Descartes intends for ‘attribute’ the fundamental characteristics of the infinite substances. The only ones that we can actually get to know are: thinking and extension (res cogitans and res extensa). Material things derive from the attribute of extension and all non material things by the attribute of thought, or rather - as Spinoza says - things and ideas are respectively the ways of being of the attribute: extension and the ways of being of the attribute: thought.
In the text of the philosopher Vladimir Solov’ëv 'The Crisis of Western Philosophy' as a deepening of the thought of Descartes we have his admission of a real plurality of things or individual substances that have in ‘thought’ and in ‘extension’ their essential attributes; Descartes recognizes the authentic existence of a plurality of bodies and a plurality of spirits. But from what does this plurality come from? What is the difference of the various substances between them?
As for Descartes, all the content of an extended substance condenses in the extension, an extended substance can be distinguished from another only because of particular forms or modes. In fact, a material object stands out and is separated from another by a) its position in space, b) its size, c) its configuration, and d) for the coordination of its parts. Now, all this is nothing more than a series of particular ways of extension and has absolutely nothing to do with the substance itself as such.
The same must be said about the relationships that are established between two thinking substances, because the thought and its particular forms are to the thinking substance as the extension and its particular forms are to the extended substance. But, in this way, if all that determines the difference and the separation is condensed in the attributes and in their ways and has nothing to do with the substances themselves, and if the substances themselves, as substances, do not differ at all from each other but are absolutely identical, it is evident that several substances do not exist, and there is, instead, only one that has as its attributes and at the same title, both thought and extension.
But to what are reduced in this case the things and the single individual beings? In their uniqueness they can not be substances because the substance is only one; they may not even be its attributes because the attribute, by definition, is the common content of all things of the same nature. It only remains to consider individual things as particular ways of the attributes: a single material object will be a way of extension, a thinking individual, a spirit, will be a way of thought.
The Encyclopedia Sapere.it shows that in its broadest logical- grammarian meaning, attribute is each determination of a subject that is affirmed or denied. In this sense the term attribute coincides with the term ‘predicate’, the significance of which is now used almost exclusively. Strictly, attribute is opposed to accident and to the way, as a quality inherent and constitutive of substance.
In this sense the term is used by Descartes who intends for attributes the permanent qualities of the substance, finite. Is then used by Spinoza for whom - since there are no finite substances - the attributes are of God alone, the only infinite substance, and, infinite in the number, they shall express the eternal essence. However, of these infinite attributes of substance we can know only two: thought and extension. The term is involved in the discussions of English empiricism, which, through the analyses of Locke, Berkeley and Hume, leads to the denial of the reality of substance.
The English empiricism, first with John Locke and then more decisively with David Hume, reacts to the conception of the subject as substance, criticizing both his notion (Locke), then the same "subject" (Hume). But thus empiricism comes to skepticism, to the inability to place the correlation between subject and predicate on solid foundations having an impact on the possibility of scientific knowledge. Like Descartes, although starting from an opposite perspective, the empiricists come to a dualism, to a split between the subjective dimension of experience, and the objective one of external reality. This gap between reality and its subjective representations coming from experience will be radicalized by Kant as an opposition between phenomenon and ‘thing’ in itself.
In contrast to the old one, now it is the subject to prevail on the external object, until becoming a metaphysical independent entity (Descartes), generating as a reaction the denial of the substance (empiricism).