Microsoft Word - 29.4 Boulos Review of Zenker REV Paging.doc


©
Pierre
Boulos.
Informal
Logic,
Vol.
29,
No.
4
(2009),
pp.
480‐
482.


Book Review 
 
Frank Zenker. 2009. Ceteris Paribus in Conservative 
Belief Revision: On the Role of Minimal Change in 
Rational Theory Development. [Series:  Europäische 
Hochschulschriften Reihe 20: Philosophie  Vol. 731] 
Frankfurt: Peter Lang Publishers. (Pp. 145; ISBN-13: 
978-3631572832;  €34.00 US$49.95) 
 
 
The aim of Ceteris Paribus in Conservative Belief Revision 
(CPCBR) is to  “contrast or minimally mutilating revisions of 
empirical theories” as this is understood in Alchourrón, Gärdenfors 
and Makinson’s theory (AGM) of belief revision.  A published 
revision of Zenker’s PhD dissertation, the book looks at a narrow 
aspect of theory development embodied in the relatively recent 
literature looking at rational changes in beliefs in response to new 
information.  AGM aims at expounding the minimal properties 
such a belief revision process ought to have.     The author claims 
the book can be followed or understood without presupposing 
background understanding in formal logic.  It should be noted, 
though, that such a background is helpful as Zenker’s text is chalk 
full of highly technical language.  This reviewer was thankful for 
having some exposure to formal and axiomatic systems.  The book 
should be of interest to philosophers and historians of science alike, 
not to mention informal logicians, argumentation theorists, and 
epistemologists to be sure.  Some background familiarity with 
philosophy of science concepts would be an asset in reading this 
book. 
 The book is divided into six chapters, any of which reads well 
as a stand-alone section.  The first chapter, “Entrenchment and 
Scientific Change,” introduces nicely the concept of epistemic 
entrenchment and its role in scientific reasoning and change.  
Simply, how does one handle a discovered inconsistency within a 
belief-state K, a logically closed set of propositions?  Zenker points 
out the ramifications of adopting a Duhem-Quine approach to this 
situation that moves away from conjunctive connections among the 
members of K to an ordering relation on K such that some elements 
of K are more entrenched than other elements of K.  In other 
words, entrenchment contributes to theoretical importance.  In 
order to develop this sense of entrenchment, Zenker introduces, 
axiomatically, epistemic entrenchment and then shows how a 
particular ordering relation specifies epistemic entrenchment, 
especially in light of historical examples. 






























































Review
of
Ceteris
Paribus
481


  
 Chapter 2, “Epistemic Entrenchment vs. The Specialization 
Relation”, explores two different approaches to modelling 
differentially entrenched elements of a theory or logically closed 
and consistent set of propositions. In order to assess the expressive 
power of AGM’s ability to capture the least entrenched, and most 
vulnerable, proposition in K, Zenker’s rigorous analysis and 
comparison to structuralism indicates that AGM is no better than 
structuralism, both in regard to theory-nets and to theory-strings.  
The historical background in this chapter is Newtonian Particle 
Theory.  
 Turning to the lively historical example of attempts at 
reconciling Newtonian mechanics with Mercury’s anomalous orbit, 
Chapter 3, “The Mercury Anomaly and Minimal Revision”, 
examines conservative revision.  Conservative revisions are 
exemplified by the “hypothetical completion of antecedent 
conditions by so far unobserved gravitational masses.”  Like the 
Lunar Problem that plagued Newton (the moon perturbs in her 
orbit twice as much as Newton thought his theory could account), 
the perihelion advance of Mercury’s orbit was met, until Einstein’s 
Theory of General Relativity, with various gravitational solutions.  
These included alternative gravitational theories (gravitation 
equations include not only inverse square but maybe even lower 
order terms like inverse power of four, etc.), other planets within 
the orbit of Mercury, and reductions of gravitation to electro-
dynamics.  Interestingly, in the historical accounts Newtonian 
mechanics is not thrown outright, but is said to be minimally 
revised.  To what extent are these revisions minimal?  Zenker is 
correct in pointing out that structuralist reconstruction fails in 
prioritizing the formal elements over the historical. 
 Building on the case study from the previous chapter, Chapter 
4, “Ceteris Paribus as Completeness Assumptions”, looks at 
whether the conservative revision of completing initial conditions 
with suitable hypotheses can be understood as contractions of a 
ceteris paribus clause.  As such, these clauses would function as 
completeness clauses in which conservative revision hypotheses 
could be found. 
 The fifth chapter, “Ceteris Paribus Everywhere”, extends 
Zenker’s analysis of ceteris paribus laws.  On his account, these 
laws are to be understood as formulations on the way to better 
theories.  As a completeness assumption, it turns out that ceteris 
paribus plays an important role in testing a theory and explaining 
apparent exceptions (like the perihelion of Mercury).  The chapter, 
if nothing else, provides a nice assessment of the important  
 
 






Pierre
Boulos
482


discussions on theory choice and construction in the 
philosophy of science. 
 Finally, in “The Myth and Reality of Minimal Change”,  
Zenker looks at two shorter case studies exhibiting conservative 
revisions to theoretical generalizations.  The sixth and final chapter 
examines a revision to early thermodynamics as well as the idea of 
neutrinos in radioactive decay.  On Zenker’s account we move 
from incommensurability to the understanding that empirical 
theories develop.  In the face of inconsistencies in K, it would 
appear that something has to be done, whether radically or 
conservatively.  Zenker has illustrated instances where theoretical 
developments can be understood as minimal revisions.  These 
illustrations, nonetheless, do not provide a strong case that minimal 
revisions ought to be the norm. 
 This is a book worth examining.  Its highly technical 
perspective may make it inaccessible to some, however it does sit 
nicely at the intersection of philosophy of science and 
argumentation theory.  The argumentation theorist unfamiliar the 
more technical aspects of the philosophy of science could actually 
begin the book in Chapters 3 and 4, and then move to the 
beginning.  Finally, the reader should be prepared to perform a bit 
of formal “calisthenics” in reading Zenker’s book.  Although a 
background in formal logic and model theory are not needed, 
having some familiarity with formal logic and model theory 
certainly helps. 
 
 
PIERRE BOULOS 
 
Centre for Research in Reasoning, Argumentation & Rhetoric 
University of Windsor 
Windsor, ON 
Canada  N9B 3P4 
boulos@uwindsor.ca