Metaphysics vs Explanations and Intelligibility

Another objection to my initial formulation of the problem is that I framed the question in terms of the structure of bodies. Do all of an object’s properties flow from its essence or are some artificially added on by God? Some, however, might suggest that it is wrong to organize the debate around metaphysical questions. Instead, the debate should focus on questions about the special intelligibility of mechanical properties.76 On this view the question should be formulated as follows: “Are all natural phenomena understandable in terms of the mechanist hypothesis? Or are some not susceptible to mechanistic explanation and therefore non-naturally superadded?” I think that this way of framing the question has some serious shortcomings.

73 _{I think that the question of whether or not he did, like the question about whether or not he accepted the}

mechanist hypothesis, is an extremely difficult question. And, I think these questions have to be indexed to various stages of Locke’s intellectual development.

74 _{And indeed, when one looks at Locke’s introduction of the concept of a real essence at 2.31.6 he uses the}

term to refer to whatever internal constitution of an object is thought to give rise to its observable properties. He does not confine the use of the term to corpuscular sub-structures.

75 _{For Locke’s exposure to Glisson see Rogers 2008, note 32.}

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One place to begin might be to note a distinction between what is mechanistically intelligible to us given our current epistemic state and what is in-principle mechanistically intelligible. If our concern is with the former then there will be very little to debate. Locke clearly believed that mechanism had a special intelligible status for us. And Locke clearly believed that there were limits to the intelligibility of mechanism.77 So, if the debate about whether there are superadded properties is just a debate about what sort of phenomena are, at present, intelligible to us then there should be no disagreement.

If our concern is with the in-principle intelligibility, however, the debate reopens. Some might argue that all phenomena (including gravitation and thinking matter) are in- principle intelligible as mechanical phenomena. It is only our current epistemic limitations which prevent us from understanding how these phenomena are produced mechanistically. Others, however, might argue that no matter what epistemic position we are in there can never be a mechanical explanation of gravitation or thinking matter; they are necessarily non- mechanistic phenomena. My hope is that the arguments in this chapter are sufficient to show that Locke thought that neither of these positions is correct. If the debate is about whether mechanistic explanations of all phenomena are in principle available I think Lockean humility demands an agnostic answer.

So it seems to me that an emphasis on the special intelligibility of mechanism will not go very far toward a better approach to questions about superaddition. Before leaving the topic, however, I think there are two questions which are worth addressing. 1) Does the

77 _{See Downing 1998, especially Section 3, for a good discussion of this special intelligible status and its limits.}

In this paper Downing declines to discuss superaddition in detail (page 409: What superaddition amounts to for Locke and how God is supposed to accomplish it is a perplexing question which we can, fortunately, skirt”). Nevertheless, I think that the arguments I have presented in this chapter are, in large part, amenable to the position she develops there.

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special intelligibility status of mechanism have any impact on our understanding of scientific phenomena? 2) Why did Locke think mechanism had a special intelligibility status? I will consider these questions in order.

Should the special intelligibility of mechanism determine how we think about the metaphysics of material objects and their causal interactions with other objects? I think those who want to organize the superaddition debate around questions of intelligibility must

answer yes to this question. Further, I think it is easy to see why they would want to do so. A very natural thought is that if mechanism is particularly intelligible to us we have very good reason for thinking that the world is organized mechanistically. And if the world is organized mechanistically then the existence of phenomena like gravitation and thinking matter are particularly troublesome. They do not cohere with our picture of how the world is organized and so we have reason to think that they come from non-natural superadded properties of bodies.

The problem with this line of thought is that it relies on an inference to best

explanation (IBE). The line of argument says that because mechanism is intelligible to us, and more intelligible than any other scientific view, we have reason to think that the world is mechanistic.78 Whatever the status of IBE arguments in contemporary philosophy, a major goal of this chapter has been to show that IBE is an invalid form of argument for Locke. For Locke, there is a major gap between intelligibility and the world (or, put differently, between intelligibility and either possibility or actuality). God, when making the world, did not have human intelligibility in mind. So whether or not something is intelligible to us does not bear on the question of what that thing is like (how it was made by God).

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What should we infer from the fact that various phenomena are unintelligible to us? Clearly we have no warrant for assuming that these phenomena are, in fact, compatible with the intelligible mechanistic hypothesis. Equally clear, however, is the fact that we have no reason for dogmatically asserting that they are incompatible with the mechanistic hypothesis and therefore non-naturally superadded by God. The only appropriately humble lesson to draw from the unintelligibility of certain phenomena is that we do not know how those phenomena are produced.

Recall the second interesting question about the special intelligibility of the mechanist hypothesis: Why did Locke think mechanism had a special intelligibility status? What sets mechanism apart from other theories? Now, once we understand that the intelligibility of mechanism is irrelevant to the question about superaddition (once we answer the first question) this second question might lose some of its interest. The answer to this second question will not affect our views about superaddition. Nevertheless, it is worth noting that the arguments given in this chapter might offer us some insight into why Locke thought mechanism was particularly intelligible.

The mechanist hypothesis, in its 17th century manifestation, was designed by analogy to the observable mechanical properties of ordinary objects. The operations of micro-level corpuscles were explained through this explicit analogy to the operations of macro-level objects. Recall from above Locke’s account of the proper function of our faculties (including our intellect). Their foremost purpose was allowing us to survive in the material world: not getting bitten by tigers, cutting the skins off fruit to eat the insides, taking cover when it rains, etc. According to Locke we were specifically designed to understand medium-sized dry goods and how to manipulate them. Given this, I think we can establish two things.

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First, it is not at all surprising that the mechanist hypothesis, because designed to be

analogous to macro-level objects, is highly intelligible to us. Second, while our best shot at conceptualizing what the micro-level is like might be to understand it mechanistically this will not help us know the nature of the micro-level. So I think there is no reason to frame the debate about superaddition in terms of the intelligibility of mechanism instead of framing it in terms of natural vs. non-natural properties.

8. Conclusion

The goal of this chapter has been to argue that Locke was agnostic on the question of superaddition. Locke held that there were severe epistemic limits to our knowledge of the natural world. As a result of this, we are simply unable to tell which properties of bodies are natural and which are non-natural. The arguments in this chapter also show that no matter how we formulate the problem of superaddition any debate on the topic will be defective. Again, Lockean humility demands agnosticism.

Perhaps we should be disappointed with Locke’s agnostic response to the question of superaddition. It is, after all, the “easy” way out of a fascinating and difficult problem. But perhaps Locke’s agnostic response is also fitting. The Essay is a work of epistemology, not a work of metaphysics. Or, to put the point more clearly, the Essay is a book about us, about the human understanding, and not a book about the world and its contents. As such, it is only fitting that Locke confined himself within the limits of his subject matter.