Ockham s razor

Quantum mechanics is part of the reductionist tradition in modem science, and the general claim, often just made implicitly as in any branch of reduction, is that the highest ideal one can aspire to is to derive everything from the theoretical principles. The less experimental data one needs to appeal to, the less one is introducing measured parameters the purer the calculation and the closer it approaches to the ideal of Ockham s razor of being as economical as possible (Hoffman, Minkin, Carpenter, 1996).2... 

Although actually in this article Hoffman et al. argue that using Ockham s razor may not always be the ideal approach to take in chemistry. 

Paradigms are also closely shaven by Ockham s razor. The principle that what is simplest is best may legitimize a paradigm, and monophyly is as simple as it gets. However, Ockham s razor may cut too finely when the simplest explanation is inadequate. As illustrated above, SET and LGT are not simple, but they are supported by evidence. Indeed, a monophylic explanation for the data supporting SET and LGT would have to be rejected by Ockham s razor as unnecessarily complicated . 

These models are nested the search starts with the simplest model and proceeds to the models of increasing degree of complexity (number of fitting parameters). An Ockham s razor principle is assumed here if more than one model is consistent with the data, the simplest model is preferred. For each model of motion, all parameters are determined from fitting, based on the simplex algorithm, to minimize the following target function ... 

The didactic principle of reiteration is a sort of converse to Ockham s Razor and might be called Ior s Ears Could 1 have that again in the other ear (Cf. [B, p. viii]). 

This possibility is illustrated in Fig. 25. The dip seems considerably too deep to be plausible. So while we cannot rule out this possibility, without firm evidence for the existence of such an intermediate, we will invoke Ockham s razor and return to the single-step model. 

That overall retention in similar systems is the norm later received firmer confirmation from studies of compounds where the stereochemistrry of both stannane and final product could be unambiguously assigned.37 152 This has been widely assumed to mean that each individual step (transmetallation and quench) is retentive, but the same result could arise from a double inversion. This possibility may not withstand the vigorous slicings of Ockham s razor,153 but it must be borne in mind as a conceivable mechanistic pathway in some instances. 

In the first volume of Advances in Quantum Chemistry [1] I published an article called Spin-Free Quantum Chemistry. Since then I have broadened this concept considerably and have changed the name of the subject to "freeon dynamics". The word "freeon1 means "free-of-spin" and not the common refrigerant. Freeon dynamics is a viable alternative (for light atoms and for molecules with light atoms) to the more-conventional fermion dynamics. The raison d etre for freeon dynamics is that it is conceptually and computationally simpler than fermion dynamics and so is consistent with Ockham s razor ... 

Hoffmann, Roald, Minkin, Vladimir L, 8c Carpenter, Barry K. 1996. "Ockham s Razor and Chemistry." Bulletin de la societe chimique de France 133 117-130. 

Gao, W. and Dalton, J.T. (2007) Ockham s razor and selective androgen receptor modulators (SARMs) are we overlooking the role of 5a-reductase Molecular Interventions, 7, 10-13. 

Occam s (or Ockham s) razor is a principle attributed to the 14th-century logician William of Occam which can be stated as follows ... 

To decide difficult cases one often uses as a stopgap the principle of Ockham s razor, i.e., one choses that interpretation of a mechanism that is the simplest. If the basis for this choice is clearly declared as a stopgap, it is acceptable — in spite of the danger that, later, other scientists will quote that interpretation without reservation. 

In recent years, there has been a re-appreciation of the work of Jeffreys on the application of Bayesian methods [121], especially due to the expository publications of E.T. Jaynes [118,120], In particular, the Bayesian approach to model class selection has been further developed by showing that the evidence for each model class provided by the data (that is, the probability of getting the data based on the whole model class) automatically enforces a quantitative expression of a principle of model parsimony or of Ockham s razor [98,164,242], There is no need to introduce any ad-hoc penalty term as was done in some of the earlier work on this problem. 

The principle of Ockham s Razor is attributed to William of Ockham (c. 1285—c. 1349), an English Franciscan friar. He is credited with the concept of Ockham s razor, which states that, simpler explanations are, other things being equal, generally better than more complex ones. ... 

Morris, A.M., Watzky, M.A., Agar, J.N., Finke, R.G. (2008) Fitting neurological protein aggregation kinetic data via a 2-step, minimal/ Ockham s razor model The Finke-Watzky mechtmism of nucleation followed by autocatalytic surface growth. Biochemistry, 47 (8), 2413-2427. 

The introduction and use of parsimony methods in phylogenetic estimation is described and discussed against the background of Ockham s razor and extremum principles in science generally. It is argued that the method of maximum likelihood applied to realistic models of evolutionary divergence is the optimum procedure, to which parsimony methods are often an acceptable approximation. 

Sober, E., Let s razor Ockham s razor, in Explanation and its Limits, Knowles, D., Ed., Cambridge University Press, Cambridge, 1990, pp. 73-93. 

Watkins, B. A., Li, Y., Lippman, H. E., Reinwald, S., Seifert, M. F. (2004). A test of Ockham s razor implications of conjugated linoleic acid in bone biology. American Journal of Clinical Nutrition, 79, 1175S-1185S. 

Ockham, William, 75 Ockham s razors 181,186 Ontology, scientific theory and, 66 Organism distribution, explanation for, 237 Orthology, 215... 

The most important task for a theoretician is the choice of a model. It may seem a paradox to emphasize that taking the largest model may not be recommended, even after a presentation of the codes with the implicit desire to be able to calculate the largest possible systems. The main contribution of a theoretician is to help analysis, which is by nature a simplification rather than to produce numbers. In this regard, a model does not have to be complete and sophisticated it should be constructed so as to explore the strict necessary causes of a phenomenon. Ockham s razor is a principle of parsimony that recommends selecting the fewest number of assumptions that provides the correct answer. Nevertheless, if one wants to reach the limit of the state of the art, the improvement of the model should prevail over that of the technique. Physics should not depend on the technique provided that mistakes are avoided. In the following, we want to outline some constraints in the choice of models for oxides. 

This formulation for the log evidence for model class Af, shows that it is the difference between two terms the first term is the posterior mean of the log-likelihood function, which is a measure of the average data fit for model class Mj, while the second term is the relative entropy between the prior and posterior distributions, which is a measure of the information gained about the parameters 0/ from the data V. Therefore, the log evidence is comprised of a data-fit term and a term which provides a penalty against more complex models that extract more information from the data. This gives an intuitive understanding of why the application of Bayes Theorem at the model class level automatically enforces Ockham s razor Pluralitas non est ponenda sine neccesitate ( entities should not be multiplied unnecessarily ). Although this information-theoretic interpretation was initially presented in Beck Yuen (2004),... 

Perhaps the aromaticity concept is unnecessary. Why attribute the stability of these species to aromaticity when simple delocalization of electrons may do as well That question is a good one, and needs an answer. It is not necessary to invoke special effects if simpler concepts will suffice. The principle of Ockham s razor says that when faced with a variety of equally attractive explanations, pick the simplest. 

Wielding Ockham s razor, we might say that the cyclopentadienyl anion is very stable because of the five resonance forms so apparent in Rgure 13.30. What then would we expect of the cycloheptatrienyl anion, whose seven resonance forms are shown in Figure 13.31 If an ion with five resonance forms is stable, surely one... 

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