Are some parts of reality more fundamental than others? Physics is often said to be more fundamental than biology, because the physical facts are thought to explain the biological facts. But is the world really divided into levels in this way? Naomi Thompson argues that, in fact, we project this structure onto reality, rather than discovering it there. This structure tells us about our ways of understanding and explaining the world, but it does not tell us about reality as it is in itself.
Are universities, chairs and tables, money, and viruses real? On the one hand it seems that they are – we can study at university, thump our fists onto tables, exchange money for food and develop treatments (or fail to do so, with devastating consequences). But on the other hand, these things all seem to depend on other things: universities are plausibly nothing more than the buildings they are located at, the staff that work at them and the students that populate them; chairs and tables are made up of molecules of various kinds; for something to be money seems to depend somehow on our collective decision-making; and viruses are just groups of proteins working together. If these things can be fully explained and accounted for in terms of the things they depend on (as plausibly they can) then perhaps only what they depend on is really real. And if, for example, the chairs and tables are ultimately just made up of subatomic particles, perhaps those are the only things that are really real?
Since (at least) William of Ockham in the 12th century, philosophers have been concerned not to multiply entities beyond necessity: best not to believe in anything more than you need to believe in to get the job done. So if you can explain everything in terms of fundamental physics, maybe you don’t need to believe in anything else. But it does really seem as though there are lots of truths beyond those of fundamental physics, and lots more things than subatomic particles! By taking seriously the idea that some things depend for their existence and their nature on other things, we can both indulge our taste for ‘desert landscapes’ – for not wanting to commit ourselves to more than we have to – and our sense that reality is not like a desert at all. The key is to think that only the fundamental things – the things that don’t depend on anything further – really count; everything else comes ‘for free’.
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If the structure of reality was totally different to how we think it is, it seems likely our beliefs about it would be unchanged.
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But what of these dependence relations themselves? Are they really real? And what follows if they aren’t? We can think of these dependence relations that purportedly structure reality as like a kind of ‘metaphysical causation’. Just as causal relations relate causes and effects over time, this structuring relation – which contemporary philosophers call grounding – relates things over levels of reality. And just as Hume was suspicious of ‘necessary connexions in nature’ when thinking about causation, we might be suspicious of such necessary connections when we think about the relationship between the (more) fundamental and the (more) derivative. We shouldn’t lose sight of quite how strong a claim it is to say that once we settle what exists at the fundamental level of reality (say, physics) the rest of reality simply unfolds by itself, but many contemporary philosophers (e.g. Kit Fine; Jonathan Schaffer) do claim this.
Alongside the ‘metaphysical’ worries about the kind of thing that grounding is, we might also worry about the epistemology of grounding – about how it is that we can come to know about grounding relations. Grounding isn’t the kind of thing we can experience or test experimentally. In fact, if the structure of reality was totally different to how we think it is, it seems likely our beliefs about it would be unchanged. Some contemporary philosophers (e.g. Jonathan Schaffer) and some historical figures like Spinoza, for example, take very seriously the idea that what is fundamental is not the smallest bits of reality after all (philosophers use the term ‘atoms’ to mean whatever cannot be further divided), but the largest sum; the entire cosmos. Trying to settle who is right doesn’t involve trying to find out about metaphysical structure directly, but involves looking at other sorts of theoretical commitments held by the participants in the debate. Knowledge of whether grounding relations exist, what they are like, and what precisely grounds what all seems somewhat hard to come by.
Grounding is taken to be an explanatory relation: if facts at the level of physics ground and hence determine the chemical facts, they also explain them. In response to worries about the epistemology of grounding, philosophers have suggested that we can get to know about grounding by thinking about the nature of explanation and about what we take to explain what. But grounding is supposed to be an objective, mind-independent relation that structures reality, while plausibly something only counts as an explanation if, for example, somebody comes to understand what is being explained on the basis of that explanation. If that’s right, then the nature of explanation seems a poor guide to the nature of grounding, because what counts as an explanation is partly determined by what sorts of things we humans find explanatory – on, for example, whether it leads to understanding – whereas whether something counts as a grounding relation isn’t so constrained.
Given the general affinity for desert landscapes mentioned above, we shouldn’t commit ourselves to believing in any metaphysical posits that go beyond what is required to ‘get the job done’. And we don’t seem to have any direct knowledge or experience of grounding relations. But thinking about reality as structured by grounding relations is what allows us to make the distinction between the fundamental and the derivative, and so maintain our taste for desert landscapes whilst explaining the existence of all of the things we take to exist. So, can we get the benefits of thinking about reality in terms of metaphysical structure, but without committing to thinking that mind-independent grounding relations exist? I think we can, by being antirealists about grounding.
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Metaphysical structure isn’t part of reality as it is in itself. It is projected onto reality by us.
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Antirealism about grounding means denying that these relations that structure reality exist mind-independently. Instead, we can think of grounding as a useful fiction that helps us to make sense of the world, guides our investigation, and enables us to express what we take to explain what when we’re thinking about reality at a very general level. This doesn’t mean we should stop talking about grounding and about metaphysical structure altogether – quite the opposite. By recognising the helpful roles that thinking and talking about grounding can play, we can legitimise continuing to talk in those terms. By denying that grounding is part of mind-independent reality, we avoid the concerns mentioned earlier about the nature and the epistemology of grounding. If we don’t think of grounding as part of mind-independent reality, we can hold on to thinking of it as closely connected to explanation, and to thinking of whether something counts as explanatory as depending, at least in part, on whether we can come to understand something on the basis of the explanation offered. Metaphysical structure isn’t part of reality as it is in itself. It is projected onto reality by us.
It's important to recognise that this doesn’t mean that just anything can count as a metaphysical explanation. We can insist, for example, that whatever is supposed to do the explaining must be true. Most of us would agree that this rules out, for example, astrological facts to do with people’s star signs featuring in explanations of facts about their love lives (even if some people feel they gain understanding on the basis of such purported explanations).
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Reality’s structure is dependent on us, but it is there nevertheless.
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So where does this leave us? One might think that antirealism about metaphysical structure implies that the world is ‘flat’ – nothing depends (in the general sense at issue) on anything else. I think this would be a mistake. Reality’s structure is dependent on us, but it is there nevertheless. We can continue to reap the benefits of thinking and talking in terms of structure and fundamentality so long as we remember that structure is projected, not discovered. We can continue to indulge our taste for desert landscapes while affirming the existence of chairs, tables and viruses, and can do so while avoiding the worries about the nature and the epistemology of structure. If we instead reject grounding altogether, we will need either to deny that these things exist, or put up with taking reality to be densely populated.
The picture we end up with is not the radical antirealism we might at first seem to. Antirealism about structuring relations doesn’t have to lead to antirealism about the entities they relate: we can be antirealists about the grounding relations between the chemical facts and the physical facts, for example, without being antirealists about the chemical facts (or the physical facts). But the idea that structure is dependent on us implies that our role in making and ordering the world is significant. This amounts to a moderate version of internal realism as defended at times by Hilary Putnam, which itself takes root from a kind of Kantian transcendental idealism. Both mind and world have a part to play in making up the world.
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