Regarding the term ‘Concrete’ as opposed to ‘Abstract’. Does ‘concrete’ mean a sensible (detectable by the senses) thing, ie a corporeal sensible thing, or only a ‘particular’ thing. I can think of a nonmaterial particular thing such as the Angel Gabriel. Would this be an instance of a ‘Concrete’ thing.
Answer by Craig Skinner
One standard classification of what exists is as follows:
Entities (Existents) comprise Universals and Particulars.
* properties (e.g. redness)
* relations ( e.g. bigger than)
* concrete particulars, in turn divided into Things (objects, physical items) and Events (e.g collisions, or my feeling bored, which we can regard as a mental Event or as a mental Thing if you wish).
* abstract particulars (eg numbers, propositions).
Universals have instances in Particulars. So, for example, the Universal property ‘redness’ has an instance in a particular post box.
Equivalently, Particulars are instances of Universals. For example, Birmingham’s relation to Gretna Green is as an instance of the Universal relation ‘bigger than’. 17 is an instance of the Universal property ‘primeness’.
So, some concrete particulars are indeed, as you say, ‘corporeal sensible things’ (Things), chairs for instance, others are not, being particular events (Andy Murray winning Olympic gold, say).
The Angel Gabriel, if he (it?) existed, would be a particular, not abstract, therefore concrete. Presumably not physical. Hence a series of concrete Mental Particulars, or if you think mental activity has to inhere in some immaterial substance, a concrete immaterial Thing. Not detectable by the senses, unless miraculously able to assume sensible form and appear to you. Gods, demons and devils would all be in this category. I must say I think it is an empty category (other than in imagination and fiction).
Not everybody agrees with the above classification.
Some deny Universals, holding that the redness of a particular post box is not an instance of anything, rather just a particular redness (a ‘trope’ or ‘mode’ of that box, not transferable without the box).
Others augment the Universals category to include Kinds (Substantial Universals, as opposed to Properties and Relations which are Non-substantial Universals). Thus ‘human being’ would be a Substantial Kind and you and I, being instances, are Substantial Particulars. A Substance, roughly, is something that can bear properties or relational instances eg a post box, me, an electron, Gabriel (he would be an immaterial substance of course).
Yet others deny Abstract Particulars, holding that numbers, say, are fictional entities (existing only in the story of mathematics, as Sherlock Holmes exists only in the stories of Conan Doyle), or even nonexistent entities that nevertheless have properties (like being prime).
I hope this has clarified rather than confused. I must admit that Ontological Categories is not the best choice of topic when you try to explain why philosophy matters to somebody who thinks it’s all probably a waste of time. This kind of metaphysics was big in Aristotle’s and in mediaeval philosophy, lost ground in modern times, but is looking up again in the 21st Century (E J Lowe’s ‘The Four Category Ontology’ is a good example).
Answer by Helier Robinson
Your question involves two classifications: concrete and abstract, and particular and universal. The concrete is often defined as ‘known through the senses’ but a better definition is simply ‘any sensation’, such as a colour, sound, taste, smell, or a tactile sensation such as hot or cold, hard or soft, heavy or light, rough or smooth, or penetrable or impenetrable. This is a better definition because we also know relations through the senses (for example: ‘This tree is taller than that one’) and relations are abstract: that is, they have no concrete qualities. Particulars are names or descriptions that apply to individuals; thus Socrates and Plato’s philosophy teacher are respectively a name and a description of one person.
Universals are names or descriptions that apply plurally; that is, to more than one individual. The problem of universals is the problem of what their meaning is. Traditionally there are three answers: nominalism, conceptualism, and realism (or Platonism).
Nominalism is the view that words for universals are their own meanings; this is best illustrated by the phrase that all thought is silent speech. We cannot think without language. This view is advocated by those, like Bishop Berkeley, who cannot discover abstract ideas in their own minds. It has several defects: it cannot explain synonyms, and it cannot explain how one abstract proposition can be stated in two different languages.
For those who can discover abstract ideas introspectively, these difficulties vanish. A concept is a combination of a word and an abstract idea and a proposition is a series of concepts that convey a structure of abstract ideas in language. Any language can convey any one proposition. This is conceptualism.
Platonism is the more elaborate view that all abstract ideas have a reference, so that, for example, the abstract idea conveyed by the word ‘two’ and the numeral 2, is the number two. This has difficulties also, because how can you distinguish the number two and instances of it? In the expression 2+2=2×2=2*2 there are six instances of two, but which is the number two itself?
One further distinction is between thought and imagination: thought deals with abstract ideas and imagination deals with concrete images of sensations: usually pictures, but also sounds for some people such as composers or tastes for chefs. So, to answer your question, the concrete is sensational and may be either particular or universal, and is perceived or imagined; and the abstract is non-concrete and is discovered introspectively by some people or is thought. And the Angel Gabriel is concrete and imagined, or possibly perceived.