Review of Stewart Goetz and Charles Taliaferro's Naturalism
Causal Closure Unjustifiable, Basic to Naturalism
August 4, 2008
We recently read your review of our book entitled Naturalism and appreciate your thoughtful comments about it. Of course, we see things quite differently than you do. We would like to focus on one primary issue that we believe separates you (and other naturalists) from us. It is the matter of methodological commitment.
You state that it is “unfortunate that the methodological and epistemic commitments of naturalism, as contrasted with those of anti-naturalism, don’t get more attention in this book, since it’s these commitments that largely determine where these very different worldviews end up.” We would like to point out, however, that Chapter 2 is entirely devoted to the naturalist’s methodological commitment to the causal closure of the physical world. This commitment drives the naturalist’s world view and leads naturalists to question and deny the reality of how things appear to ordinary human beings. You ask, “Why suppose that the apparent distinctness of the mental and physical necessarily reveals anything fundamental about their true nature?” Methodologically, this gets things backwards. Our question is this: Why suppose that the apparent distinction of the mental and physical does not reveal the true nature of things? Why not stick with “commonsensical appearances as guides to reality" unless we have a reason to doubt those appearances? As a methodological point, naturalists usually respond that we cannot stick with commonsensical appearances as guides to reality because of the methodological commitment to causal closure. In other words, naturalists do give a reason for not sticking with commonsensical appearances. What we have done is examine that argument and found it wanting. Hence, what we hoped naturalists like you would do is show us where our examination of the argument from causal closure goes wrong. This is precisely what you don’t do in your review. Unless you can explain to us where our critique of the argument from causal closure goes wrong, we simply cannot find any reason to think that a person cannot embrace both science and the commonsensical appearances. Again, it is naturalists who say that the two cannot be simultaneously embraced and they invoke the causal closure argument to justify their assertion. We disagree, and have explained why we disagree.
Thus, as we see things, the causal closure argument is the pivotal point in the dispute between naturalists and non-naturalists. Until our response to it is addressed, there isn’t much hope for progress in the debate. Hence, when you write that our argument for causal openness in the brain “assumes that reasons and purposeful behavior can’t possibly be materially instantiated, that they can’t find a sufficient substrate in neural mechanisms," we are led to respond that the burden is on you to give us a reason why we must think that they have to be materially instantiated or realized. Again, naturalists give an argument—the argument from causal closure, to which we have responded. The burden is not on us at the outset to explain why reasons and purposeful behavior cannot be materially instantiated. The burden is on naturalists to explain why they have to be materially instantiated, if they are to be taken as real. If the argument from causal closure doesn’t work, and we have argued that it doesn’t, then we await some other reason from members of your camp that would explain to us why reasons and purposeful behavior, if they are real, must be materially instantiated.
You quote Owen Flanagan’s claim that causal closure is a justifiable regulative assumption in the mind sciences. We are very careful in pointing out the distinction between assuming casual closure in the context of scientific work and assuming causal closure universally. What we need to have from the naturalist is not a claim that causal closure is a justifiable regulative assumption in the context of scientific work (we agree with this), but an explanation for why any scientist who makes this regulative assumption must go on to assume universal causal closure. Once again, you provide no such explanation in your review. Instead, what you do is claim that assertion of causal interaction between a soul and mind has not been productive “because no researchable mechanism of their interaction has ever been produced.” Our point is that success or failure in providing such a mechanism is neither here nor there when it comes to the scientific enterprise. Scientists can do their science without having to worry the least bit about whether or not the dualist can provide an explanation of how souls causally interact with bodies. What the dualist needs to do vis-à-vis science is make clear that the existence and causal activity of souls poses no problems to the practice of science. Those who claim that the existence of and causal activity of the soul does prove problematic for science typically justify their claim with the argument from causal closure. Hence, we hope that naturalists who read the book will point out to us where our critique of the causal closure argument goes wrong.
Several times, you make mention of the problem of causal interaction. You say that “The perennial difficulty with dualism . . . is that no transparent explanations seem forthcoming about such interaction.” As we explained on p. 42, footnote 1, Kim (and if Kim isn’t a naturalist, who is?) believes that causation is basically a generative or productive relation. We concur with Kim. So what ANY entity must have in order to be a causal agent is the power or capacity to generate or produce an effect in another entity. There is simply no reason to think that only material objects can have such a power. So what the dualist asks is, "What is the reason for believing that souls cannot have such a power and exercise it?." The standard naturalist answer is the argument from causal closure. Hence, one again, the explanation for why we devote Chapter 2 to that argument.
Finally, you say that “for a naturalist the best (and perhaps only) reason to believe in dualism, mental causation and libertarian free will would be if we had a clear, evidence-based picture (or even a plausible preliminary sketch) of the causal relations between soul and body.” We shall make no attempt to deny what you say here. For you, this is presumably true. For us, we start with our first-person experience of the world and work from there. What we look for is a reason from the naturalist to doubt the integrity of that first-person experience. So far, we have not been convinced by the naturalist’s argument from causal closure. Because we believe that argument fails, we cannot help but continue to trust our first-person experience as evidence. And we cannot help but trust that evidence while at the same time cheering on science as it seeks to do its work in curing diseases and providing for a better quality of life.
With gratitude and warmest wishes,
Stewart and Charles
Motivating Naturalism: Wanting Objectivity and Transparency
The desire for objectivity and explanatory transparency motivates naturalism and militates against dualism and supernaturalism.
August 21, 2008
Dear Stewart and Charles,
Many thanks for your gracious response to my review of your book. Perhaps we can advance the debate in this exchange. I’ll argue that the assumption of causal closure, the idea that “a scientific examination of bodily action leaves no explanatory room for anything non-physical” (p. 28), is methodologically sound. It’s a defeasible assumption, not dogmatic. It's motivated by basic epistemic norms of objectivity and explanatory transparency that naturalists generally respect more than non-naturalists. Non-naturalists, I suggest, need to justify their epistemic laxity in appealing to mysterious dualistic mental causation. But first a bit about your argument against causal closure.
The argument against causal closure. You say in your book that the price for assuming causal closure is “absurdly high” (30) because it rules out any role for teleological purposes, consciousness, and libertarian (contra-causal) free will in explaining behavior. On your account these are ruled out by causal closure because they are mental phenomena in the sense of being categorically non-physical (immaterial). But there are viable accounts of purposes, beliefs, reasons and other causally effective mental states that don’t invoke anything immaterial or contra-causal (see for example my review of Nancey Murphy and Warren Brown who are Christian physicalists). Further, it’s possible that consciousness in the sense of qualitative, phenomenal experience (qualia) might be epiphenomenal. So for the naturalist who assumes causal closure, mental states, understood for instance as physically instantiated information-bearing representational states, can play a role in explaining behavior even if it turns out that qualia are epiphenomenal (the jury is very much out on epiphenomenalism). Thus the assumption of causal closure leaves many of our intuitions about mental causation intact, while providing a productive framework for research into the mind. So the price for assuming it is reasonable, unless, of course, we insist that all folk metaphysical preconceptions about mind and behavior (what you call the “natural” view of ourselves) must be confirmed by philo-scientific investigation. Further reasons for accepting causal closure are set forth below.
Objectivity. When I said that I had hoped to see in your book more discussion of methodological and epistemic commitments, I was referring to differing stances on basic epistemic norms which end up driving our very different worldviews. For instance, we have conflicting opinions on the reliability of what you call elsewhere the “first person data” of how things subjectively seem to us in experience. You raise this issue in your response above: “Why suppose that the apparent distinction of the mental and physical does not reveal the true nature of things? Why not stick with ‘commonsensical appearances as guides to reality’, unless we have a reason to doubt those appearances?”
As I think you’d agree, in deciding what’s objectively the case about the world we want to make sure that we filter out possibly distorting subjective perceptions and hopes about what’s the case, otherwise we might end up deceived. The reason naturalists think we shouldn’t stick with commonsensical appearances as guides to reality is not, as you say in your response, the assumption of causal closure, but that such appearances are notoriously prone to bias by wishful thinking and perceptual illusions. In particular, the subjective feeling that we possess a unitary non-physical soul might be a “user illusion” generated by the brain, reinforced both by our desire for immortality and centuries of dualistic religious and pre-scientific teachings about the nature of persons. That millions (billions?) of people feel and believe they have souls isn’t good evidence for the soul’s existence, just as the fact that millions believe in paranormal powers and astrological influences isn’t good evidence for those phenomena. To know that the soul objectively exists, we would need public, observational, intersubjective evidence, e.g., weighing a body just after death to see if it’s slightly lighter due to the soul’s departure (the fanciful basis for the film title “21 Grams”). Thus far there is no such evidence, indeed there’s no observational specification for the soul that could guide the search for it.
Naturalists, by sticking with science in the pursuit of objectivity, are simply being more vigilant about insulating their beliefs from the influence of wishful thinking and other cognitive distortions than non-naturalists like yourselves, who admit non-scientific evidence as good grounds for belief. Naturalists want very much not to be deceived about the world, so we don’t (or shouldn’t) have a stake in any particular ontology; for instance we shouldn’t dogmatically insist that only categorically material things exist. Non-naturalists like yourselves, however, are committed to a particular ontology, one which includes supernatural God, the soul, and uncaused choices. This tends to bias theistic claims about what's real. I discuss this and other cognitional differences between naturalists and non-naturalists in more detail in a review of theologian John F. Haught's book God and the New Atheism and in some commentary on Austin Dacey's The Secular Conscience.
Explanatory transparency. Another epistemic value of central importance to naturalists, but less to anti-naturalists it seems, is explanatory transparency. As I pointed out in my review, you provide no account of how the soul accomplishes its work in guiding behavior via its influence on the brain. Its modes of operation are a complete mystery, yet you give it a pivotal role in explaining behavior. This is to posit an unexplained explainer whose function is to fill an explanatory gap, in this case the absence of a fully worked out naturalistic theory of intention and action. For the naturalist wanting explanatory transparency such a posit adds nothing to our understanding; it simply begs a whole set of questions about the nature of the soul and how its non-physical, supernaturally free mental powers have physical effects. For you, this shortcoming of the soul hypothesis doesn’t count against it, whereas for naturalists it’s a complete disqualification. Faced with an explanatory gap, we cheerfully admit our ignorance: we don’t yet have a complete, transparent naturalistic understanding of mind and behavior. By contrast, you are happy to insert the explanatorily opaque soul and its mysterious free will.
The epistemic rationale for causal closure. There are thus two big strikes against the soul from the naturalist’s perspective: the failure to respect the basic epistemic norms of intersubjective evidence (in service to maximizing objectivity) and transparent explanation (in service to knowing how things work). These norms help motivate the methodological assumption of causal closure in the philosophy of mind. The reason that the immaterial powers of the soul, or any other categorically non-physical entity, are justifiably ignored when explaining mind and behavior is that there is no good evidence for the soul’s existence (see Objectivity above) and no explanation of how its immaterial powers influence the body (see Explanatory transparency above). The assumption of causal closure is simply a methodologically conservative and efficient stance in the absence of any evidence for, or explanatory advantage of hypothesizing a categorically immaterial realm or entity, and a fortiori any supernatural realm or entity. Were there any evidence or explanatory advantage, the scientist would seize upon it instantly, but there isn’t. So she doesn’t waste time on unobservable and unspecifiable non-physical/physical interactions, which is to say she operates under the defeasible assumption of causal closure. Defeasible, because we can’t rule out the existence of the mental as a categorically separate domain; indeed a few scientists and philosophers still hold out hope for it (see note 3). The assumption of causal closure in the philosophy of mind therefore isn’t dogmatic, but epistemically responsible and methodologically sound, given the goals of objectivity and transparency.
Motivating naturalism. You say “What we need to have from the naturalist is not a claim that causal closure is a justifiable regulative assumption in the context of scientific work (we agree with this), but an explanation for why any scientist who makes this regulative assumption must go on to assume universal causal closure.” By universal causal closure you mean “that the relevant brain (neural) states can only be causally produced by events of other physical entities and not instead by mental events of immaterial souls alone when they choose and intend (plan) to act for purposes” (35, original emphasis). No one, of course, must go on to assume this, but if you want reliable beliefs about what’s real and transparent explanations of phenomena, then it's rational to operate on this defeasible assumption, as opposed to believing in the existence of categorically immaterial and/or supernatural entities (God and the soul) for which there is currently no intersubjective evidence and which provide no explanatory gain.
Anyone wanting an objective view of things must filter out her preconceptions, wishes and cognitive illusions. Science does this best by far, and if we stick with it as our epistemology, science necessarily unifies our view of what exists into a single, natural realm, what we call nature (a realm that might, naturalists admit, possibly contain categorically non-physical entities according to some specification, even though there’s currently no good evidence for this). Anyone wanting transparent explanations won’t abide unexplained explainers, especially those that patently speak to her fondest hopes, such as God, the soul and libertarian free will. The upshot is that the desire for objectivity and transparency motivates naturalism and militates against dualism and supernaturalism.
Now, if you don’t primarily want objectivity and transparency, but are more interested in defending a preconceived ontology, then by all means open yourself up to non-scientific ways of knowing  – put stock in subjective appearances, intuitions and revelations, and posit whatever immaterial and supernatural entities and forces you like. After all, the epistemic standards that motivate causal closure as a defeasible assumption are no longer controlling, in which case anything is possible: gods, souls, angels, demons, paranormal powers - whatever unchecked intuition and revelation can dream up.
You say on p. 37 that
…the actualization of a microparticles’s capacity by a mental event on an occasion when a person chooses to act for a reason is not excluded by anything that is discovered in a scientific study of that capacity. And it is precisely on occasions like those involving the movements of our fingers and arms while typing that the neuroscientist will reasonably believe that the micro-physical neural impulses that led to those finger movements must ultimately have originated with the mental causal activity of a soul that was choosing to act for a purpose.
The naturalist agrees that science can’t categorically exclude immaterial God, souls, free will and mental causes, that is, it can’t categorically rule out their existence, but disagrees that there are scientific, empirical, intersubjective grounds for reasonably believing that they exist. Any neuroscientist or lay person who believes they exist does so on the basis of non-scientific, non-empirical, subjective claims to knowledge, claims that are unreliable routes to objectivity and that do little or nothing to explain the workings of the world. It seems to me that for these reasons it’s difficult to defend dualistic, supernatural theism as an objective and explanatory worldview. Of course you won’t agree with this assessment, so I welcome your thoughts on why theism should be considered objective and explanatory, or why there might be other good reasons to embrace it that naturalists have overlooked.
With all best wishes,
 In his book Being No One, Thomas Metzinger argues that our sense of being a unitary self is a representational construction of the brain that makes us adaptively egoistic in our dealings with the world.
Begging the Question of Evidence
September 15, 2008
Many thanks for your response letter of August 21, 2008. With the hope that we are making some progress in trying to understand each other’s positions, we offer the following thoughts about what you say in your August 21 letter.
In response to our critique of and position on the causal closure argument, you state that “there are viable accounts of purposes, beliefs, reasons and other causally effective mental states that don’t invoke anything immaterial or contra-causal. . . . So for the naturalist who assumes causal closure, mental states, understood for instance as physically instantiated information-bearing representational states, can play a role in explaining behavior even if it turns out that qualia are epiphenomenal . . . Thus the assumption of causal closure leaves many of our intuitions about mental causation intact, while providing a productive framework for research into the mind.”
We will not question your assertion that the assumption of causal closure leaves intact some intuitions about the mind, e.g., that qualia are real (which, by the way, seems to us to be an implicit acceptance of first-person data). However, we are confident that naturalist accounts of purposeful explanation supplant purposeful explanation with causal explanation. In short, such accounts eliminate teleological explanation.
Moreover, we never claimed that the naturalist could not employ the causal closure principle and try to retain certain elements of our intuitions about the mind. The question at issue is whether retaining a robust conception of the mind as a soul that makes libertarian choices for purposes in some way or other undermines the framework and practice of science. What naturalists argue is that retaining this robust conception of the mind does undermine science because of the causal closure principle. Again, we are looking for an explanation of where our critique of the causal closure principle goes wrong.
You proceed to assert the following: “[I]n deciding what’s objectively the case about the world we want to make sure that we filter out possibly distorting subjective perceptions and hopes about what’s the case, otherwise we might end up deceived. The reason naturalists think we shouldn’t stick with commonsensical appearances as guides to reality is not . . . the assumption of causal closure, but that such appearances are notoriously prone to bias by wishful thinking and perceptual idiosyncrasies. . . . That millions (billions?) of people feel and believe they have souls isn’t good evidence for the soul’s existence, just as the fact that millions believe in paranormal powers and astrological influences isn’t good evidence for those phenomena. To know that the soul objectively exists, we would need public, observational, intersubjective evidence . . . .”
Here (and at other points in your response), it seems to us that you have fundamentally begged the question against us. The issue is what counts as evidence, and you will only allow “scientific, empirical, intersubjective grounds” to count. You will only allow these grounds for evidence because you are a naturalist. We are not. Hence, what we need from naturalists is an argument for why naturalism is true. Again, the standard argument is the argument from causal closure to which we have authored our response in our book. At this point, you say “the reason naturalists think that we shouldn’t stick with commonsensical appearances as guides to reality is not the assumption of causal closure, but that such appearances are notoriously prone to bias by wishful thinking.”
Commonsensical appearances, such as that we think, hope, believe, and experience pain and pleasure, are not a product of bias and wishful thinking. The claim that they are is simply outlandish. Similarly, the commonsensical appearances that we are souls that make libertarian choices for purposes are not the product of bias or wishful thinking. As we see things, our debate with you (the naturalist) is not helped by such charges. After all, we could simply turn the tables and assert that your rejection of the soul, libertarian free will, ultimate and irreducible teleological explanation, and God are the product of bias and wishful thinking (assuming the naturalist admits the reality of thinking and, thereby, the possibility of bias). In his book, The Last Word, the well-known naturalist Thomas Nagel is honest about his bias and wishful thinking: “I want atheism to be true and am made uneasy by the fact that some of the most intelligent and well-informed people I know are religious believers. It isn’t just that I don’t believe in God and, naturally, hope that I’m right in my belief. It’s that I hope there is no God! I don’t want there to be a God; I don’t want the universe to be like that.” Fair enough. But if we are going to try to reason with each other about these matters, shouldn’t we leave our hopes and fears out of it? That is what we are trying to do, and as best as we have been able to determine the argument from causal closure plays the pivotal role in the naturalist’s argument against the commonsensical view and for naturalism. That is why we keep returning to it and asking for an explanation of where our critique of the argument from causal closure is mistaken.
At different points in your response letter, you suggest that we posit the existence of the soul, libertarian free will, etc. In discussing our position about the soul, you write “This is to posit an unexplained explainer whose function is to fill an explanatory gap.” We respectfully beg to differ. We never said that we posit the existence of the soul to fill an explanatory gap. Rather, we argued that there must be an explanatory gap in the physical world, given the existence of the soul and its choices to act. We are first convinced that the soul exists and makes libertarian choices for purposes and then go on to explain to our readers that the soul’s existence and causal activity implies that there must be a gap in the physical explanatory story. We are not first convinced that there is a gap and then posit the soul with its explanatory power to fill that gap. At this juncture, you might point out that our response assumes that first-person appearances are reliable. Well, as we just pointed out, we see no reason to question them, unless one is already a naturalist. But all we ask of you is this: assume for the sake of argument that a soul with its explanatory power exists. Is there any reason to think that there cannot be a gap in the physical world into which this soul might insert its causal influence? Naturalists regularly respond that there cannot be such a gap because of the argument from causal closure. Need we say more at this point?
You, however, raise another issue: dualists cannot explain “how its [the soul’s] immaterial powers influence the body.” It is not clear to us what constitutes an explanation for you. As we explained in our book, a common and reasonable way of understanding the nature of ultimate physical entities is to regard them as essentially having causal powers and capacities. We believe that souls are also reasonably understood as entities with essential causal powers and capacities. Given this ontology and the starting point that souls make choices to act for reasons, it follows (as we have already stated above) that the physical world must be open the causal influence of souls. What we need to be committed to (in terms of our dispute with naturalists) is making sure that there are no problems created for science by this picture of the world. We can find none (as we have repeatedly stated in referring to our critique of the causal closure argument). You seem to believe that if we can’t say more than this then dualism is completely disqualified. Well, it might be for you. It isn’t for us because we cannot see how (and here we are repeating ourselves) dualism undermines the framework and practice of science.
We will stop here. We affirm once again our total support for the practice of science and enthusiastically cheer for those who devote countless hours in their labs working to discover the cures for diseases that will improve our quality of life.
Thanks so much for engaging in this informative exchange.
Stewart and Charles
Intersubjective Empiricism and the Rational Basis for Naturalism
To justify its claims to objectivity, a worldview must hew to intersubjective empiricism. Naturalism does, Christian dualistic theism and other varieties of supernaturalism do not.
October 5, 2008
Dear Stewart and Charles,
Many thanks for your latest reply. Given this back and forth, I think we can now form a pretty clear picture of the differences between us. I’ll cover them more or less in order of appearance in your last installment, then close with a brief addendum on the issue that most divides us: what counts as reliable evidence.
You say “we are confident that naturalist accounts of purposeful explanation supplant purposeful explanation with causal explanation. In short, such accounts eliminate teleological explanation.” I am equally confident that completely natural, physical, soulless beings can and do have purposes, and that causal explanations don’t compete with or eliminate higher level teleological explanations described in terms of having mental states such as wanting, believing, hoping, etc. We legitimately attribute purposes to animals, perhaps even some complex machines (interesting question!), and other conceivable beings, artificial and natural, on the basis of their design and behavior. Agents don’t need anything immaterial or contra-causal to have goals and therefore to act purposefully, whether consciously or (perhaps) unconsciously. Of course, if you define purposeful behavior as requiring an immaterial soul that transcends causal explanation, then there are no purposes in nature. But if it turned out we didn’t have souls (an empirical question), it seems to me we’d still have purposes, just as do other (soulless) animals, so such a definition seems untenable, if indeed you hold it.
As I suggested in a previous response (see here), there’s no contradiction between being caused, material beings and having efficacious reasons, since reasons only cause behavior via the neural networks that instantiate them. Without a material instantiation, our reasons – our representations to ourselves of our motives, beliefs and circumstances – couldn’t have effects on the world. And the fact that our reasons themselves are causally determined doesn’t deprive them of causal power. Again, see Murphy and Brown’s Did My Neurons Make Me Do It? for a non-reductive physicalist account of how reasons “get a grip on the brain” such that strictly physical creatures like us can and do act purposefully. More generally, ascriptions of mental states play a legitimate, higher level role in explaining behavior even if causal closure holds, since mental states, for instance construed as representational states, need not involve anything immaterial (even if it seems they do from a first person perspective, about which see the next section).
You say: “The issue is what counts as evidence, and you will only allow ‘scientific, empirical, intersubjective grounds’ to count. You will only allow these grounds for evidence because you are a naturalist. We are not. Hence, what we need from naturalists is an argument for why naturalism is true. Again, the standard argument is the argument from causal closure to which we have authored our response in our book.”
Our differing notions of what counts as good evidence is, I think, the main disagreement between us. The reason I stick with scientific, empirical, intersubjective evidence isn’t because I’m a naturalist, but because I want the most reliable grounds for belief about what’s real, and I stick with those grounds for deciding all factual questions. The argument for naturalism is essentially epistemological, not from causal closure. Causal closure, as I argued earlier, is a defeasible methodological assumption which has its basis in desires for objectivity and explanatory transparency. Here’s the argument I’d make for the rational acceptability of naturalism and, by contrast, the irrationality of theism.
Surveying the various grounds for belief, it seems clear that that what might be called open intersubjective empiricism, exemplified by science, is the most reliable means for reducing the influence of subjective bias, wishful thinking, superstition, unfounded tradition, arbitrary authority, and other distorting influences on belief. If you want an objective view of things – and worldviews normally claim objectivity (see here and here) – you should insulate your beliefs from these influences as much as possible (which is why I call this the insulation requirement). Here is where we differ, since theists such as yourselves believe non-empirical, subjective intuitions about god, the soul and free will – first person data, as you call them – are reliable, undistorted reflections of reality. Naturalists think such intuitions often get reality wrong precisely because they are subjective: notoriously prone to personal and historical bias and without independent observational support.
Crucially, the judgment that intersubjective empiricism is a more reliable route to objectivity than intuition, revelation, tradition and authority is based on our everyday experience of the world, so it’s a worldview neutral judgment, made independently of and prior to naturalism. If I want to know how things work, and if I want to reliably predict events and outcomes in service to my purposes, it’s uncontroversially rational for me to stick with science and less exalted forms of intersubjective empiricism (asking my neighbor where to find good deals on Sony PlayStations); I don’t trust my observationally uncorroborated intuitions. Now, you say that first person data are reliable reflections of reality when it comes to the soul and free will: “…we see no reason to question them, unless one is already a naturalist.” But there are good, worldview neutral reasons to question them. Anyone not already wedded to dualist Christianity would want to know on what basis you have such confidence in subjective deliverances, when they are so often manifestly wrong (e.g., alien abduction, efficacy of anonymous prayer). They justifiably and rationally would want observational proof to back up your intuitions about the soul and free will, however commonsensical and natural they might seem to you. After all, your intuitions differ radically from those of some other religious denominations and those of non-believers. To depart from intersubjective empiricism when deciding matters of fact, especially such fundamental matters as the existence of the soul and free will, seems to me epistemically irresponsible and thus in need of further justification. This justification is what I’d be most interested in hearing from theists such as yourselves. Without it, naturalism – based in taking intersubjective empiricism as one’s epistemology for all matters of fact – is clearly the rational choice among worldviews claiming objectivity.
You say “Commonsensical appearances, such as that we think, hope, believe, and experience pain and pleasure, are not a product of bias and wishful thinking. The claim that they are is simply outlandish. Similarly, the commonsensical appearances that we are souls that make libertarian choices for purposes are not the product of bias or wishful thinking.” I didn’t claim, outlandishly (or if I did, I withdraw the claim), that it’s only wishful thinking to suppose we think, hope, believe, and experience pain and pleasure; we obviously experience and do all these things. Nor did I claim that it’s wishful thinking to suppose many people have the experience or appearance of being souls who make purposeful libertarian choices; they obviously do have such experiences. Rather, I claim that what’s likely wishful thinking is to suppose that the subjective experience of having a libertarian immortal soul – a very real appearance – corresponds to objective reality.
I absolutely agree, as you say, that “if we are going to try to reason with each other about these matters, …we [should] leave our hopes and fears out of it.” Leaving hopes and fears behind when reasoning and deciding about reality - meeting the insulation requirement - is exactly the mission of science, which along with critical thinking and philosophy is the epistemic basis for naturalism. But it isn’t the mission of Christianity, which has historically catered to humankind’s fondest hopes – for immortality, a personal god, reunion with loved ones in the hereafter, and an ultimately meaningful universe with us at its center. When it comes to putting aside human hopes in service to objectivity and explanation, science simply has no competition, and when it comes to putting them first for their own sake, Christianity exactly fills the bill, which makes it patently suspect as an objective take on reality. Again, this judgment is simply based on what one observes about science and Christianity, so it’s worldview neutral, not a judgment based in a commitment to naturalism.
You say “We are first convinced that the soul exists and makes libertarian choices for purposes and then go on to explain to our readers that the soul’s existence and causal activity implies that there must be a gap in the physical explanatory story. We are not first convinced that there is a gap and then posit the soul with its explanatory power to fill that gap…. Is there any reason to think that there cannot be a gap in the physical world into which this soul might insert its causal influence? Naturalists regularly respond that there cannot be such a gap because of the argument from causal closure.”
Naturalists respond, or should respond, not on the basis of the argument from causal closure, but on the basis that there’s no good, reliable (that is, intersubjective) evidence for something that could exploit such a gap. It’s the lack of evidence for anything immaterial or contra-causal, plus the explanatory opacity of dualistic proposals, that motivates causal closure as a defeasible methodological assumption. Scientists don’t and shouldn’t waste time hypothesizing an obscure explanatory role for immaterial entities for which there is no observational basis. Should good, intersubjective evidence of the soul come to light, confirming your subjective intuition that it exists, then of course they would drop causal closure like a hot potato. So again (and we at least agree on this) the issue boils down to our divergent notions of what’s reliable evidence. I think there are good, worldview neutral reasons to suppose intersubjective empiricism, exemplified by science, is a far more reliable reflection of objective reality in all its dimensions than first person data. When it comes to the soul, free will, God, and other fundamental matters of existence and human nature, you think the reverse, and I’m of course curious to know why.
You say that “…as best as we have been able to determine, the argument from causal closure plays the pivotal role in the naturalist’s argument against the commonsensical view and for naturalism.” I don’t think this is correct. Rather, as suggested above and reiterated below, the basic argument for naturalism is epistemological: wanting reliable beliefs about reality and transparent explanations, some folks make a rational cognitive commitment to intersubjective empiricism, which in turn generates for them a unified, non-dualist ontology: the phenomena of the natural world, with no supernatural realm above it. This makes them naturalists.
You write: “What we need to be committed to (in terms of our dispute with naturalists) is making sure that there are no problems created for science by this picture of the world. We can find none (as we have repeatedly stated in referring to our critique of the causal closure argument). You seem to believe that if we can’t say more than this then dualism is completely disqualified. Well, it might be for you. It isn’t for us because we cannot see how…dualism undermines the framework and practice of science.”
I agree that science has no argument with dualism, and that dualism doesn’t threaten science. As you know, and as noted in a previous installment, there are naturalistic dualists such as David Chalmers who think there are reasons to suppose there might well be two sorts of categorically different things in nature, mental and physical. Dualism is only disqualified (for the moment, and here I differ with Chalmers) since as far as I can tell there isn’t much going for it empirically and it has no explanatory contribution to make. So it doesn’t do much to meet desires for objectivity (that is, for intersubjective empirical support) and explanatory transparency, the main epistemic goals of naturalists. If naturalists tend to be non-dualists, that’s because philo-scientific investigation thus far tends to unify our understanding of what exists into a single reality, what we call nature. Should there ever be good evidential grounds for dividing reality into the categorically non-physical vs. the categorically physical, or the categorically natural vs. the categorically supernatural (these dualisms are of course strongly linked in your worldview, since God and the supernatural soul are non-physical), then I’ll join you in your dualism. Until then, for me, an ultimately undivided nature is what there is good grounds to believe exists, and it’s enough, more than enough.
As noted several times above, the primary difference between us is epistemic. You believe first person data, independent of publicly observable data, are reliable indicators of what’s objectively the case about reality. When it comes to the existence of god, the soul and free will, you reject what I’ve called the public object requirement: that evidence outside personal experience is required to validate that experience as veridical. You believe that with respect to these phenomena, subjectivity is a direct route to objectivity. But of course the very notion of objectivity is in contrast to subjectivity. We commonsensically and uncontroversially know that subjective takes on the world can be, and often are, biased, incomplete, distorted and variable. Gaining objectivity is precisely to call subjectivity into question, to check its deliverances against public, intersubjective data. No matter how many individuals might agree about the existence of the soul, or god, or free will based on personal experience, they could all be wrong absent such validation. Objective facts, as opposed to hunches, intuitions, and faith, are just those claims about reality that pass the test of intersubjective empirical confirmation. When building a picture of reality – a worldview that aims for objectivity – it seems cognitively irresponsible and irrational to suppose that certain intuitions, however strong and natural they might seem, are exempt from this test. This is especially the case when deciding the big factual questions about the fundamental structure of existence, the origins of life and the cosmos, and human nature and human agency. Theism, dualism and supernaturalism, to the extent that they are based in non-empirical claims about reality, cannot make good their pretensions to objectivity.
You will strongly contest this charge, claiming that certain first person data – intuitions about god, the soul and free will which point to dualism and supernaturalism – are reliable guides to reality in the absence of external confirmation. But naturalists want to know why. In asking this question we aren’t being harsh or unreasonable, only asking that theists and supernaturalists justify their evasion of what seem to us basic epistemic standards when it comes to formulating a worldview. If there are alternative standards that ground reliable cognition, we want to know about them.
I don’t expect this debate to be resolved any time soon, if ever, given the variability in human nature and culture. Some folks are raised to believe in god, some aren’t. Some are driven by the need for existential security, some by the desire for explanatory transparency. If we strongly identify with our beliefs, it’s difficult to admit we might be wrong and change our minds (I am no exception). But all this makes for some very interesting conversation, and I’m glad we share the live-and-let-live cultural space in which to have it. In closing, I can only say I look forward to its continuation.
No Quarrel Between Science and Christianity
October 31, 2008
Once again, we thank you for this informative exchange of letters. We will comment on and respond to various points in your letter of October 5, 2008.
We begin by saying that it is good to know that you agree with us that “science has no argument with dualism, and that dualism doesn’t threaten science.” This is significant because other naturalists disagree with the three of us about this issue. We focused on the causal closure argument in our book (Naturalism) because many naturalists argue that the role of causal closure in science makes it difficult, if not impossible, for a reasonable scientist to be a dualist who believes in libertarian free will and irreducible teleological explanation.
Your position is that while there is no quarrel between dualism and science, there is nevertheless no good reason to be a dualist who believes in libertarian free will (and, by implication, irreducible teleological explanation). At the heart of your argument for naturalism is epistemology, not causal closure. Before we address your position, we want to clarify once again that we do not argue that scientists do and should spend their time hypothesizing an explanatory role for immaterial entities for which there is no observational basis (the need for this clarification arises out of your claim that “Scientists don’t and shouldn’t waste time hypothesizing an obscure explanatory role for immaterial entities for which there is no observational basis”). As we stressed in Chapter 2 of our book, there is no reason for scientists who study the physical world in order to discover how physical entities interact with each other to hypothesize an explanatory role for immaterial entities.
What, then, about epistemology? You espouse a commitment to intersubjective empiricism, which stems from a desire for reliable beliefs about reality and transparent explanations. You state “that evidence outside personal experience is required to validate” experiences of the soul and free will (you call this the “public object requirement”). To bolster your claim, you maintain that “If I want to know how things work, and if I want to reliably predict events and outcomes in service to my purposes, it’s uncontroversially rational for me to stick with science and less exalted forms of intersubjective empiricism (asking my neighbor where to find good deals on Sony PlayStations); I don’t trust my observationally uncorroborated intuitions.”
Were we interested in good deals on Sony PlayStations we too would consult with our neighbors who have expertise in purchasing them. But if we are interested in knowing whether or not we are experiencing pain or pleasure, thinking about naturalism, fearing a collapse in the economy, hoping for a rebound in the stock market, we do not check with our neighbors, spouses, philosophers, scientists, or anyone else. We regard our first-person awareness as sufficient for knowing these things. In other words, for those things that matter most to us (our pleasures, pains, hopes, fears, thoughts), our first-person experience is our source of information. And this first-person experience is non-empirical in nature. If an implication of intersubjective empiricism is that we simply cannot know whether we are experiencing pleasure, pain, hopes, fears, etc., without empirical evidence from science or our neighbors, then so much the worse for intersubjective empiricism. We claim in our September 15, 2008 letter that it is simply outlandish to maintain that our belief that we think, hope, believe, experience pain and pleasure is a product of bias and wishful thinking. You respond that “we obviously experience and do all these things.” It is obvious. The relevant question here, however, is how do we know that we experience and do these things? Our position is that we know these things through non-empirical, first-person awareness of ourselves. At this point it is important to remember that brain science could not even get off the ground without acknowledging the first-person point of view. Brain science depends upon establishing correlations between brain events and mental/experiential events, and the source of the latter are the reports of subjects that are grounded in their non-empirical awareness of their own mental lives.
Throughout your correspondence with us, you stress the distinction between subjective and objective ways of knowing and claim that the latter is the superior (or the only way) of knowing. Your distinction seems to us to map nicely onto our distinction between first-person and third-person ways of knowing. We prefer our terminology because we think the subjective-objective terminology is often a source of confusion between epistemology and ontology. In our view of things, something known (epistemology) from the first-person point of view (subjectively, in your terminology) is just as objectively real (ontology) as something known (epistemology) from the third-person point of view (objectively, in your terminology). Because this is the case, the first-person point of view is just as much a source of what you term “world-view neutral reasons” as the third-person point of view. And let us be honest here: intersubjective empiricism is not the epistemologically world-view neutral position that you claim it is. It is a philosophically non-neutral point of view, and one that flies in the face of how human beings actually know certain objective facts, such as that they are experiencing pain, experiencing pleasure, thinking, hoping, fearing, desiring, etc.
What, then, about the existence of the soul and libertarian free will (and irreducible teleological explanation)? Well, if we can know from the first-person point of view that we experience pain and pleasure, and have hopes and fears, etc., why can’t we also know from that point of view that we are souls that make libertarian free choices for irreducible purposes? Why draw the line at pains and pleasures, hopes and fears, etc., and say that while these are knowable from the first-person point of view, the soul and libertarian free will are not? You say that our “intuitions [about the soul and free will] differ radically from those of some other religious denominations and those of non-believers.” Undoubtedly they do differ from the beliefs of naturalistic non-believers. It is our contention, however, that belief in the soul and libertarian free will is found wherever human beings breathe air. It is true that many individuals in what are historically thought of as more eastern traditions (e.g., Buddhism, Hinduism) deny the existence of the individual soul (as opposed, say, to the world soul), but it is important to emphasize that they admit that it seems to us that the soul exists and makes libertarian free choices. Like naturalists, though for different reasons, they claim that what seems to be the case with regard to the soul and our freedom is illusory. What one must do is examine their arguments for this claim to see if they are convincing. But once again, let us be honest here: if anyone’s position differs radically from that of typical human beings it is that of the intersubjective empiricist, a person who denies the existence of the soul, libertarian free will, and irreducible teleological explanation.
Finally, we turn to your comments about the epistemic basis for naturalism versus Christianity. You agree with our comment in our September 15, 2008 letter that “if we are going to try to reason with each other about these matters, . . . we [should] leave our hopes and fears out of it.” You then go on to state that the mission of science does leave out our hopes and fears when reasoning about reality and that this mission, along with critical thinking and philosophy, is the epistemic basis of naturalism. “But it isn’t the mission of Christianity, which has historically catered to humankind’s fondest hopes – for immortality, a personal god, reunion with loved ones in the hereafter, and an ultimately meaningful universe with us at its center. When it comes to putting aside human hopes in service to objectivity and explanation, science simply has no competition.”
We started off this letter by citing your acknowledgement that there is no competition between science and dualism and that dualism does not threaten science. We also believe that there is no competition between science and Christianity, in part because we believe that Christianity at its core assumes dualism, libertarian free will, and irreducible teleological explanation. We also generally agree with your comment that science leaves aside our hopes and fears when reasoning about reality. This is because, as we stated in the third paragraph of this letter, it is concerned with understanding the physical world and how physical objects causally affect each other. But when it comes to explaining why science tries to understand the physical world, we believe that reference to human hopes and fears is ineliminable. Humans desire health. They also fear disease and hope for cures of it. It is because of these epistemologically first-person data that science exists. If science is anything it is surely an enterprise that is seeking the causes of and cures for much of the human suffering in this world. (One might point out that science also exists because of humankind’s desire to know and understand the world. Our point is that this desire is precisely that: a desire. And like other desires it is directly knowable through non-empirical, first-person awareness of ourselves.
If science, however, finds the ultimate explanation for its existence in human hopes, fears, and desires, then Christianity shouldn’t be suspect just because it finds its ultimate explanation in human hopes, fears, and desires. As you state, Christianity caters to the hope for immortality. But what is wrong with that? Science caters to the hope for cures for disease. We desire immortality because we have a desire for a kind of perfect happiness that can be shared with others but is not found in this world. Is someone who acknowledges such a desire and yearns for its fulfillment epistemologically inferior or suspect? It is hard to see why. And, yes, we believe that God exists and created us for the purpose of experiencing this kind of happiness. Again, we can find no reason to think that possession of this desire for perfect happiness and the hope for its fulfillment makes us epistemologically deficient, any more than possession by scientists of the desire and hope for the cure of diseases makes them epistemologically deficient.
You might concede that while the existence of science arises out of human hopes, fears, and desires, the intersubjective empiricist method employed by science is superior to any other method in excluding those psychological events or states from influencing our efforts to understand the universe in which we live. We are not convinced of its superiority. It seems to us that our exchange of views with you in these letters is perfectly good evidence for the falsity of the view that human hopes, fears, and desires automatically undermine the quality of thought about topics like the soul, free will, the nature of explanation, and God’s existence. Are there people who allow their passions to overrule their reason when it comes to thinking about the soul, free will, etc? Certainly there are. But there are also scientists who allow their passions to overrule their reason when it comes to carrying out experimental work, recording data, etc. And just as it is possible to discover the influence of passions in the latter case and correct for it, so also it is possible to discover the influence of passions in the former case and correct for it (again, exchanges like these between the three of us suppress passions and elevate reason).
In conclusion, we reiterate the point with which we began this letter and with which you agree: there is no conflict between science and dualism, libertarian free will, irreducible teleological explanation, and (we now add) the existence of God. Indeed, we believe that science itself ultimately finds the explanation for its existence in human beings who are the subjects of an experiential life that is most directly knowable from the subjective or first-person point of view. This experiential life is as ontologically objective as the physical world studied by science. Indeed, without this experiential life, science wouldn’t even exist. That is as much an objective fact as any objective fact discovered by science. And we cannot believe naturalism precisely because it denies these facts.
With all good wishes,
Stewart and Charles
Objective vs. Subjective, Science vs. Christianity
November 7, 2008
Dear Stewart and Charles,
Many thanks for your letter of October 31. Since the start of this exchange the major issue between us has been the epistemic status of what you call the “first-person data” of subjective experience. Most of what I say below concerns this and the related issue of whether and how science and Christianity are in competition. You say:
“If an implication of intersubjective empiricism is that we simply cannot know whether we are experiencing pleasure, pain, hopes, fears, etc., without empirical evidence from science or our neighbors, then so much the worse for intersubjective empiricism.”
I’m not sure why you think intersubjective empiricism might deny the reality of subjective, first-person experience; it doesn’t and I never suggested it did. It only says that subjective experience alone can’t be trusted as a reliable indicator of how things objectively are. We need external validation via public objects to back up factual claims about the world outside our heads; this is intersubjective empiricism.
“In our view of things, something known (epistemology) from the first-person point of view (subjectively, in your terminology) is just as objectively real (ontology) as something known (epistemology) from the third-person point of view (objectively, in your terminology).”
Again, I’m not denying the reality of subjective experience, and naturalists need not and generally do not deny it. The fascinating philo-scientific question is how to explain subjective experience, aptly called the “hard problem” of phenomenal consciousness.
“…if we can know from the first-person point of view that we experience pain and pleasure, and have hopes and fears, etc., why can’t we also know from that point of view that we are souls that make libertarian free choices for irreducible purposes? Why draw the line at pains and pleasures, hopes and fears, etc., and say that while these are knowable from the first-person point of view, the soul and libertarian free will are not?”
Here’s why, and it’s the crucial, central point which you don’t seem to recognize. Although we have non-inferential knowledge that we undergo experiences – pains and pleasures, hopes and fears, etc. – such experiences aren’t necessarily accurate reflections of facts about the world outside the head. No naturalist would dream of denying that many people might have the vivid impression that they exist as a disembodied soul with libertarian free will, but what they do deny is that this impression is necessarily veridical. The (very real) experience of being a soul is one thing, whether it accurately models reality is another. This commonsense distinction between how things appear and how they really are drives intersubjective empiricism: we need confirmation via observation of public objects in order to know that our subjective intuitions and impressions aren’t mistaken about how things are objectively. To collapse this distinction, as you seem to be doing in the case of intuitions about the supernatural, is to court deception.
“…if anyone’s position differs radically from that of typical human beings it is that of the intersubjective empiricist, a person who denies the existence of the soul, libertarian free will, and irreducible teleological explanation.”
Yes, intersubjective empiricism takes us far from commonsense in some cases, but that doesn’t count against it. Over the last millennium, the view of typical human beings on many matters has been overturned and replaced with a scientific understanding. This is likely to continue as new facts come to light via public observation, experiment, etc.
“We started off this letter by citing your acknowledgement that there is no competition between science and dualism and that dualism does not threaten science. We also believe that there is no competition between science and Christianity, in part because we believe that Christianity at its core assumes dualism, libertarian free will, and irreducible teleological explanation.”
There’s no competition between science and dualism because dualism, as I suggested earlier in this exchange, is a possible (although not currently likely) conclusion science might reach on the basis of intersubjective evidence. But science competes with Christianity because both make differing factual claims about reality (e.g., about the existence of god, the soul, and free will) based on differing epistemologies and because Christianity has ontological commitments. If as you say Christianity assumes dualism, libertarian free will, etc. (Christian physicalists such as Nancey Murphy disagree with you about this), such an assumption is epistemically unwarranted from a scientific standpoint because science requires intersubjective evidence to support factual claims.
Science, unlike Christianity, makes no basic ontological commitments since it aims at clear explanations backed up by intersubjective evidence, wherever that leads us. Christianity, unlike science, doesn’t rely strictly on intersubjective evidence, but instead claims there are other ways of securing reliable knowledge about reality. As I’ve argued in this exchange and most recently in Reality and its rivals, this claim is unfounded: there really isn’t a good alternative to intersubjective empiricism if one is interested in reliably representing reality. Christianity purports to be objective, but its modes of knowing don’t pass epistemic muster. So again, it competes with science (and comes up short, if one is interested in reliable knowledge and clear explanations) both in its conclusions about the world and how it reaches those conclusions.
“Science caters to the hope for cures for disease. We desire immortality because we have a desire for a kind of perfect happiness that can be shared with others but is not found in this world. Is someone who acknowledges such a desire and yearns for its fulfillment epistemologically inferior or suspect? It is hard to see why.”
I think it’s easy to see why. The desire to cure disease prompts us to gather accurate information about how the world works, for instance how viruses mutate. On the other hand, the desire for god and immortality can, and often does, bias our perceptions and cognitions. We might take the religious experience of God’s presence as a true indicator of his existence because we strongly hope we will join him happily in the hereafter. Not to rigorously insulate such a conclusion about reality from the possible influence of such bias, and not to test that conclusion using public evidence, makes it epistemologically suspect.
“In conclusion, we reiterate the point with which we began this letter and with which you agree: there is no conflict between science and dualism, libertarian free will, irreducible teleological explanation, and (we now add) the existence of God.”
You’ve moved from saying I agree there’s no intrinsic conflict between science and the possibility of dualism (true), to saying that I agree there’s no intrinsic conflict between science and asserting the existence of the supernatural, e.g., the soul, libertarian free will, irreducible teleological explanation, God, etc. (false). As mentioned above, intersubjective evidence might conceivably come to light supporting some sort of dualism, such that our best theories countenance two (or more) categorically different sorts of phenomena. But that would still be a naturalistic theory by virtue of being science-based. Science can’t get us to the supernatural, since what it shows to (reliably) exist is what we call nature. It naturalizes what it shows to exist. To demonstrate the existence of the supernatural, you’d have to show that non-empirical, religious modes of knowing reliably establish the existence of something beyond nature. But that’s exactly what hasn’t been shown. These modes of knowing compete with science in purporting to be its rivals in representing reality and by coming to different conclusions about the existence of the supernatural (and, according to creationists and IDers, about how things happen in the natural world as well). But in this competition they fail to meet basic, worldview neutral standards of epistemic adequacy, which is how we judge competing ways of knowing. So if we want to get an objective view of things, we should avoid them.
“This experiential life is as ontologically objective as the physical world studied by science. Indeed, without this experiential life, science wouldn’t even exist. That is as much an objective fact as any objective fact discovered by science. And we cannot believe naturalism precisely because it denies these facts.”
I’ll simply repeat what I said above and earlier in these exchanges: that naturalism doesn’t deny the reality of our experiential lives, only that they are necessarily accurate models of the world outside our heads. Pointing this out, however, won’t make you more likely to believe naturalism because of your antecedent commitment to a supernatural ontology.
Given that in this latest exchange we’ve simply reiterated our basic disagreements, I think we can draw things to a close. It seems to me you trespass against a basic epistemological caution in not recognizing that first-person experience about the soul, free will, etc. might be mistaken as the basis for factual claims about reality, and thus needs intersubjective validation. You would likely observe this caution with respect to all factual claims except when it comes to theological claims about the supernatural, and I don’t see any good reason for carving out this exception. On the other hand, you think naturalists trespass against the natural view of ourselves by not according first person data the epistemic priority they deserve. As much as I’ve tried to cast doubt on this priority by pointing out the notorious fallibility of subjective intuitions, you stick with your guns. So be it. At least we have a clear view of our differences, which can remain safely unresolved in an open society that tolerates (sometimes even celebrates!) differences in worldviews. Many thanks for your tenacity and good will.
Best wishes always,