the law, proposed by Barseghyan in The Laws of Scientific Change, stated that a method becomes employed only when it is deducible from other employed methods and accepted theories of the time.3p.132 In that formulation, it wasn't clear whether employed methods follow from all or only some of the accepted theories and employed methods of the time. This led to a logical paradox which this reformulation attempts to solve.1

This reformulation of the law makes explicit that an employed method need not necessarily follow from all other employed methods and accepted theories but only from some of them. This made it possible for an employed method to be logically inconsistent and yet compatible with openly accepted methodological dicta.

In all other respects, this formulation preserves the gist of Barseghyan's original formulation. According to the third law, a method becomes employed when:

  1. it strictly follows from some subset of other employed methods and accepted theories, or
  2. it implements some abstract requirements of other employed methods.

This restates Barseghyan's original suggestion that accepted theories shape the set of implicit criteria employed in theory assessment. When a new theory is accepted, this often leads to the employment of an abstract requirement to take that new theory into account when testing relevant contender theories. This abstract requirement is then specified by a new employed method.

The evolution of the drug trial methods is an example of the third law in action. For example, the discovery of the placebo effect in drug testing demonstrates that fake treatment can cause improvement in patient symptoms. As a result of its discovery the abstract requirement of “when assessing a drug’s efficacy, the possible placebo effect must be taken into account” was generated. This abstract requirement is, by definition, an accepted theory which stipulates that, if ignored, substantial doubt would be cast on any trial. As a result of this new theory, the Single-Blind Trial method was devised. The currently employed method in drug testing is the Double-Blind Trial, a method which specifies all of the abstract requirements of its predecessors. It is an apt illustration of how new methods are generated through the acceptance of new theories, as well as how new methods employ the abstract requirements of their predecessors.3pp. 132-152

In Barseghyan’s explication of the Aristotelian-Medieval method, he illustrates how Aristotelian natural philosophy impacted the method of the time. One of the key features of the Aristotelian-scholastic method was the requirement of intuition schooled by experience, i.e. that a proposition is acceptable if it grasps the nature of a thing though intuition schooled by experience. The requirement itself was a deductive consequence of several assumptions accepted at the time. One of the assumptions underlying this requirement was the idea that every natural thing has a nature, a substantial quality that makes a thing what it is (e.g. a human's nature is their capacity of reason). Another assumption underlying the requirement was the idea that nature of a thing can be grasped intuitively by those who are most experienced with the things of that type. The requirements of the intuitive truth followed from these assumptions. The scholastic-Aristotelians scholars wouldn’t require intuitive truths grasped by an experienced person if they didn’t believe that things have natures that could be grasped intuitively by experts.

The third law has also proven useful in explicating such requirements as Confirmed Novel Predictions (CNP). According to the hypothetico-deductive method, a theory which challenges our accepted ontology must provide CNP in order to become accepted. However, the history of CNP has been a point of confusion for some time. By the Third Law, one can show that the requirement of CNP has not always been expected of new theories. When Newton published his Principia, CNP were not a requirement of his professed method, yet they were still provided. On the other hand, Clark’s law of diminishing returns had no such predictions. This is because Newton’s proposal of unobservable entities, such as gravity and absolute space, challenged the accepted ontology of the time, while Clark’s simply accounted for the data already available. Thus, in utilizing the Third Law, one can discover both when certain criteria become an implicit rule and under what conditions they are necessary.


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Questions About This Theory

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  1. a b  Sebastien, Zoe. (2016) The Status of Normative Propositions in the Theory of Scientific Change. Scientonomy 1, 1-9. Retrieved from
  2. ^  Laudan, Larry. (1984) Science and Values. University of California Press.
  3. a b c  Barseghyan, Hakob. (2015) The Laws of Scientific Change. Springer.
  4. ^  McMullin, Ernan. (1988) The Shaping of Scientific Rationality: Construction and Constraint. In McMullin (Ed.) (1988), 1-47.
  5. ^  Kuhn, Thomas. (1962) The Structure of Scientific Revolutions. University of Chicago Press.