When choosing between competing metaphysical theories to determine which best explains the data, how can we first decide what qualifies as "the data"?

Question

To motivate this question, let’s consider some radically different metaphysical theories:

1. Theory 1: Physicalism, formalized through variations of the Standard Model and General Relativity, along with efforts to reconcile them, such as String Theory.
2. Theory 2: Bertrand Russell's five-minute hypothesis.
3. Theory 3: A version of Metaphysical Solipsism that posits time is an illusion, and only this mind exists in the present moment.

Suppose we want to compare these three theories in terms of how well they explain "the data." But what data are we talking about? Imagine an advocate of Theory 1 (Physicalism) claims that the relevant data includes billions of years of cosmic history leading up to the Big Bang. In response, a supporter of Theory 2 (the five-minute hypothesis) might counter, "Wait—how can you expect us to explain billions of years when the universe has only existed for five minutes? The only relevant data is what has occurred in the past five minutes, nothing more." To this, an advocate of Theory 3 (Metaphysical Solipsism) might interject, "Hold on! Why insist on explaining any past at all when time itself doesn’t exist? Time is an illusion; the only reality is my mind in this eternal present. Any perception of time passing is merely an illusion happening right now. Forget about billions of years or even five minutes."

This situation illustrates how presupposing billions of years of history as necessary data begs the question for the five-minute theorist, who believes the universe has only existed for a few minutes. Similarly, presupposing a past that requires explanation is question-begging for the metaphysical solipsist, who views time itself as illusory.

In the same way, assuming the existence of patterns, correlations, changes over time, or a vast universe out there populated with planets, stars, other minds, etc., is equally question-begging for the solipsist, who regards all such things as illusions experienced by this mind in the present.

For the solipsist, the only "data" that needs explaining is the content of their mind at this moment.

For the five-minute theorist, the "data" to be explained is whatever has transpired within the past five minutes.

For the physicalist, the "data" that needs to be explained includes all observable physical evidence in the universe around us.

In fact, we could even entertain other perspectives. For instance, a supernaturalist who believes in a natural-supernatural dualism and the possibility of mystical experiences might include a spiritual realm—one they claim to have directly experienced—as part of the "data" needing explanation, alongside ordinary physical experiences of everyday life.

So, if we aim to compare these theories to see which best explains "the data," how can we even define what "the data" is in the first place without presupposing one theory is correct, thereby arbitrarily shaping the data in favor of that particular theory?

Answer 1

None of those make any predictions about the world, so nothing in the world counts as data and nothing ever will.

Note that this means that none of them are theories or hypotheses in the scientific sense.

The Standard Model, Relativity, and String Theory are theories in the scientific sense. They make predictions. (Even String Theory - its problem is making novel predictions that aren't already made better by the Standard Model.) You can go out and measure them. The relevant data are the measurements that are relevant to their predictions.

Physicalism isn't physics. It's (charitably speaking) an a priori epistemic commitment to expect scientific methodology to be effective for investigating all aspects of reality. Less charitably, it's so under-defined that it isn't anything at all, as I argued here. Being (charitably) an a priori commitment, it is not a testable prediction and so there are not and never will be any relevant data.

Naturalism, not mentioned but related in that most physicalists are naturalists, is an a priori ontological commitment to conceive of everything as part of a single interlocking self-determining mechanism. Being an a priori commitment, it is not a testable prediction and so there are not and never will be any relevant data.

The five-minute hypothesis is a deliberately constructed parody of an a priori ontological commitment to conceive of everything as part of a 5-minute-old universe. Being an a priori commitment, it is not a testable prediction and so there are not and never will be any relevant data, which is the point that Russell is trying to get across.

Solipsism is a consequence of an a priori commitment to not have any a priori commitments except for the I-ness of the I-sense, the reasonableness of reason, and the self-referential commitment itself. The only relevant datum is the self-observation of the I-sense; all external data are now and always will be irrelevant.

Answer 2

I mostly come from a scientific rather than a philosophical perspective, but here goes.

Frame challenge: I feel like this question is backwards. One doesn't propose a theory and then ask, "What data could this apply to?" It's the other way around: You start with observations (data), then proposed a hypothesis to explain them.

This is hard to see, for example, with Russell's five-minute hypothesis. But only because his starting point is so broad. He is starting with all human experience. (And then proposing—for the sake of argument—the five-minute hypothesis as an idea to be disproven.)

Taking the Russell example further (or "When choosing between competing metaphysical theories"): Theories are made to explain. If some data can be explained by a hypothesis, it's relevant. Alternatively, if some data could disprove a hypothesis, it's relevant.

Answer 3

The data should be chosen based on the scope of phenomena you would like your theory to be consistent with.

If you don't care about consistency of a theory with anything beyond the content of your mind, then go ahead and limit the data to that.

If you would like your theory to be predictive of events more broadly, it is prudent to use other sources of data.

The data used to test the theory should at minimum consist of the very events the theory purports to predict.

If you would like the theory to be consistent with observations made by others over the millenia, it is best not to ignore that data either.

Answer 4

The data are superficially the same phenomena in each of the cases you mention. For example, the observed motion of planets about the Sun. Bertrand Russel has to account for why that should have started five minutes ago, and why logs of planetary motion created five minutes ago should include the positions of the planets reputedly at earlier times. While the solipsist can deny that planets exist, they still need to account for why the non existent planets appear in their mind in a particular way. The physicalist can account for the detailed movements of Mercury with a theory of curved spacetime. It is rather tricky for the solipsist to explain why the imaginary concept they know as Mercury behaves in the way it does.

Answer 5

From a science and engineering point of view:

If you want your theory to be compatible with "reality" , you use all data available, to the limit of available precision. If there are data points it doesn't fit, you need to be able to characterize those and explain whether they are erroneous data, systematic exceptions which have some pattern to them, or something else.

If the theory only works with a subset of that multivariate space, it may still be useful for that subset but is not a complete model of reality. Science advances by understanding the limits of its theories and refining them or replacing them as ways are found to make the theory match in more situations and to greater precision. Science never presumes to have the ultimate answer to complete precision, it is just an ongoing set of best available models.

If you are talking about some other kind of truth and reality, I am the wrong person to try to answer.

Answer 6

'The data' is merely the mass of applicable recorded measurements we have to hand in a given moment. 'The data' is comprised of bare facts: events as they have presented to our perception prior to any analysis or interpretation.

To invoke a different theory domain, consider that fossilized bones are facts. They perceptually exist: we can see them in person or in pictures; we can run tests on them; we can touch them or even taste them if we're in a weird mood. Fossilized bones are a set of data. How that data will be interpreted or organized is a different question:

• We can hold that the fossils are hundreds of millions of years old, formed by slow chemical processes on the remains of long-dead animals, and reflect the evolution of life over eons
• We can hold that the fossils are at most 6000 years old (per Young Creationism) and were either formed by unknown rapid geochemical processes or were included as part of creation
• We can hold that the fossils are entirely a concoction of the human mind, and thus reflect neither time nor an external world

We van make any theory we like, so long as that theory accounts for all events as they have presented to our perception.

Now obviously there are exclusion principles in play to remove non-pertinent events from a data set. But such principles are always functions of dispute and debate. If I merely say that fossils are the bones of animals from hundreds of millions of years ago, that's dismissible enough because there's no reasoning there; it's just a claim. But if I amass evidence (generate new observed events of various types concerning those fossils) and build arguments (weave these observed events together to create a coherent story-line about fossils), then any effort at dismissing my original statement must also cope with the amassed evidence and argumentation. Such can't simple be ignored, but must be accepted, co-opted, refuted, refocused, or reanalyzed. The observations of our senses must be embraced, considered, and ultimately put to rest in one way or another, so that whatever we come to believe contains all of our collected observations coherently.

In the long run, part of the process of determining which theory 'best fits' the data is arguing about which sets of observations seem to belong together. Generally we want to be as inclusive as possible — theories that account for more observed events are more useful and powerful — but we also don't want to stray outside the proper domain (e.g., if we're making a theory about bird flight we likely want to exclude observations of moose or camels). It's a terrain-mapping issue: if we want to know the extent of a hill, there will be differences of opinion on where we place the edges of the hill (should we do it according to height above sea level? transitions in rock composition? geometric inflection points?). 'The data' may shrink or expand at the periphery for what the main field of observations includes, but the bulk of the hill remains, and must be accounted for.

Answer 7

By definition, metaphysics is in a territory beyond data. "Physics" (aka science) is the realm of data and their interpretation. Metaphysics is more about whether we ought to gather data at all and why, whether it makes any sense to try and understand the universe rationally, what basic presuppositions do we need to assume in order to build any form of systematic knowledge, etc. It's not about how the world is or behaves factually, but about its meaning for us. There's no way to discriminate between metaphysical theories based on observations; they are a matter of belief, or use.

This is one of the meanings of Popper's falsifiability criterion: Is scientific any theory that makes testable (empirical) predictions, ie a theory that accepts SOME KIND OF DATA as its judge, that accepts the verdict of facts. If your examples (physicalism, solipsism, etc.) were indeed testable with ANY fact, then they would be scientific theories as per Popper's criterion. But they don't seem to be testable with data, by your own account. Therefore, they belong to another realm of human enquiry than science. In this particular case, they belong to metaphysics, as your title correctly mentions.

Answer 8

Those are just three different types of epistemology,and Philosophy knows many more, see e.g. https://en.m.wikipedia.org/wiki/Epistemology

Different people make different choices of epistemology, though usually not consciouly. This can be based in their purposes in life, or because they have been taught that way. It's very individual, and probably more of a psychological than philosophical question.

Any two people do not necessarily agree, but schools typically steer students towards some epistemology such that people from similar schools have very similar epistemology, and can best cooperate in achieving any joint goals without debating epistemology first.

People are also subject to various other organizations attempting to control their beliefs. Cults try to ensure members only expose themselves to cult beliefs. Social media tries to expose users to such data that keeps users hooked. Journalistic mediuma try to strike a balance between engagement and relevance.

Philosophy does not necessarily judge any approach, but a goal of philosophy is to gain much true beliefs and little wrong beliefs. This is not necessarily the goal of all people or organizations.

The question on how to choose one epistemology is considered in meta-epistemology: https://plato.stanford.edu/entries/metaepistemology/ (And it's not straightforward)

how can we even define what "the data" is in the first place without presupposing one theory is correct, thereby arbitrarily shaping the data in favor of that particular theory?

There are different ways to identify and avoid biases. Those are to varies and context dependend to describe in an answer here. Epistemology helps to define what the data is "first", instead of deciding for a theory first.

Answer 9

The data is in our present. It is memories. It is writings. It is photographs. And so on.

All these are in the present.

What the theories have to explain is why all these data are mostly consistent.

I remember (mostly) the same yesterday as my friend. What is stored in one person's email Inbox matches what is stored in another person's Sent Mail.

If your hypothesis is that the past actually happened, all this is easy to explain. In fact, it is the very few exceptions that make problems.

If your hypothesis is that the memories/writings/photos etc came spontaneously into existence five minutes ago, it becomes very hard to explain all this consistency.

Answer 10

You ask:

When choosing between competing metaphysical theories to determine which best explains the data, how can we first decide what qualifies as "the data"?

Oh, this is no simple ask. Your question is a metaphilosophical question because it asks us to choose among competing metaphysical and physical theories as well as deciding on a philosophical methodology. This question is only one degree removed from "What is philosophy, and how should it be done?" Ultimately, your question exceeds the bounds of Q&A if you are looking for a complete answer. I suggest that you get a copy and read An Introduction to Metaphilosophy (GB) by Overgaard et al. If you want a thorough answer, you have to consider the entire breadth and depth of philosophical discourse, including whether you should even consider having theories at all, which as Richard Rorty considered, is a representationalist approach to philosophy.

In the spirit of neo-pragmatism, you might want to consider advice by Richard Rorty, following in the footsteps of LW, Quine, and Sellars, who wrote a book called Philosophy and the Mirror of Nature in which he questions the very nature of what you consider: metaphysical theory building. Rorty does this by questioning how to go about understanding knowledge and truth, parting company with the more scientific approaches; this includes the formal, natural, and social sciences, which are always striving to ensure that truthful claims cohere with themselves and correspond to the external world. For Rorty, he takes a more humanitarian approach by furthering the argument that language is but a tool, and a lot of philosophical dickering are pseudoproblems, a critique of philosophy that goes back a long way and was famously conducted by Carnap.

But before you can decide among philosophical approaches and metaphysical theories, you might want to simply use your intuitions to determine what you prefer since belief systems, what Dilthey terms Weltanschauung, come in a few flavors. One approach is the religion and theology which emphasize experiential data of the divine, another approach is humantarianism one which emphasizes the primacy of the human spirit and dignity and tends to be favored by Continental thinkers, and the last is analytic philosophy which champions science and the naturalized epistemology (SEP), which emphasizes building analytic models of language and nature. Philosophy has these three broad approaches among its offerings that you must consider and choose from.

If you can figure out among the three approaches to metaphysical theory for which you have a preference, then you can get busy devoting yourself to the appropriate tradition. Of course, this self-actualizing approach to considering metaphilosophy is part of the way of conceiving experiential data called existentialism. Thus, if you have any trouble deciding which among the three Western approaches: theology, Continental, and analytic philosophy (there are non-Western approaches my ignorance of fills countless volumes that I simply am too ignorant to speak to), you have taken the first step to figuring out how to deal with your experiential data in a theoretical language that existentialists like Camus (apologies to Camus), Sartre, and Heidegger might help you with.