Aristotelian substance=Things that ‘are’ in a primary way:

Aristotle’s central concept is that of a reality or substance. Primary, central realities are spatio-temporal items in the world in which we live, which we perceive through our senses, and with which we are in active contact – in both ways. Things like human beings, their limbs and organs, other animals, plants, their parts like leaves or branches, but also artefacts like houses, beds, mountains and valleys, lumps of coal, gold nuggets, single beans, a straw. . . Today, we are more convinced of the primacy of things we do not perceive through our sense: atoms and their particles, energy and electric waves. We ground our ‘reality’ on assumptions and explanations that are beyond our senses.

They are, what they are, by possessing essential qualities. Something is a bed because it is something in which you can sleep. Due to being a living being of the animal kind, and endowed with reason a being is a human being. When these essential qualities disappear, the being so conceived goes out of existence. Before they appear the being is not yet in existence. These primary items, substances, come as particular beings. They are also ordered into species and genera, in a hierarchy of criteria, that throw a large net of inclusions and exclusions. They are the bearers of qualities, location, quantitative determination etc.

Realities or substances combine matter and form. At least some, indeed many of them, have purposes. All of them are able to be involved in processes of change by contributing to the change of other items, and by changing as a consequence of the action of other items on them. (Passive and active causation of the ‘bringing about’ kind, commonly called ‘efficient causation.’)

To be matter of a substance is to be in the function of matter relative to something that is form. To be the form of something is to be the form realized in some matter. To be is to unite matter and form. The brick in the wall of the house is matter, relative to the form of the house. Taken in isolation, the house is the unity and a unit of form and matter. The house is the form of a thing only because it is made real by its matter. The house appears, as it were, through the material and its organization, i.e. its ‘matter.’

But the house can simultaneously be ‘matter’ in a different respect, for example: It is matter to the form ‘city.’ Matter and form are relative notions. They call out for each other. You need to hold on to the form of something when you try to determine its matter. You need to hold on to something that counts as matter when you try to determine what the form is of some item.

Change: Great variety of changes: genesis or coming-into-being (a statue is sculpted; a tree grows from a seed) and destruction or going-out-of-being (a living being dies; a chunk of coal burns to ashes); changes that are transformations in quality (the ripening peach softens) and relation (a human being becomes a parent), in quantity (a cell divides, class enrollment - you drop a course), in temporal and spatial location (you enter the lecture hall). All of them are changes. There also is variation in the dimension and ‘how’ the change occurs: change in shape, change by addition, subtraction etc.

Change in general:

In Aristotle’s analysis all change is from . . . to - - -. It always involves two types of information: An underlying, and a pair of opposites (190a.17 & 191a1).
The underlying anchors the change. The opposites provide the determinacy of the change. The opposites designate that which changes in the change. The underlying is that which remains in the change (190a.17). Aristotle thinks that, together, these are three elements (191a1). An underlying and two opposites.

The simplest example: change in quality. We buy that peach. It is hard. We let it lie for a while. It changes from hard and dry to soft and juicy. (A change in consistency). The peach is the underlying. It is the thing that changes. The opposition between hard and soft, and dry and juicy is the pair of opposites. Using these oppositions, you can analyze a change into two pairs of affirmations and negations: The peach changes from hard to not-hard, and from not-soft to soft. In each change something is lost or disappears, and something is gained or comes about.

What is the role of the underlying? Would we call ‘change’ a change without an underlying? The underlying is an Aristotelian individual thing, a substance or reality. Aristotle thinks that ‘change’ only makes sense as in ‘A changes from . . . to/into - - -.’ And that it does not make sense to say: ‘There is change from . . . to - - -, but there is nothing else, apart from that change (compare 189a29). Possible counterexamples: Change/transformation from seed into tree; pure change of color, without anything whose color it is. In the tree example the form of the tree, somehow present in the seed and determining its transformation, can serve as underlying. The color example requires that we can perceive color without perceiving it as the color of a surface or medium.

To be due to nature (Book II.):

Attention: so far we have determined ‘natural things.’ Everything that undergoes change in one or the other way, qualifies. Nature, up to now, is a class of things. Nature is the class of changing items or things. Non-nature is the class of unchanging items or things. Now a new idea enters.

Now, Aristotle adds the idea that nature is an active principle (192b20, 198b10). Nature itself is involved in change. And there is a special category of things that are ‘natures’ (pay attention to the plural) or ‘have a nature of their own’ – because they “have in themselves a source of change and staying unchanged” (192b5).

This yields a new division: things that have a source of change in themselves (things that have a nature of their own), things that do not have the source of change in themselves (e.g. artifacts). The words here used make an understanding difficult for us. Because we now have two kinds of ‘natural things’ – i.e. things that are subject to change – one of them belongs to the things that have a nature of their own, the other to things that do not have a nature of their own. Both are ‘changeables!’

Two things to understand:
(1) What is it to “have a source of change in oneself?”
(2) Why is this capacity denied to artifacts?

(1) What is it to “have a source of change in oneself?”

Easy for the seed. It is organized in such a way that it transforms. Aristotle’s idea of ‘having a source of change in oneself’ is not that one is independent from external factors for change. Nor is it that one is self-moving. The piece of charcoal that is burning to ashes in our barbecue is not self-moving, and needs igniting. But it brings to the change of burning away an organization that makes it apt to burn and to be burned into inexistence as ‘piece of charcoal.’ (A case of destruction of an individual substance). This is the internal source of change in the charcoal. There is always a contribution the thing due to nature makes to specific ways of changing. They reside in some of the features that let the reality/thing be what it is: Combustible, hard (i.e.: resisting change of shape), porous, etc. These things have in turn come about with the qualities that make them apt to specific changes. And here, the causes that make this so, are, again, the capacity of other things to contribute to change. Aristotle’s nature is thus not just the sum total of all the things that can change. It is also the web of activity in which things come about, perish, change in interaction with each other. An constantly transforming ocean of interconnected changes, including, of course, things that remain stable only because they contribute to their stability by having an inner source that prevents them from destabilizing.

But then:

(2) Why is this capacity denied to artifacts? Our tools and installations decay just as do things in ‘nature.’ But Aristotle has a specific conception of artefacts, different from ours and tied to his ideas of ‘what it is to be a determinate individual something. Recall his idea that individual substances are characterized by their essential qualities. The essence of artefacts like the house is the purpose of a thing. A house is an item that offers shelter in a durable way at a set place. That essence is there, it resides in this specific house. Importantly, the thing in front of us may decay. But the essence, which defines the thing, does not have an ‘innate tendency to change.’ Of course: the thing stops to be a house when its wood decays and its bricks decompose or its roof caves in. But this is a change which occurs to the house through a change in the underlying matter ‘brick’ ‘wood,’ etc. The change of the decaying house from being into non-being a house is not innate in its ‘houseness’character, as was combustibility in the lump of coal. The tendency to decay is innate only in the material of the house. The ‘going- out-of-being’ of the house only concurs with the decay of its material basis. Things are different only when we transform the house into something else. In that case we either swing the wrecking ball, and thereby work on the matter of the house primarily. Or we change its function and purpose, for instance by using it as a temple. In that case, the house goes out of being for us, ‘simply,’ and possibly without any change in its material basis. (The former ice-rink that has become the “University Synagogue.) But in that case too, the destruction of the ‘houseness’ of the house – that summarizes its essential trait - comes from the outside.

If there is time:

Causality and the four causes.

Causality for us:

We think of causality as a link between causes and effects. The link between the two allows us to bring about the cause, and thereby bring about the effect. Causes, in this view, are triggers (naively): Striking the match in order to light the match. The striking against the right surface is the cause for the lighting of the match. Causal explanations explain effects. We explain an effect if we are able to appeal to a law according to which whenever the cause occurs the effect will follow or co-occur. Presupposed in such explanations, as well as in the possibility to use a causal nexus is the fact that we stabilize the environment of the cause, and maintain favorable conditions in it. We want to light a match. So, not only do we need an appropriate surface, but we also need to strike with the right kind of strength, under conditions where there is not too much wind, the surface and the match are dry, etc. The law we use says that the chemical substance at the head of the match ignites when it reaches a certain temperature. An explanation why the match ignites, and the use of the match to get fire coincide: whenever we have a scientific causal explanation we can use it to bring about the effect, if we are able to bring about the cause, and to guarantee the necessary and appropriate initial conditions. Our everyday understanding of causality is effectuating causality. It links things, conditions and events with events. When someone asks: ‘why did such-and-such occur?’ we first think of searching for a cause in this sense.

Causality for Aristotle:

‘Causality’ is of course our word. Using it as a translation for Aristotles ‘aitia’ we need to treat it as if we were free to give to the term the meaning it may have had for Aristotle. He starts with a question that is different from ‘why did such-and-such occur?’
He asks: ‘On account of what?’ (194b20). And he thinks that it is a question of knowledge. Asking that question is to ask for knowledge. (Not all questions are asked for knowledge)

This is still an incomplete version of Aristotle’s question for it does not specify two things that belong to a question: It does not say where we should turn to answer the question. About what kind of item is the question ‘on account of what?’ being asked? It is, as we by now expect, primarily asked about individual substances. They are the items we are to explore looking for an answer to Aristotle’s question. Our more complete question is now: ‘On account of what is this item . . .?’

But this is still incomplete. For we have not specified what it is we want to know. Without this element a question is unanswerable. The missing element specifies the direction of the question. It determines what counts as the right answer. Our own question ‘why did such-and-such occur?’ does this by asking for the ‘why’ of an ‘occurrence’ and the implicit understanding that we want to know what preceded the effect in such a way that it was sufficient to bring about the effect in the specific environment (initial conditions). Now, Aristotle wants accounts in several kinds of respects. He asks: ‘On account of what is this item . . .?’ – and then goes on:

‘On account of what is this item a such-and-such?’ or
‘On account of what is this item constituted by/as such-and-such . . .?’ In our words: ‘What does it consist of?
‘On account of what has this item come about?’ or: ‘Who or what is the source out of which this such-and-such has come?’
On account of what is this item useful for the end such-and-such?’ ‘What kind of end has this item been meant to achieve”’
This leads to the four causes.