Some philosophers of science have suggested that scientific discussions of “reductionism” and “emergentism” are merely rhetorical funding grabs. But drawing together my work in earlier parts of the book, in the final section, Part IV, I outline how we are in substantive, ongoing and empirically resolvable scientific debates about the structure of scientific cases of compositional explanation from superconductors to the eusocial insects shown in the picture above. In this post, I briefly highlight the live positions in our new debates, the empirically resolvable issues between them, and how and why the debate is ongoing in various concrete scientific cases. Once again the post is compressed, but I hope it may convince you they are interesting issues to explore.
Let me note some important tidying-up I begin by doing in Part IV. For one might ask why I am bothering with scientific reductionism if I take its most prominent argument, in the simple parsimony reasoning using the existence of compositional explanation, to be invalid? The answer is that I return to my findings about scientific reductionism to illuminate a valid argument for compositional reduction in a case of compositional explanation. This reasoning is based around the applicability of compositional concepts plus what I call the ‘determinative completeness’ of components in a case – basically the claim that the relevant components are only determined by other components. I term this the ‘Argument from Composition and Completeness’, but I highlight how this new reasoning has far, far higher evidential requirements than the invalid Argument from Composition.
Secondly, I use what I term the ‘Argument from Exhaustion’ to formally establish that machretic determination is required, whether alone or in concert with other forms of determination, in order for a composed entity to be determinative. I consequently confirm that in order to exist a compositional relation must always be accompanied by a machretic relation. And I also thus establish that Mutualism is plausibly the only viable ontologically non-reductive position about the structure of a case of compositional explanation or about nature itself.
With these two arguments in hand, as well as earlier findings, I then offer a brief survey of which positions about a case of compositional explanation are live and which are dead. To begin, I show that the most popular positions in science and philosophy, in positions built around the Scientifically Manifest Image or standard forms of non-reductive physicalism, are dead positions that we can now see must collapse into other views. In contrast, I show that there are three live positions in the Mutualism of scientific emergentism and two versions of the Fundamentalism of scientific reductionism.
In our new debates, there are two broad layers of ontological disputes. The first, and more familiar, set of differences concerns the range of determinative entities, the kinds of determination we find in nature, and hence the overall structure of cases of compositional explanation. On one side of these disputes, there is the Fundamentalism of scientific reductionism that subtracts compositional relations and levels to leave us with a universe that has one layer of determinative entities, but alongside a rich macro-world involving their collectives and higher sciences that study them. On the other side of these disputes, one can embrace the Mutualism of scientific emergentism where we do have walls of compositional relations rising vertically upwards in the house of nature, but only alongside the addition of a solid roof of machretic relations pressing downwards from composed entities to components. The Scientifically Manifest Image is not amongst the viable positions, nor are the standard versions of non-reductive physicalism defended in philosophy, since I show that the only live options involve either adding to, or subtracting from, the ontological accounts of these popular positions.
On top of this first set of disputes, my work also illuminates that in the new era focused on collectives we have a second layer of ontological differences that has been largely overlooked by philosophers and which has been left implicit even in scientific debates. This second set of disputes focus on differences over the continuity/discontinuity of nature and, in particular, the continuity/discontinuity of aggregation across simpler and more complex collectives. Central to these disagreements are differing epochal assumptions in the opposing Simple and Conditioned views of aggregation, outlined in the last post, and held by scientific reductionists and emergentists.
My work shows this second set of disputes does not neatly line-up with the first set of issues and leaves us with a still more complex set of live positions. I highlight this situation by illuminating a final overlooked position in a species of Fundamentalism that follows Mutualism in embracing discontinuities in aggregation, and hence the Conditioned view of aggregation and the existence of differential powers, whilst still endorsing the determinative completeness of components and pressing parsimony arguments to show that component entities are the only determinative entities. I thus distinguish this overlooked position, in what I term ‘Conditioned’ Fundamentalism, from the Fundamentalism commonly held by scientific reductionists like Weinberg and many in philosophy that I label ‘Simple’ Fundamentalism. Crucially, Conditioned Fundamentalism offers a live, and often very plausible, account of the components in the complex collectives in actual cases of compositional explanation.
In this second set of disputes about concrete scientific cases, we thus have Simple Fundamentalists on one side pressing the continuity of nature, the non-existence of differential powers of components, and the truth of the Simple view of aggregation. However, on the other side of this dispute, we have two positions in Mutualism and also Conditioned Fundamentalism that endorse discontinuities in aggregation, the existence of differential powers of components and hence the truth of the Conditioned view of aggregation. However, these two views then themselves diverge over other issues. Crucially, Mutualism and Conditioned Fundamentalism differ over what entities determine the novel behaviors and differential powers of components, where the Mutualist claims ‘emergent’ composed entities machretically determine these contributions and the Conditioned Fundamentalist claims other components determine these contributions.
This abstract survey begins to draw out the nature of the three live views and the more complex array of disputes between them over the nature of concrete scientific cases were we have compositional explanations. But I also directly focus on the import for cases of compositional explanation of the three live views.
The negative conclusions of this detailed work confirms that debates in the new era of collectives have moved on from the issues of the last generation of debates that too many scientists and philosophers often still focus upon. Writers on both sides, including those who have hit on one of the live views, continue to take their opponents to hold views from the last generation of debates. But my work throughout the book shows that our present disputes do not concern any of the following: whether we can supply a compositional explanation in the case; whether compositional concepts apply comprehensively in the case; whether there is multiple composition in the case; whether we may need to posit higher level scientific explanations to capture all the truths about the case; whether we may need to use non-linear dynamics or explanation by simulation; whether feedback loops exist, amongst other issues. My work shows that all the live views in the new debates, both reductionist and emergentist, are agreed about all of these phenomena and that our discussions in the sciences have moved on.
In contrast, my positive work clarifies how the three live views do differ over a finer grained array of ontological issues in any case of compositional explanation. Broadly put, the hypothesis of Simple Fundamentalism is that, underneath all the semantic and epistemic complexity, aggregation really is continuous and we have no differential powers of components in complex collectives, the Simple view of aggregation applies to the case, and we only have component entities and the determination between them. In contrast, the hypotheses of Mutualism and Conditioned Fundamentalism both assert that aggregation is discontinuous, that components have differential powers in the relevant complex collective and hence that the Conditioned view of aggregation applies in the case. However, Mutualism and Conditioned Fundamentalism differ over the entities that determine the differential powers of components, the nature of the determinative entities and the species of determination we find in the case.
Building on this work, I then articulate particular ways to empirically confirm or disconfirm the three live hypotheses about the structure of a case of compositional explanation. I show that the hypothesis of Simple Fundamentalism may be confirmed or disconfirmed by resolving whether components have differential powers using the usual scientific methods by which we illuminate causal relations and hence powers. Assuming that we have found there are differential powers in some example, I outline how we may confirm or disconfirm the hypotheses of Mutualism and Conditioned Fundamentalism by resolving whether the contribution of differential powers by components is determined by composed entities or by other components. Once again, I note that common scientific methods plausibly suffice to supply such findings. Overall, I therefore outline how the issues of the new debates are empirically resolvable and my work clarifies how to break the present stalemate in these discussions using scientific methods.
I use my findings, in Chapter 10, to provide an assessment of what has been established so far from our empirical evidence. I therefore survey extant defenses using empirical evidence from both sides of the debates, in philosophy and the sciences, and focusing on cases from across the higher and lower sciences ranging from quantum mechanical derivations of chemical phenomena and the nature of superconductors, at one extreme, through to the nature of the ants shown in the picture above, and other eusocial insects and their colonies, at the other.
On the positive side, my work shows that a range of philosophers, and scientists, have now made plausible cases that in some examples we have, or are close to getting, the kind of empirical evidence that satisfies the threshold of evidence I argue is needed to resolve the new debates. However, on the negative side, I show that each of the extant defenses is plagued by the theoretical problems I have identified and hence plausibly fails due to one or both of two problems.
The first kind of difficulty I highlight in extant defenses is that, contrary to the claims of their protagonists, once we understand the empirical evidence relevant to our ongoing disputes, then we often simply find that we do not yet have the kinds of evidence in examples passing the necessary threshold.
In addition, the second problem I identify with extant defenses is still more important because it bites even when we do have sufficiently detailed evidence of the right kind. Crucially, for the reasons highlighted in earlier Chapters, I show extant defenses fail to engage their strongest relevant rivals or the key issues with them. But scientific theory appraisal is comparative, so extant defenses are unsuccessful because they have so far failed to engage relevant rival hypotheses and the key disputes with them – even in cases where I suggest we may well already have evidence meeting the threshold for productively engaging these disputes.
My final conclusion is consequently that, at least as yet, it is still very much an open question whether we should accept either version of Fundamentalism, or instead endorse Mutualism, about any of the particular scientific examples where the proponents of such positions are presently battling across physics, chemistry, biology and the sciences of complexity. My work therefore shows that, far from being mere rhetoric, recent scientific battles over reduction and emergence involve competing, substantive scientific hypotheses that differ over the nature, and structure, of concrete cases of compositional explanation in the sciences in empirically resolvable ways.
Our new debates are thus plausibly important, and ongoing, scientific debates. And my final conclusion is that, just as Laughlin claims, we have indeed moved into a new era, and one focused on collectives and their components, but that it still remains to be established whether the scientific reductionist or emergentist is correct about cases of compositional explanation across an array of levels and sciences. Still more exciting, my work shows how to resolve these presently stalemated disputes and that we may already have the evidence to hand that allows us to do so once our better theory allow us to marshal it properly. I also identify an array of important theoretical questions that urgently need to be addressed. There is thus much still to do for scientists, and philosophers, interested in reduction, emergence and the structure of nature.