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1. Music musical tone colour; timbre
2. Logic the characteristic of a proposition that is dependent on whether it is affirmative or negative



a philosophical category, expressing an object’s essential determinateness, which is inseparable from its being and thanks to which it is precisely that object and no other.

Quality reflects the stable interrelationship among the constituent elements of an object. This interrelationship specifies the object and makes it possible to distinguish it from all others. It is precisely because of quality that each object exists and can be thought of as something delimited and set apart from other objects. On the other hand, quality also expresses the general factor that characterizes the entire class of objects that are of the same kind. ‘Two different things always have certain qualities … in common” (F. Engels; see K. Marx and F. Engels, Soch., 2nd ed., vol. 20, p. 547). Any object constantly changes; nevertheless, it possesses a certain stability that is also expressed as a qualitative determinateness.

The category of quality was first thoroughly analyzed by Aristotle, who defined it as the “differentia of the essence” (Metaphysics, V 14 1020b35; Russian translation, Moscow, 1975). Aristotle noted the flux of qualities as states of things, their capacity for being transformed into their opposites. Medieval Scholasticism interpreted the so-called “hidden qualities” as eternal and unchanging “forms.” The distinction between primary and secondary qualities, based on a mechanistic world view, took shape in modern philosophy.

Hegel defined quality as a logical category constituting the initial stage in the cognition of things and in the emergence of the world, as well as the immediate character of an object’s being. “Quality is in fact a definiteness that is identical with being and is immediate to it. Something is what it is thanks to its quality, and, losing its quality, it ceases to be what it is” (Soch., vol. 1, Moscow-Leningrad, 1929, p. 157).

Dialectical materialism proceeds, first of all, from the acknowledgment of the objectivity and universality of the qualitative determinateness of things. The quality of an object is revealed in the aggregate of its properties. However, an object does not consist of properties and is not a certain “cluster of properties,” but rather it possesses them: “Qualities do not exist but only things with qualities, and indeed with infinitely many qualities” (F. Engels; see K. Marx and F. Engels, Soch., 2nd ed., vol. 20, p. 547). What is regarded as a property is the mode of manifestation of a given aspect of an object’s quality in relation to other objects with which it enters into interaction. A property of an object thus consists in its producing in another object this or that effect and in manifesting itself in its own unique mode in this action. Depending on the real and cognitive context, an object radiates, so to speak, its various aspects, its qualities. For example, a person exhibits his different qualitative facets to a physician, lawyer, writer, sociologist, anatomist, psychologist, and so forth.

The higher the level of the organization of matter, the greater is the number of qualities that it possesses. Inasmuch as each object is in infinite connections with other things, it therefore possesses an infinite number of properties. Hence all attempts to define quality as the complete aggregate of properties lead to infinity. The category of an object’s quality cannot be reduced to some of its properties either. It expresses the integrated characteristic of the functional unity of an object’s essential properties, of its internal and external determinateness, of its relative stability, and of its difference from other objects or its resemblance to them. Quality not only manifests itself but can change and be formed in these relations. Just as matter cannot be reduced to an aggregate of its properties, so also no object can be dissolved into its own properties: it is their bearer.

The qualitative determinateness of an object depends primarily on its structure, the nature of the relations among the elements of the whole, and on the composition of its elements. A change in quality is caused by a restructuring of the relations among the elements, by an alteration of the elements themselves, or by a transformation of both. The world consists not of finished and unchanging things but represents rather an aggregate of processes within which things are constantly coming into being, developing, and being annihilated, as well as being transformed into other things having other qualities. Inasmuch as an object, thanks to its quality, appears as this very object rather than something else, so a change in quality signifies the transformation of a given object into another one. Furthermore, qualitative changes in a thing occur each time at a different level: they may be connected with a change of that which is specific precisely for a given, unique object or for all objects of a given class. In any qualitative change there is a certain more general and, at the same time, more profound level of the object’s quality that remains essentially the same: it is only a variation of its existence that changes. Thus, a qualitative change may be also connected both with the transformation of a given phenomenon into another one and with a change in the state and form of existence of essentially the same object.

The category of quality expresses a given stage in man’s cognition of objective reality. In the initial stage of cognition an object of study appears before the subject primarily as a particular property or series of properties. In immediate sense perception quality appears as a certain multiplicity of properties. “First of all, impressions flash by, then Something emerges, —afterward the concepts of quality (the determination of the thing or the phenomenon) and quantity are developed.… The very first and most familiar to us is sensation, and in it there is inevitably also quality” (V. I. Lenin, Poln. sobr. soch., 5th ed., vol. 29, p. 301). Cognition proceeds from quality to quantity and thence to their unity—measure. Any object represents a unity of quality and quantity.


Marx, K. Kapital, vol. 1. In K. Marx and F. Engels, Soch., 2nd ed., vol. 23.
Engels, F. Anti-Dühring. Ibid., vol. 20.
Engels, F. Dialektika prirody. Ibid.
Lenin, V. I. Filosofskie tetradi. Poln. sobr. soch., 5th ed., vol. 29.
Hegel, G. W. F. Sock, vol. 5. Moscow, 1937.
Kedrov, B. M. O kolichestvennykh izmeneniakh v prirode. [Moscow]1946.



The totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs. Not to be mistaken for "degree of excellence" or "fitness for use" which meet only part of the definition.



The perceived value in something. It implies excellence in a product. The IEEE defines quality as the degree to which something meets the customer's needs or expectations. See QA and software quality assurance.
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Many thanks to this team of researchers, among others (all notably at universities, not from pet food companies) who have been publishing scientific evidence regarding the protein quality, amino acid content, digestibility, and safety of various dog food ingredients and products.
Pixley KV, Bjarnason MS (1993) Combining ability for yield and protein quality among modified-endosperm opaque-2 tropical maize inbreds.
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The flour extraction rate is lower, the lower protein levels, with increasing degree of extraction of the protein quality of flour or other baking quality decreases [20].