Mereological nihilism is the metaphysical thesis that composite objects do not exist. Formally, letting P denote the parthood relational predicate:
Pxy ↔ x = y.
When combined with materialism (as is often done), mereological nihilism entails that the only things that exist are physical simples (such as, for example, quarks and electrons). What are taken by common sense to be composite objects (sometimes referred to by philosophers as "common objects") are, according to the mereological nihilist, really nothing but various arrangements of these simples. So, for instance, a chair is nothing but a collection of simples arranged chair-wise. Similarly, a rock is nothing but a collection of simples arranged rock-wise. And so on. The reality of metaphysical substances is denied. With that being said, some forms of mereological nihilism are less radical than others. For example, the metaphysician Peter van Inwagen holds to a restricted form of mereological nihilism that allows for the existence of composite living things (e.g., plants, animals, and humans), while holding everything else to be nothing but arrangements of simples.
In this post, I want to focus on the most extreme form of mereological nihilism: the thesis that there are no composite objects whatsoever, be they living or otherwise. I also will be assuming strict materialism (i.e., to be is to be physical). I shall argue that mereological nihilism thus understood—what we might call strong materialist mereological nihilism—is incompatible with the reality of rationality and valid logical inference.
Assuming the truth of strong materialist mereological nihilism (henceforth, SMMN), human persons no less than tables, rocks, and trees, are nothing but arrangements of simples (quarks and electrons, if we are following our current understanding of particle physics); specifically, a person is nothing more than a collection of simples arranged person-wise. A consequence of this is that, if the collection of simples arranged person-wise changes configuration at all, the "person" that was identified with the preceding configuration ceases to exist and a new "person" begins to exist with the formation of the new configuration. As a result, personal identity enduring over time through change is denied by SMMN. It is this consequence of SMMN that I think makes valid logical inference impossible.
Before getting into the argument for this, however, I first want to point out that it might seem that SMMN is just obviously wrong since it implies that "I" do not exist from one moment of time to the next (assuming, that is, that the arrangement of simples that "I" am identical to undergoes change during that time), and this is utterly contrary to my conscious experience. The way that SMMN defenders get around this is by pointing out that while it is true that there is no enduring "you," nevertheless, the collection of simples arranged person-wise retains memories from one configuration in time to the next, and this is how it is that one can experience a sense of self-identity over time. This experience, however, it not veridical; the sense that one endures through time is an illusion of conscious experience.
While the foregoing alone will be enough to turn some people away from SMMN, I now want to sketch an argument for why SMMN cannot possibly be rationally affirmed as true by anyone. In order for a person (here, I am using the term "person" in a metaphysically neutral sense; the defender of SMMN should feel free to read "person" as "a collection of simples arranged person-wise") to rationally come to believe in SMMN, he must be able to logically reason through the premises of an argument for SMMN so as to arrive at the truth of SMMN as the conclusion. (As an aside, it is plausible that not all knowledge is discursive in the sense that it is the result of making logical inferences. Some knowledge is immediate such as the immediate knowledge that one is "being appeared to redly" when one perceives the color red. With that being said, I think it is pretty clear that the knowledge of SMMN cannot be construed in this way. It is a metaphysical thesis quite removed from, and even contrary to, common sense. As such, if someone is going to arrive at the knowledge that SMMN is true, one must do so discursively by making logical inferences).
Now, it is necessary for the possibility of valid logical inference that a single subject reasons through, for example, the premises in a deductive argument to the conclusion by way of applying one or more logical rules of inference. To make this a bit more concrete, consider the following stock argument, which I will simply refer to as "the argument" in what follows:
- If Socrates is a man, then Socrates is mortal.
- Socrates is a man.
- Therefore, Socrates is mortal.
The conclusion (3) follows by modus ponens from the premises (1) and (2). Now, in order for someone—let's call him Patrick—to validly reason from the premises of this argument to the conclusion, he must entertain each of the premises and accept them as true and then apply modus ponens to the premises in order to derive the conclusion, and then (seeing that the conclusion logically follows from the premises) he must accept the conclusion as true. If Patrick only entertains and accepts as true the first premise of the argument but not the second (or vice versa), he will not validly arrive at the conclusion. Or, if Patrick simply accepts the conclusion without having considered the premises and without having applied modus ponens, he will not have arrived at the conclusion by way of valid logical inference. Rather, he will have simply accepted the conclusion wholly independently of a valid logical deduction.
Now, consider three times t1, t2, and t3, such that t1 < t2 < t3. On a metaphysical view that affirms the reality of metaphysical substance and the endurance of personal identity over time, Patrick can validly reason through the argument. At t1, Patrick entertains and accepts as true the first premise. At t2, Patrick entertains and accepts as true the second premise. Then, at t3, Patrick applies modus ponens and arrives at the conclusion, which he then accepts as true.
The trouble with SMMN is this: Patrick, according to SMMN, is identical to a particular configuration of simples. Patrick is really just the name we give that denotes this particular configuration of simples (in this way, SMMN can be seen as a radical form of nominalism). Now, either this configuration of simples does not change at all over the time interval [t1, t3] or it does change. If it doesn't change, then Patrick cannot validly reason through the argument because he cannot do anything at all. He is essentially frozen because he is identical to the configuration of simples, and we are supposing that the configuration does not change over the time interval in question. If, instead, the configuration of simples changes, then Patrick still cannot validly reason through the argument because Patrick only exists at t1. At t2, because the configuration changes and gives rise to a new configuration and (per SMMN) Patrick is identical to the preceding configuration, Patrick no longer exists at t2. Instead, Patrick* begins to exist at t2. Similarly, Patrick* ceases to exist at t3, and Patrick** begins to exist at t3. So, while Patrick might entertain and accept as true the first premise of the argument, he isn't around at t2 to entertain and accept as true the second premise. And Patrick* can entertain and accept as true the second premise, but he has not entertained and accepted as true the first premise, and he will not be around at t3 to apply modus ponens to both premises of the argument. And Patrick**, not having accepted the first two premises, does not validly reason through the argument either.
So, none of Patrick, Patrick*, or Patrick** can validly reason through an argument. In general, SMMN entails that no one can validly reason through an argument. In particular, SMMN entails that the mereological nihilist himself cannot validly reason through an argument for SMMN itself. Thus, any argument for SMMN is necessarily rationally self-undermining; it is impossible to rationally affirm SMMN. For this reason, therefore, SMMN must be rejected.
In the remainder of this post, I will consider several possible objections that a defender of SMMN could raise against this argument.
Objection 1: While it is true that a single subject (e.g., Patrick) does not endure over time, nevertheless, because the configuration of simples at, for instance, t3 preserves most of the same memories that were constituted by the configurations of simples at t2 and t1, respectively, there is enough continuity in the memories of Patrick, Patrick*, and Patrick** for a valid logical inference to be made. As long as the reasoning process terminates in Patrick** believing the conclusion, the reasoning process is valid. The proponent of SMMN can simply hold that in order for a reasoning process to be valid, the entire process does not have to be carried out by a single, enduring subject. Rather, the reasoning process can be distributed over different configurations of simples. This is admittedly very bizarre, but the proponent of SMMN is willing to bite the bullet and accept what is very bizarre.
Response: This objection is inadequate for multiple reasons. First, memories do not reason through arguments, persons using memory reason through arguments. And since SMMN entails the falsity of personal identity over time (since a person is nothing but a particular configuration of simples), persons simply cannot reason through an argument (since such reasoning always takes some amount of time). Second, if memories being retained and largely shared by multiple, distinct configurations of simples is supposed to be sufficient for valid logical inference, then we have the following problem: Suppose there are three people: Socrates, Plato, and Aristotle. And suppose they have been conjoined as triplets since birth. Consequently, they have experienced all of life together, and their memories are very similar, almost the same even. Now, suppose Socrates entertains and accepts as true the first premise in the argument; Plato entertains and accepts as true the second premise in the argument; finally, Aristotle entertains and accepts as true the conclusion of the argument. Now, if three different things (three different configurations of simples) having almost the same memories is a sufficient basis for validly reasoning through an argument, then it seems we must conclude that Aristotle has validly reasoned through the argument. But he has clearly done no such thing. He has merely accepted the conclusion without having considered either of the premises and without having applied modus ponens. But if Aristotle has not validly reasoned through the argument, then neither has Patrick**. Or, if we insist on distributing the reasoning process over the three configurations collectively, then we would have to say that, if Patrick, Patrick*, and Patrick** collectively validly reason through the argument, then so do Socrates, Plato, and Aristotle. But this, too, is clearly not the case because the beliefs of Socrates, Plato, and Aristotle bear no logical relations to each other.
Moreover, given SMMN, on what basis would we even say that Socrates is different from Plato, or that Plato is different from Aristotle? It seems quite clear that these are distinct, individual entities, but on what basis could we say this if we are assuming the truth of SMMN? Given SMMN, the only things that really exist are the simples. Composite objects are simply arrangements of simples. But why should we treat Socrates as one arrangement of simples and Plato as another, distinct arrangement of simples? It seems we can with equal justification simply consider the mereological fusion of Socrates + Plato as a single configuration of simples. Given SMMN, there does not seem to be an adequate principle of individuation for collections of simples. Two collections can just as easily be understood as one collection. In fact, all of the simples in existence could be conceptualized as one single giant configuration. The upshot of this is that SMMN seems to at once imply an extreme form of pluralism over time and an extreme form of monism at a time. In short, SMMN seems to make reality unintelligible.
Objection 2: The foregoing counterexample to the previously proposed SMMN solution to the problem of valid logical inference involving Socrates, Plato, and Aristotle does not succeed. For there is a crucial difference between the "reasoning process" of Socrates, Plato, and Aristotle, and the reasoning process of Patrick, Patrick*, and Patrick**: the reasoning process of the latter is constituted by a causal relation, whereas that of the former is not. And this makes all the difference.
Response: It is difficult to see how this could make all the difference. First, the scenario involving Socrates, Plato, and Aristotle can be modified so that there is a causal relation involved. For instance, we can suppose that when Socrates accepts as true the first premise of the argument, he holds up a paper with the second premise written on it for Plato to see. Upon seeing the second premise, Plato accepts it as true. Plato then holds up another piece of paper, this time with the conclusion written on it, for Aristotle to see. Upon seeing the conclusion, Aristotle accepts it as true. In this way, Socrates' belief in the first premise causes him to perform an action which causes Plato to believe the second premise, and Plato's belief in the second premise causes him to perform an action which causes Aristotle to believe the conclusion. In this revised scenario, the "reasoning process" of Socrates, Plato, and Aristotle is constituted by a causal relation and yet it is clear that a valid logical inference has not taken place. For Aristotle does not believe the conclusion due to having applied modus ponens to the premises. Second, the causal process involving Patrick, Patrick*, and Patrick** is either deterministic in a classical way or indeterministic in a quantum way. If it is deterministic, then Patrick** is causally necessitated to believe the conclusion of the argument. The conclusion is not arrived at by way of a rational, deliberative process. Whether or not a rational process took place, Patrick** will accept the conclusion. The conclusion, therefore, is not arrived at by way of valid logical inference. If instead the causal process is indeterministic, then Patrick** believes the conclusion at random (since genuine free will is, or so I would argue, incompatible with SMMN), and this is also obviously not compatible with valid logical inference. Either way, therefore, I conclude that a causal process is not sufficient for a rational process. A causal relation is not sufficient for a logical relation.
Objection 3: A causal process (deterministic or indeterministic) can be a rational process if it is, for instance, a computational process. Consider: Patrick*'s state of belief in the second premise of the argument is caused by Patrick's state of belief in the first premise, and Patrick**'s state of belief in the conclusion is in turn caused by the preceding states of Patrick and Patrick*. Now, we can understand this causal process as the execution of a kind of computer program that implements the algorithm for modus ponens and that executes by way of transitioning from one computational state to the next (where each computational state corresponds to a particular configuration of simples) until the end state is finally reached and the execution of the program terminates with the correct output (the configuration of simples that is identical to Patrick**). In this way, the evolution of the configuration of simples over the time interval in question effectively implements the algorithm for modus ponens just like an everyday electronic digital computer might run an algorithm for modus ponens, with the input being the premises of the argument and the output being the conclusion. Thus, the thesis of computationalism helps to fully flesh out the SMMN theory of valid logical inference. If the causal process is deterministic, we can understand it as implementing a classical computation; if instead it is indeterministic, we can understand it as implementing a quantum computation.
Response: First and foremost, I think there are very strong reasons to reject computationalism in general. I lay out such reasons in my published work HERE. Second, the defender of SMMN is surely going to want to distinguish between arrangements of simples that are rational and arrangements of simples that are not. For instance, a collection of simples arranged person-wise is rational, while a collection of simples arranged rock-wise is not. Now, ultimately, unless the defender of SMMN wants to countenance panpsychism (the thesis that everything is conscious and possibly even rational), he is going to have to hold that the simples themselves are not rational. Rather, rationality is to be understood as an emergent phenomenon that arises from a collection of simples forming some sort of arrangement. But this means that prior to some particular arrangement of simples, there is no rationality. So, by whatever process brings about, for instance, a person-wise arrangement of simples, that process can't be rational. But if that process is not rational, then we have no reason to trust that anything produced by that process is rational. Hence, we have no reason to think that a person-wise arrangement of simples is rational, i.e., we have no reason to think that we ourselves are rational. To adopt the computationalist paradigm, we have no reason to think that the computer programs that constitute our rational faculties were not written by monkeys. (I highly doubt that a defender of SMMN would be willing to countenance the existence of an intelligent Cosmic Programmer). Therefore, once again, SMMN leaves us in total skepticism, and thus any argument for SMMN is rationally self-defeating.
Objection 4: The theory of evolution furnishes us with a paradigm that explains how a non-rational process can ultimately produce a rational process. The basic idea of evolutionary theory is that simple organisms evolve over a long period of time into complex organisms (descent with modification) by way of random mutations. However, only the organisms that are capable of surviving pass on their traits to succeeding generations. The organisms that lack traits with survival value die off and do not pass on their traits to succeeding generations. In this way, nature "selects" traits with survival value (natural selection). Traits with survival value are called adaptive. Now, it is apparent that collections of simples arranged person-wise have beliefs. And it is clearly the case that having true beliefs is very conducive to survival. Thus, having reliable cognitive faculties that tend to produce true beliefs is very conducive to survival. We would expect, therefore, for the trait of having reliable cognitive faculties to be "selected" by the process of natural selection. So, we may conclude that SMMN, when paired with evolution, can account for the reliability of our cognitive faculties and hence of our ability to validly reason.
Response: While it is certainly the case that true beliefs have high survival value, it is nevertheless true that false beliefs can have survival value just as high. It seems that for any true belief that is adaptive, a false belief that is just as adaptive can be given. For example, suppose that I am in the wilderness, and I see a lion and form the true belief that lions are dangerous and can easily kill unarmed humans, which causes me to run away from the lion to get to safety. It is clear that this belief is adaptive because it will serve to get me away from the lion so that I can survive and pass on my genes. But consider a false belief that is just as adaptive: I see the lion and form the belief that I'm late for a business meeting (and there is no such business meeting) that is in the opposite direction from the lion, which causes me to run away from the lion, and this just happens to bring me to safety. It is clear that this belief, though false, is adaptive because it too will serve to get me away from the lion so that I can survive and pass on my genes. In general, for any true belief that is adaptive, a false belief can be given that is just as adaptive. Hence, since the only thing natural selection cares about is survival, there is no more reason to think that any given belief produced by our cognitive faculties (which have themselves been produced by evolution) is true as opposed to false. By the principle of indifference, therefore, we ought to assign a uniform probability distribution to the possible truth values of any given belief. So, whether a given belief of ours is true or false is 50/50. Given this, the probability that many of our beliefs are true is very low. If we imagine a mere 100 beliefs that are held independently of each other, the probability that they are all true is (1/2)100, a very small number. (This is, in a nutshell, Alvin Plantinga's evolutionary argument against naturalism). Therefore, far from SMMN paired with evolution being able to account for the reliability of our cognitive faculties, SMMN paired with evolution actually leads to the conclusion that our cognitive faculties are not reliable at all. Therefore, SMMN remains rationally self-defeating.
Objection 5: Perhaps, given all that has thus far been said, the SMMN defender should just embrace eliminative materialism and deny the existence of beliefs altogether.
Response: You expect me to believe that? 😎
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