The Method of Levels of Abstraction

“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s11023-008-9113-7The use of “levels of abstraction” in philosophical analysis (levelism) has recently come under attack. In this paper, I argue that a refined version of epistemological levelism should be retained as a fundamental method, called the method of levels of abstraction. After a brief introduction, in section “Some Definitions and Preliminary Examples” the nature and applicability of the epistemological method of levels of abstraction is clarified. In section “A Classic Application of the Method of Abstraction”, the philosophical fruitfulness of the new method is shown by using Kant’s classic discussion of the “antinomies of pure reason” as an example. In section “The Philosophy of the Method of Abstraction”, the method is further specified and supported by distinguishing it from three other forms of “levelism”: (i) levels of organisation; (ii) levels of explanation and (iii) conceptual schemes. In that context, the problems of relativism and antirealism are also briefly addressed. The conclusion discusses some of the work that lies ahead, two potential limitations of the method and some results that have already been obtained by applying the method to some long-standing philosophical problems.Peer reviewe

A comparative study on the evolution of plastic zone between indentation and flattening contact

The peak of the ratio between the average pressure to yield strength is called hardness. The average contact pressure of elastic–plastic flattening and indentation contacts is studied by using numerical simulation. The similarity and difference between the two kinds of single asperity contacts are investigated. This paper chooses five kinds of elastic–plastic materials as the deformable-body. The yield strength of these materials covers the typical steel materials range used in the engineering project. And the effect of the evolution of the plastic zone under the contact surface on the contact pressure distribution is analyzed. Before the elastic zone under the contact surface disappears completely, the evolution of the plastic zone of the two types of contact is similar. However, the average pressure of indentation contact continues to increase after this, until it reaches the maximum. The average pressure of flattening contact reached the plateau since elastic core has disappeared, and after a while, it began to decrease

The Effect of Asperity Flattening During Cyclic Normal Loading of a Rough Spherical Contact

The effect of asperity flattening of a rough spherical contact during cyclic loading is investigated experimentally. Two types of surfaces are examined; the first is an “as-manufactured” isotropic surface and the second a smooth “laser-polished” surface. Both the surfaces exhibit a large amount of hysteresis of the load–displacement curve during the first load–unload cycles. This hysteresis is found to decrease as a function of the number of load cycles. A comparison of the experimental results with results obtained from a numerical model for a rough spherical contact shows good correlation. The model shows that for rough surfaces the total displacement is a function of the contacting asperities while for smooth surfaces the main contribution comes from the bulk displacement