As frequent readers may know one of my many projects is to try and find a way to evaluate philosophical theories based on their content (instead of the arguments for them). Here then is my first proposal, partly unfinished, as to how that evaluation could be done. It comes from understanding the point of philosophical theories as the explanation of certain features of the world either not easily measurable or normative, and thus not captured by science. What then makes an explanation successful? I think the answer is actually very simple (and its very simplicity is why it proved so elusive); a good explanation answers all questions.
Of course what questions are acceptable to ask and what counts as an answer are aspects of this proposal about explanation that need to be spelled out in complete precision, or relying on this standard will prove less objective than hoped, as people will disagree about whether a theory has really answered all the question.
Let me begin then by outlining the three ways in which a question may be answered by a theory:
a) The question is directly answered by the content of the theory, either because the theory directly makes a claim about it, or the theory makes a claim about it because it follows from the operation of certain theoretical entities. However, a qualification must be placed on such answers, it must not be the case that the theory can equally well explain the opposite as well (the content requirement, thus ruling out “magic” as being the best possible explanation). For example, a psychological theory might make claims about the internal state of Bob, and from that internal state answer the question “why does Bob want a hamburger?” by appeal to that internal state. However this answer would not count if the theory could equally well answer the question “why does Bob not want a hamburger” by appeal to the same internal state. Of course things can get tricky in scientific theories when separating observations that give us the information necessary to start explaining things with our theory and observations that we can reasonably expect the theory to say something about. But that doesn’t need to concern us too much when dealing with philosophy, as generally philosophical theories are less concerned with explaining specific events.
b) The question is answered by appeal to other theories (by saying that a particular fact or a particular mechanism is the domain of some other theory). Theories appealed to in this way may not actually have the answers to these questions yet, but such answers fail to count as answers if the theory appealed to doesn’t provide the right answer (if it denies that the fact is true or the mechanism exists). For example, an evolutionary theory may appeal to molecular biology in order to explain how traits are inherited (to answer the question “how are traits passed from one generation to the next?”). However this would not count as an answer if molecular biology failed to provide any mechanism by which traits could be inherited. It is reasonable to expect every philosophical theory to answer at least some questions in this way, if it didn’t that would imply that it was self-contained, which in turn would imply that it wasn’t about the world, since the world is described successfully, at least in part, by other theories.
c) The question is revealed as nonsensical or stemming from a different understanding of the concepts involved. Note that this is different than asking a question that is properly answered with a denial, such as “why is the sky green?”. Usually such nonsensical questions occur because we are demanding a kind of explanation that is inappropriate for the domain we are applying it to. “What is the purpose of the sun?” is one example of such a nonsensical question, since the sun wasn’t designed. Now we might say that the sun has no purpose, as an attempt at an answer, but what is really going on is that we simply are unable to apply the methods by which we would normally get an answer, namely by looking at the factors that guided the design of the sun, but there are no factors, and thus no way to get an answer using those methods. Similarly “what is the cause of the big bang?” is a non-question under some theories about it, coupled with a scientific understanding of causation, as causation requires us to find an event earlier in time that leads to that later event under natural law. But obviously it is impossible to find such an event before the beginning of time and outside of natural law. And so at best we can say that there is no cause. Such answers are, however, very rare, and I wouldn’t expect to encounter them often while evaluating a philosophical theory.
And for complete clarity it is also necessary to spell out what questions we can ask of the explanation. Because obviously it is wrong to say that fluid dynamics is a poor explanation of the way liquids work because it cannot answer questions about the nature of truth. Here I must be less precise. Let us simply agree that each theory has some specific intended object that it intends to explain (fluids, meaning, mind, ethics, …). Given that two questions naturally arise: “when is that thing present?”, and “what rules govern it?”. But admittedly these questions are a bit vague. And usually for any topic that a theory is intended to address there are a number of traditional questions about the topic, and it is reasonable to expect the explanation to answer them as well. In addition to these questions there are more, unique to each individual theory, in the form of “why is that the case?” about specific aspects of the theory. In the case of fluid dynamics we might ask, for example, “why does law X govern the fluid?”, which could be answered as b) above, by appealing to the micro-physics of the fluid. And of course we are free to ask questions about the answers given to other questions, until our questions cannot be answered, or are answered by appealing to other theories (response b) or are revealed as nonsensical (response c).
Given that I have spelled out, somewhat vaguely, what the ability to answer all the questions posed to a theory entails allow me to lay out a few reasons to think that this a promising way of evaluating philosophical theories. The first is that at a certain level scientific and philosophical theories are both theories about the world. Thus whatever method we endorse for evaluating philosophical theories should also apply to scientific theories, restricted to measurable phenomena. And indeed this way of evaluating theories, so restricted, becomes falsification by experiment. You see one kind of questions scientific theories are supposed to answer is “why did X occur”, where X is some specific event. Thus a successful scientific theory is one that explains all the observable phenomena. However if some phenomena is observed that the theory fails to predict, or predicts incorrectly, then the theory is falsified, revealed to be an incomplete explanation, and this is the core of the scientific method. And in our terminology falsification is simply the discovery of specific questions, “why did Z occur?”, that the theory can’t answer. So the scientific method is indeed revealed to be a special application of the general method outlined here.
A second reason to like this approach to evaluating philosophical theories is that it admits of degrees of wrongness. An explanation can fail by leaving some questions unanswered and still be a better theory than its competitors that leave more questions unanswered. And, hand in hand with this, is the fact that which questions it is unable to answer reveal exactly where the theory is in need of improvement or elaboration. Again this can be seen as a reflection of the scientific method, where the phenomena that are wrongly predicted reveal the domains that the theory fails to capture. In any case this is certainly better than trying to refute a philosophical theory by showing that it contradicts itself or some other premises, because doing that reveals nothing about where the problem lies; it is even possible for the problem to lie in the way that the contradiction was derived.
The third reason to believe that this may be a promising way of evaluating philosophical theories is because it rejects as faulty some philosophical theories that I feel fairly confident are lacking. But of course this may very well motivate some to reject my account of what counts as a good explanation, if they like those explanations more than they like this theory about evaluating explanations. Oh well. Let me describe three theories it rejects. The first is dualism as an explanation for the mind. Dualism can’t answer quite a few questions, even in principle, about the mind, starting with: “why do minded systems have minds?”, “how does the non-physical mind generate experience?”, and so on. Of course the fact that dualism can’t answer many such questions is no surprise, because the theory is motivated mostly by a belief that the mind can’t be material, and not by a convincing dualist theory about the mind. A second philosophical theory revealed as lacking is the causal theory of names. The causal theory of names is an attempt to answer the question “why does a name refer to the individual that it does?” in the context of theories including rigid designation by positing that users of the name can trace back their use of that name by some causal chain to an original naming event. But that raises the question, unanswerable by the theory, “why does that causal chain affect what the name refers to?” (revealing that the theory has not actually answered the original question, which was really meant to uncover how reference works in the case of proper names). Again, perhaps not too surprising since rigid designators and the causal theory of names were motivated primarily in response to perceived problems with definite descriptions, and not as part of a theory about reference that was independently compelling. And, finally, we come to god in general invoked as an explanation. God can’t serve as a successful explanation because it fails to answer questions about why god acts as he does. Of course partial explanations such as “god is good” answer general questions about god’s behavior, but not specific ones (why did god do X instead of Y), because they can equally well explain why god did Y if he had done that instead of X (the content requirement for type a) answers). (You might still consistently claim, if you subscribe to this method of evaluating philosophical theories, that god is good theology, just not good philosophy.)
Naturally since this is a philosophical theory about how to evaluate philosophical theories we should be able to evaluate it by its own standards. Most questions naturally posed by this theory have obvious answers, I think, although given that this method works a lot like falsification there is always the chance that someone will come up with a pressing question about explanation I haven’t anticipated that it fails to answer. Let me just address then the biggest question: why should we expect this method to yield true philosophical theories? That is a question I think has to be answered by epistemology, but let me sketch you an answer instead of leaving you completely in the dark. Obviously epistemology justifies the scientific method (if it didn’t it wouldn’t have an answer to the question “why is the scientific method so successful?”). And for the same reasons that it justifies the scientific method I expect it to justify this method, because false theories are eventually weeded out by their inability to provide answers, or by their providing the wrong answers (something that is especially likely to happen in the way they interface with other theories).