s. For example, to talk about colour and to talk about shape, to talk about sensible appearance and to talk about physical‑chemical constitution, to talk about internal structure and to talk about interaction and interrelation with other things, and so on, all exemplify different modes of abstraction.
The sense in which the much‑abused word "category" is used in the context of a logical investigation of categories is the sense in which category of proposition corresponds to mode of abstraction. In general, different categories of proposition result from different modes of abstraction. To take a very simple example. "This is red" and "This became red in the process of being painted" are propositions of different category—the first exemplifying what one might (in semi‑Hegelian language) term a category of "being" or "quality", and the second of "becoming" or "causality". Their connection by way of abstraction is evident, since the first proposition is relatively more abstract than the second, and could be called an abstraction from the second. In both information is assembled, and the assembly of information in the second is such as to render a more concrete account of the same thing of which the first gives a more abstract account.
To investigate differences of category, therefore, is not simply to describe the ways words are permitted to be put together in various languages, as Ryle and other linguistic philosophers have supposed. It is to investigate modes of abstraction and their assembly, which are expressed in the permissibility and impermissibility of combinations of words.
In his paper on Categories Ryle said that "category propositions" describe and distinguish "the logical type" of different expressions used in statements, and so concern "only collocations of symbols". But he added that this does not equate them with "the propositions of philologists, grammarians or lexicographers . . . Nor does it imply that they can say nothing about the 'nature of things'. If a child's perplexity why the Equator can be crossed but not seen, or why the Cheshire Cat could not leave its grin behind it is perplexity about the 'nature of things', then certain category‑propositions will give the required information about the nature of things. And the same will hold good of less frivolous type‑perplexities."
Because he confined philosophy to describing "collocations of symbols", Ryle may be justly likened to Horatio. At the same time, because he set philosophy the task of formulating category‑propositions, and considered that this (especially in its "less frivolous" applications) would throw some light on the "nature of things", it may be said of him that there is more in his philosophy than he dreamed of. For the yield of this investigation is nothing more nor less than the principles of materialist dialectics.
Dialectics, as an investigation and discipline distinct from formal logic, deals with categoriesand so studies and distinguishes modes of abstraction and assembly of abstractions. Evidently, for the purposes of managing information there is required not only the observance of formal consistency, as enjoined by formal logic, but also the observance of the rules of abstraction and assembly of abstractions, as enjoined by dialectics. Dialectics comprises the procedures for arriving at less abstract and more generalised working conceptions of ourselves and our environment by the proper conduct and assembly of the different modes of abstraction.
Thus, for example, it is generally agreed among Marxists that dialectics has to do with understanding things in their inter‑relations and changes, as opposed to the "metaphysical" way of considering things separately, out of relationship and in abstraction from their changes. Evidently, to get a concrete picture of any phenomenon we must assemble the available information in a way that adequately reflects the actual interconnections and motion of things, and thus understand the separate properties of things, and their temporary states, as products of processes of interaction and change. T