Substance theory
Substance theory, or substance–attribute theory, is an ontological theory positing that objects are constituted each by a substance and properties borne by the substance but distinct from it. In this role, a substance can be referred to as a substratum or a thing-in-itself. Substances are particulars that are ontologically independent: they are able to exist all by themselves. Another defining feature often attributed to substances is their ability to undergo changes. Changes involve something existing before, during and after the change. They can be described in terms of a persisting substance gaining or losing properties. Attributes or properties, on the other hand, are entities that can be exemplified by substances. Properties characterize their bearers; they express what their bearer is like.
Substance is a key concept in ontology, the latter in turn part of metaphysics, which may be classified into monist, dualist, or pluralist varieties according to how many substances or individuals are said to populate, furnish, or exist in the world. According to monistic views, there is only one substance. Stoicism and Spinoza, for example, hold monistic views, that pneuma or God, respectively, is the one substance in the world. These modes of thinking are sometimes associated with the idea of immanence. Dualism sees the world as being composed of two fundamental substances. Pluralist philosophies include Plato's Theory of Forms and Aristotle's hylomorphic categories.
Ancient Greek philosophy
Aristotle
used the term "substance" in a secondary sense for genera and species understood as hylomorphic forms. Primarily, however, he used it with regard to his category of substance, the specimen or individual, qua individual, who survives accidental change and in whom the essential properties inhere that define those universals.In chapter 6 of book I the Physics Aristotle argues that any change must be analysed in reference to the property of an invariant subject: as it was before the change and thereafter. Thus, in his hylomorphic account of change, what is known as prime matter serves as a relative substratum of transformation, i.e. prime matter as a metaphysical principal in pure potency for the reception of a substantial form. In the Categories, properties are predicated only of substance, but in chapter 7 of book I of the Physics, Aristotle discusses substances coming to be and passing away in the "unqualified sense" wherein primary substances are generated from a material substratum by having gained the essential property that formally defines substances of that kind. Examples of such a substantial change include not only conception and dying, but also metabolism, e.g., the bread a man eats becomes the man. On the other hand, in accidental change, because the essential property remains unchanged, by identifying the substance with its formal essence, substance may thereby serve as the relative subject matter or property-bearer of change in a qualified sense. An example of this sort of accidental change is a change of color or size: a tomato becomes red, or a juvenile horse grows.
Aristotle thinks that in addition to primary substances, there are secondary substances, which are universals.
However, according to Aristotle's theology, a form of invariant form exists without matter, beyond the cosmos, powerless and oblivious, in the eternal substance of the unmoved mover.
Pyrrhonism
Early Pyrrhonism rejected the idea that substances exist. Pyrrho put this as:"Whoever wants to live well must consider these three questions: First, how are pragmata by nature? Secondly, what attitude should we adopt towards them? Thirdly, what will be the outcome for those who have this attitude?" Pyrrho's answer is that "As for pragmata they are all adiaphora, astathmēta, and anepikrita. Therefore, neither our sense-perceptions nor our doxai tell us the truth or lie; so we certainly should not rely on them. Rather, we should be adoxastoi, aklineis, and akradantoi, saying about every single one that it no more is than it is not or it both is and is not or it neither is nor is not.
Stoicism
The Stoics rejected the idea that incorporeal beings inhere in matter, as taught by Plato. They believed that all being is corporeal infused with a creative fire called pneuma. Thus they developed a scheme of categories different from Aristotle's based on the ideas of Anaxagoras and Timaeus. The fundamental basis of Stoicism in this context was a universally consistent ethical and moral code that should be maintained at all time, the physical belief of beings as matter is an important philosophical footnote, as it marked the start of thinking as beings as inherently linked to reality, instead of to some abstract heaven.Neoplatonism
argue that beneath the surface phenomena that present themselves to our senses are three higher spiritual principles or hypostases, each one more sublime than the preceding. For Plotinus, these are the soul or world-soul, being/intellect or divine mind, and "the one".Early modern philosophy
means by a substance an entity which exists in such a way that it needs no other entity in order to exist. Therefore, only God is a substance in this strict sense. However, he extends the term to created things, which need only the concurrence of God to exist. He maintained that two of these are mind and body, each being distinct from the other in their attributes and therefore in their essence, and neither needing the other in order to exist. This is Descartes' substance dualism.Baruch Spinoza denied Descartes' "real distinction" between mind and matter. Substance, according to Spinoza, is one and indivisible, but has multiple "attributes". He regards an attribute, though, as "what we conceive as constituting the essence of substance". The single essence of one substance can be conceived of as material and also, consistently, as mental. What is ordinarily called the natural world, together with all the individuals in it, is immanent in God: hence his famous phrase deus sive natura.
John Locke views substance through a corpuscularian lens where it exhibits two types of qualities which both stem from a source. He believes that humans are born tabula rasa or "blank slate" – without innate knowledge. In An Essay Concerning Human Understanding Locke writes that "first essence may be taken for the very being of anything, whereby it is, what it is." If humans are born without any knowledge, the way to receive knowledge is through perception of a certain object. But, according to Locke, an object exists in its primary qualities, no matter whether the human perceives it or not; it just exists. For example, an apple has qualities or properties that determine its existence apart from human perception of it, such as its mass or texture. The apple itself is also "pure substance in which is supposed to provide some sort of 'unknown support' to the observable qualities of things" that the human mind perceives. The foundational or support qualities are called primary essences which "in the case of physical substances, are the underlying physical causes of the object's observable qualities". But then what is an object except "the owner or support of other properties"? Locke rejects Aristotle's category of the forms, and develops mixed ideas about what substance or "first essence" means. Locke's solution to confusion about first essence is to argue that objects simply are what they are – made up of microscopic particles existing because they exist. According to Locke, the mind cannot completely grasp the idea of a substance as it "always falls beyond knowledge". There is a gap between what first essence truly means and the mind's perception of it that Locke believes the mind cannot bridge, objects in their primary qualities must exist apart from human perception.
The molecular combination of atoms in first essence then forms the solid base that humans can perceive and add qualities to describe - the only way humans can possibly begin to perceive an object. The way to perceive the qualities of an apple is from the combination of the primary qualities to form the secondary qualities. These qualities are then used to group the substances into different categories that "depend on the properties happen to be able to perceive". The taste of an apple or the feeling of its smoothness are not traits inherent to the fruit but are the power of the primary qualities to produce an idea about that object in the mind. The reason that humans can not sense the actual primary qualities is the mental distance from the object; thus, Locke argues, objects remain nominal for humans. Therefore, the argument then returns to how "a philosopher has no other idea of those substances than what is framed by a collection of those simple ideas which are found in them." The mind's conception of substances " complex rather than simple" and "has no clear and distinct idea of matter that can be revealed through intellectual abstraction away from sensory qualities".
The last quality of substance is the way the perceived qualities seem to begin to change – such as a candle melting; this quality is called the tertiary quality. Tertiary qualities "of a body are those powers in it that, by virtue of its primary qualities, give it the power to produce observable changes in the primary qualities of other bodies"; "the power of the sun to melt wax is a tertiary quality of the sun". They are "mere powers; qualities such as flexibility, ductility; and the power of sun to melt wax". This goes along with "passive power: the capacity a thing has for being changed by another thing". In any object, at the core are the primary qualities, the secondary quality, and tertiary qualities.
Robert Boyle's corpuscularian hypothesis states that "all material bodies are composites of ultimately small particles of matter" that "have the same material qualities as the larger composite bodies do". Using this basis, Locke defines his first group, primary qualities, as "the ones that a body doesn't lose, however much it alters." The materials retain their primary qualities even if they are broken down because of the unchanging nature of their atomic particles. If someone is curious about an object and they say it is solid and extended, these two descriptors are primary qualities. The second group consists of secondary qualities which are "really nothing but the powers to produce various sensations in us by their primary qualities." Locke argues that the impressions our senses perceive from the objects are not natural properties of the object itself, but things they induce in us by means of the "size, shape, texture, and motion of their imperceptible parts." The bodies send insensible particles to our senses which let us perceive the object through different faculties; what we perceive is based on the object's composition. With these qualities, people can achieve the object through bringing "co-existing powers and sensible qualities to a common ground for explanation". Locke supposes that one wants to know what "binds these qualities" into an object, and argues that a "substratum" or "substance" has this effect, defining "substance" as follows:
This substratum is a construct of the mind in an attempt to bind all the qualities seen together; it is only "a supposition of
an unknown support of qualities that are able to cause simple
ideas in us." Without making a substratum, people would be at a loss as to how different qualities relate. Locke does, however, mention that this substratum is an unknown, relating it to the story of the world on the turtle's back and how the believers eventually had to concede that the turtle just rested on "something he knew not what". This is how the mind perceives all things and from which it can make ideas about them; it is entirely relative, but it does provide a "regularity and consistency to our ideas". Substance, overall, has two sets of qualities — those that define it, and those related to how we perceive it. These qualities rush to our minds, which must organize them. As a result, our mind creates a substratum for these objects, into which it groups related qualities.