Theory, empirical data, appearances and illusion


Time and the metaphysical condition of illusion

What illusions do theories of perception have to explain?


Of all my research, this is the area of which I am least sure. It seems to me that much of the philosophy of science literature concerned with metaphysics (and not, e.g., epistemology) is about questions such as, e.g.,

(a) How necessary is realism about scientific entities for theory — e.g., must electrons be real for them to be useful for explanation?


(b) Is empirical evidence a sufficient or exhaustive means of evaluating competing scientific theories?

I think what I’m interested in here is related to these questions (as seen below) but it is not the same. Instead, my concern is with how one uses empirical data in evaluating scientific theories.

  • Unlike ‘a’, I am neutral in regards to the reality of entities posited by such theories.
  • Unlike ‘b’, empirical data is a means of evaluating two competing theories; it concerns cases of evaluation falling within empirical evidence. Although it does not require that empirical data is the only kind of evaluation (what I take to be the issue with ‘b’).

What I express here might be plausible, necessary, contingent, or impossible. In any case, I am expressing it from a position of unreflective — or barely reflective — intuition; what I say here seems prima facie plausible to me. In the context of this project, I think it is fair to start with this, and modify it as I go. But I cannot pretend that this is not a naïve point in my research.

In any case, I’ll press ahead.

My first thought about empirical data and scientific theory is this:

  • Correspondence of a scientific or empirical theory to empirical data is a good-making feature of that theory.  Empirical data is a way of evaluating competing scientific or empirical theories. If some empirical datum = ‘x in situation E’, then if: ET1 (a scientific or empirical theory that predicts or claims ‘x in situation E’) and ET2 (another scientific or empirical theory that does NOT predict or claim ‘x in situation E’, or even DENIES ‘x in situation E’), then ET1 is a better empirical or scientific theory than ET2.
    • Some theories cannot be compared this way. They both predict or claim ‘x in situation E’ and are both consistent with that empirical datum, or both do not predict or claim, or both even deny, the datum. As such, this empirical datum is not a way of evaluating these theories. Such a situation, I am given to understand, is described under the Dukem-Quinethesis (in Stanford 2009).
      • First, this neutrality regarding empirical data is not the situation I am interested in; I am concerned by situations where, prima facie at least, one theory predicts or accepts the datum, the other does not predict it and/or denies it.
      • Second, I am not sure that a point debated between two theories which is not distinguished by an empirical datum is, relative to that empirical datum, rightly thought of as a point debated by these theories as scientific or empirical theories. What would make them scientific or empirical theories is something else, some other way in which they are tested by empirical data. Leading to this:
        • If one were to have two theories which were both consistent with all of the same empirical data, then what distinguishes them, and thus what is only relevant to evaluating one over the other, does not fall within the domain of science or empiricism. It is, in my view, then a metaphysical issue.

    My worry about illusions(and hallucinations) is that any casual use of illusions and hallucinations to remove appearances allows one to neutralise the evaluative force of empirical data. In doing so, by removing the force of appearances, it turns claimed scientific or empirical disputes into metaphysical disputes.

    • By ‘casual’ I mean one claims, for whatever reason, that ‘x is an illusion’ and then leaves it at that, without explaining hownot why — such an illusion occurs.
    • For a scientific theory, casual positing of illusions and hallucinations from within one’s theory is a bad-making feature of that theory as a scientific or empirical theory.
      • But it’s grand as a metaphysical theory. Metaphysical theory is entitled to use whatever works to explain the world, so long, I think, as it is coherent.
        • If you want to claim that everyone everywhere is constantly in perceptual error, except on precisely the winter solstice, then if that is coherent, and explains the world better than alternatives, go for it. Just don’t pretend that your theory has not become a metaphysical theory.
      • By ‘from within one’s theory’ I mean that the illusions and hallucinations are not already there in one’s domain of enquiry. If the illusions and hallucinations are not from within one’s theory, they are ‘from outside one’s theory’. In that case,  they would be forced upon us with or without that scientific/empirical theory. In that case, they are not a bad-making feature of that theory.
        • Or, I should say, they are not a bad-making feature of only that theory. It may be that many competing theories all involve commitment to these illusions and hallucinations, and so cannot be evaluated by them in comparison to each other. But there may be another theory, or group of theories, which are not committed to these illusions and hallucinations. If so, regarding these illusions, the first group are negatively evaluated in comparison to the second group — again, as scientific and empirical theories (as metaphysical theories, there is no problem).
  • A central component of empirical data is what is apparent. I think this is an intuitive point, but as will be discussed it might be controversial for some. When something is empirical, when it is empirical data, it is constrained as follows (in my view; again, this may very well look like a very naive view).
    • Empirical data needs to happen in time. The observation is not of Platonic truths such as those of mathematics. Reason, or the rationality, is generally held to give us access to those, and reason has historically been considered an alternative to the empirical. (This is not to say that it is not itself a kind of perception — Godel, for one, thought that we perceive mathematical truths similar to how we perceive distant mountains (Yourgrau 2005))
    • Empirical data also has to involve appearances in some way. I would say that it is not something we only infer from appearances, but includes appearance themselves. How things seem is part of the empirical data. One could also include, and in practice one does, what it is plausible to infer from appearances.
    • Empirical data is public: a shared entity to which separate individuals have access.
      • I do not think this is necessary for a scientific or empirical data. Hume may be the only person alive, and the only person with access to data, but he may still be entitled to call it empirical data. However, considered in the context of its role in a scientific or empirical theory, there are other conditions of such a theory in the actual world: such a theory is a shared theory, with data which different individuals can show to each other. That is, the data, the empirical data, is public in actual world theories.
      • This raises the possibility of the following tension: What is apparent is part of empirical data. But empirical data is also public. Yet, one might object to this for the following reasons: (a) what is apparent is not public; it is particular or private to each individual or (b) assuming that what is apparent is public to assume to assume a disputed metaphysical position: naive or direct realism, perhaps.
        • In particular, this tension comes where what one is referring to in referring to appearances is to what some others may call ‘phenomenal’ or ‘qualia’. The what it is like of experience is apparent to one but is not public, so this thinking might go.
          • In response, one might say: qualia shows that some appearances are private. In that case, they are not empirical data. But those appearances that are public can be empirical data.
          • Alternatively, I suppose someone might claim they are public enough to be empirical data because each subject understands what other subjects mean by such qualia, e.g., the red-ness or blurriness, etc., although they do not have access to the specific case of the other subject’s qualia. Not only is there something it is like to see red, but lots of people know what it is like, and so it is something we can discuss publicly. But my thinking is that ‘public’ in this sense refers to be reports by subjects, not the qualia themselves (and so we have the sort of distinction made by, e.g., Dennett’s heterophenomenology).
        • But one might still object if one held that all appearances are private and not public. This is especially the case for those who hold sense-data theory. Sense-data are the bearers of properties that external things seem to bear, e.g., colours, shapes, and so on. Sense-data (like qualia) are private, not public, and so, by the definition suggested here, cannot be empirical data. But if they are not empirical data, what is?
          • I take it that such problems are problems — this is a tension for empiricists who hold to appearances being private (as, e.g., sense-data). I think sense-data theorists should offer an explanation for it. But still: if they deny that appearances play a role in empirical data, I think that this is also a problem. I leave it to advocates of such views to sort it out.
          • I suppose one way around it is to note that, by motivation of their introduction to theory, such entities as sense-data entail a public world which, in most cases, causes the sense-data; I’m thinking here of the sort of process from sun shine to sense-data one gets in writers such as Russell [reference pending, but check my 2010b for brief discussion concerning time-lag]. Then, in cases where they happen all on their own, these are illusions and/or hallucinations., and are not empirical data.
    • Appearances, and what we infer from them, play the evaluative role in scientific and empirical theory. If a scientific or empirical theory matches the appearances, this is good; if it does not, this is bad.
      • This — I take it — is what is meant by ‘saving the appearances’.
      • The ‘what we can infer’ shows one way out with illusions and hallucinations.
        • One rejects the appearances and does not save them because they are appearances in cases of illusions or hallucinations.
        • However, as discussed above, I consider doing this to be a bad move for a scientific or empirical theory.
        • One may be forced into that move for a scientific or empirical theory. But if your competitor is not forced into it, then they have the advantage.

Conclusion of this section

I’ll leave this here for now. As I said, this is primarily a laying out, with some basic justification, of my intuitions about empiricism, appearances, scientific theory and illusion. I expect to modify it from any comments I get, discussions, or publications.

The main conclusion I think is this:

1. Appearances, as components of empirical data, evaluate the claims of scientific and empirical theories.

2. If you dispense with appearances in your theory, then your theory is not a scientific or empirical theory.

3. If you casually assert illusions or hallucinations as an explanation of appearances, then you dispense with the appearances.

4. So, if you casually assert illusions or hallucinations as an explanation of appearances in your theory, then your theory is not a scientific or empirical theory.

‘4’ is a very strong claim. I am aware of that, but do not know what an alternative position to take about scientific/empirical theory and illusion/hallucination could be. In science/empiricism, appearance matters to ontological claims; in illusion/hallucination, appearance does not matter to ontological claims.

Still: perhaps we could remove appearances, remove how things seem, and try to re-define a notion of empiricism without it. Given the angle of my work here, I can see why this would be a desideratum of theorists who want to remain proposers of scientific theories but want to ignore appearances.

To my mind, this revisionary conception of empiricism is not ideal. I do not know how one can say that there is empirical evidence of some x if at some stage there is not an appearance of x or an appearance from which one might infer x. That is, although scientific (or other empirical) claims might go beyond the appearances and naive assertions about reality, I take it that, as claims that are scientific (or empirical), they are grounded and constrained by how things seem.

Even if experimental design involves unobservable events, even if one’s understanding of the resulting data is exhaustively contained within a language or theory with necessary and prior metaphysical commitments (as ‘theory-laden’ debates concern, e.g., ): if it is scientific or an empirical theory, and not a , I take it appearances are part of the evidence. They are part of how one confirms or falsifies the theory; they increase or decrease the probability of the theory being true (e.g., Williamson 2000).

But this is all by the wayside if it is only a naïve view, if this is only how it seems to me given my current understanding. If presented with sound or at least valid arguments, perhaps I can be persuaded away from this thinking.


2 thoughts on “Theory, empirical data, appearances and illusion

  1. Pingback: Illusion and the embedded/extended mind hypotheses « Time and Illusion

  2. Pingback: First steps: Time and the metaphysical condition of illusion | Time and Illusion

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