Where It’s Useful
I’m a big fan of simplicity in principle but with one major caveat.  Except for a two-year break to study theology, I worked about 40 years as a design engineer designing machines, systems, and software. In that work, simplicity was an important goal. Simpler designs are less costly, easier to manufacture, maintain, and generally more reliable.  The fewer “moving parts” in a machine, system, or software the less likely there will be problems with it. But here’s the major caveat. The design had to work.  It had to meet the specifications even if that required more complexity.

This goal of simplicity could be broadly understood under the concept of parsimony. One of the most generally recognizable ways of characterizing parsimony is Occam’s Razor, named after English Franciscan friar William of Ockham (c. 1287–1347).  Often the Razor is summarized in sentences like: “Entities should not be multiplied without necessity”, or the one most likely attributable to Ockham himself, “Plurality must never be posited without necessity”. The one I particularly like is probably a paraphrase of what Einstein actually said. It goes: “Everything should be made as simple as possible — but not simpler.” The key point in these is that necessity should guide how simple or complex a theory or system should be.  So what determines the necessity?

Let me offer an example from my work.  When I worked in the aerospace industry, specifications for a system often had hundreds of requirements. Now, here’s a key point. All those specifications had to be met. The necessity was meeting the entire specification.  However, one of the prominent specifications, either explicit or implied was parsimony. Systems had to work but if they were unnecessarily complex that could make them very costly to make, maintain, and be less reliable. So, “Entities should not be multiplied without necessity”. Parsimony then is an essential component of the mindset and method of design so that things work well.

Now, let me turn to the use of parsimony in theology and metaphysics. I think the aforementioned understanding of parsimony is also an essential part of the mindset and method of doing them.  Metaphysics and theology both require speculations. That is the nature of metaphysics. So, the KISS method (“keep it simple, stupid”) should be taken seriously.  However, there is also a constant dialog going on.  Every step in a design (theological or metaphysical) constrains what can come next. So as the design process unfolds, every step along the way must try to anticipate the consequences for what will come later. If this is not taken into account, entities will have to be multiplied later to compensate for this lack of foresight. When that happens things can get out of hand quickly and create more opportunities for the system to become incomplete, incoherent, contrived, or inconsistent.  So, the challenge for these types of systems is finding one that works (more on this in a bit) without creating complexity beyond necessity. To do that one needs to think about the entire specification throughout the design process.

Where it is Misused
Parsimony is misused in metaphysics when it is used as an argument. There are several ways the concept of parsimony can become problematic. Metaphysicians and theologians try to make arguments for why their formulations are right. Fair enough. They offer exhibits like data, logic, consistency, coherence, explanatory power, and so on. However, if parsimony is used as an exhibit — an argument, that is problematic. It’s problematic because it can lead to a misunderstanding, be counterproductive, and/or be misleading.

The first way it can be misunderstood is when it is really an argument from simplicity. There is a major difference between “not multiplying entities beyond necessity” and an argument from simplicity.  Parsimony is neutral on whether or not an explanation will end up being simple or complex. It simply suggests that it is best to not go overboard with speculations when they are not necessary. However, if the argument-from-parsimony is really an argument from simplicity that has a presupposition embedded in it that fundamental reality is simple so it can or should be characterized in a simple way.

An example of this type of inclination can be found in physics where there can be a presupposition of simplicity such that major efforts and resources are committed to finding an equation that completely explains physical reality but can also fit on a tee shirt. Now, I don’t think searching for such an equation is problematic itself, but if there is a driving desire for such a simple solution, that can be counterproductive and prematurely cut off entertaining other more complex options. This could also apply to metaphysics.

However, the most abused form of parsimony-as-an-argument comes in from the very nature of metaphysics. Almost invariably metaphysics is systematic. Systematic metaphysics is a complex arena. There are many parts to it that are relational and often combinatorially so. 

What characterizes a system? It should be coherent, logically sound, consistent, complete, rigorous, and elegant(including parsimony in the first sense I mentioned). There is so much going on in these systems that parsimony-as-an-argument, if used, would have to apply to the whole system.  Since there are so many interrelational parts involved, how could parsimony possibly be asserted coherently?  At best it would be just a vague intuition and not definitive at all.

So, for those who are trying to evaluate a metaphysical system, an invocation of parsimony could be misleading.  An argument is supposed to contribute to the validity of an explanation or solution. But does parsimony really do that in systematic metaphysics?

A way to approach this question is to look at it pragmatically. To use an engineering phrase: “Does it work?” That depends on what “it works” means. To answer that we’d have to look at the domain of “it works”. Does it meet the entire “specified requirements?”  One way to think about this domain is to determine what questions are being asked. Metaphysics is an attempt to speculated beyond “the physics” which means explanations are sought that offer answers to certain questions. If parsimony-as-an-argument is invoked, almost invariably the domain is very restricted.  This can be misleading because as the system expands beyond that limited domain and tries to offer answers to the full gamut of questions, the so-called parsimony can evaporate with a series of ad hoc assertions, questionable brute facts, or odd contrivances in an attempt to make things work.  This is why seeking parsimony-as-an-argument for a system is ill-conceived and often misleading.

Let me offer a couple of examples where I think this issue can be the case. The problem of subjective experience or phenomenal consciousness has found a lot of interest among philosophers of mind and in social media. How do we explain subjective experience within present worldviews? Materialism (a.k.a. physicalism) seems to have a problem with this. I won’t go into this question in depth here but among the proposals getting traction that supposedly offer better answers than materialism are forms of panpsychism and idealism.  There are many varieties of these but in some of the prominent ones, the idea is to make experience fundamental.  If subjective experience doesn’t fit in with materialism, why not just make it fundamental? So, in these systems, experience is what might be called the ontological primitive upon which everything else is built.  Some forms of idealism have called this the “consciousness only” model. (Note: This is very different from the divine idealism I argue for on this website.)

So, what are the arguments for this approach?  Prominent among them is an argument-from-parsimony.  Supposedly it’s the simplest explanation that accounts for subjective experience.  Now, if the question of subjective experience is the complete domain of interest, parsimony-as-an-argument could carry some weight.  But is that really the total domain of questions? Hardly. First, when a simple primitive is posited as fundamental then how are the complexities we see accounted for? For example, in physics, the standard model has various types of particles (or excitations in quantum fields) and the four fundamental forces.  So, this physics model is complicated. To be consilient with this model, the experiential fundamental would have to be more than just a raw experience. There would have to be some relational dynamics also in play that mirrored things like mass, spin, charge, as well as the strong and weak nuclear forces, gravity, and electromagnetism or the fields associated with them. Suddenly, experience as a fundamental becomes much more complex with lots more going on than just a raw experience.   

Then for human beings, there is much more. In systematic metaphysics, all related issues need to be addressed. They can’t be ignored because inevitably these other issues will enter into the conversation. We see this in interviews, podcasts, and videos.  Questions are posed like “what does this say about the meaning of life?” or “does free-will fit in somehow?” or “what does this mean for morality?” Eventually, existential issues like meaning, free-will, purpose (teleology), morality, and so on, are raised because metaphysics isn’t taken as just some neutral puzzle-solving endeavor.

How would a so-called simple fundamental answer those questions?  Is there a meaning principle in experience? Is there a free will process in experience? An experiential purpose element? A value law?  And so on.  Again, suddenly a so-called parsimony begins to seem suspect. To make it work what we might see are odd contrivances, equivocation, obfuscation, and ad hoc postulates or brute facts. In other words, “entities will have to be multiplied” to make the system work.

Now, perhaps there are ways to make this “consciousness only” model work. Time will tell. My point is that parsimony-as-argument based on an extremely limited domain is ill-conceived for systems. For systematic metaphysics, parsimony-as-an-approach is a perfectly legitimate aim but as-an-argument it shouldn’t be given any weight.

Why this might matter?
Human beings are meaning-seeking creatures.  Without a sense of meaning all sorts of psychological problems arise.  To a large extent that meaning comes from a worldview — who and what we are and our place and relationship to reality. In every age, there are many worldviews in operation. They vary not only among individuals but also between cultures. Often they form a basis for how lives and societies are structured and operate. 

It appears we are in one of those periods in history where there is a growing trend to reject past worldviews and the metaphysical systems that support them. They just aren’t compelling to many people. Of course, this is nothing new. There have been periods of relative stability where certain worldviews were generally accepted for long periods of time.  However, as things change in culture and knowledge that can present challenges to a current metaphysical system or religious tradition.

As an example, polls have shown that the fastest growing group relating to religion are the “nones” — the unaffiliated. This is particularly true for younger people.  Whether or not this is problematic for someone depends on the individual.  I can speak from personal experience because I became unaffiliated over 30 years ago.  There can be a sense of loss but it can also be liberating. However, for me, it also created a feeling of being adrift religiously.  I remained a theist but wasn’t sure what that meant for me.  That situation was the impetus for me to work on the theology found on this website.

So, there is a growing number of those who do not feel the religious traditions compelling anymore but there may also be others who are outside the traditions and have an uncomfortable feeling about the worldview they presently feel aligned to.  These could be atheists, agnostics, or those who do not have a religious background.  If there is this metaphysical unrest then what is a person to do? Often this results in a search for something to address that unrest.  It may start with surveying long-standing metaphysical systems.  If those don’t seem right then it may broaden to new approaches.  As far as I’ve been able to ascertain, there haven’t been many new systematic metaphysical systems recently. I can think of a couple — process philosophy and integral theory (Ken Wilber), but there does seem to be more on the horizon coming from the philosophy of mind arena like those I mentioned earlier.

The question is, how can they be assessed and which ones seem compelling?  What criteria or reasons can be brought to bear?  Well, obviously this can vary greatly from person to person. For some, it may be primarily intuitional but for others, a more explicit, detailed, and rigorous approach is needed. If the latter is the case then arguments are important.

Now, since the religious traditions have become a disappointment to many, the last thing those searching for their metaphysical bearings would want is to entertain a new metaphysical system only to find out later that it had deep flaws concerning the most pressing existential issues I’ve mentioned. This is why I think it is important to be clear about what is being argued for in a metaphysical system.

Accordingly, I think too much illegitimate weight is put on parsimony-as-an-argument for metaphysical systems.  Claiming parsimony as a major argument for a particular system can be so misleading I don’t think it should be used at all.  Systems are far too complex, combinatorial, and interrelated to claim parsimony. Instead, the totality of arguments within a system that addresses all relevant issues should determine whether the formulation is compelling or not.