Wednesday, July 8, 2020

Other minds and modern philosophy

The “problem of other minds” goes like this.  I have direct access to my own thoughts and experiences, but not to yours.  I can perceive only your body and behavior.  So how do I know you really have any thoughts and experiences?  Maybe you merely behave as if you had them, but in reality you are a “zombie” in the philosophy of mind sense, devoid of conscious awareness.  And maybe this is true of everyone other than me.  How do I know that any minds at all exist other than my own?

One traditional answer to the problem is the “argument from analogy.”  I know from my own case that when, for example, I flinch and cry out upon injury, there is a sensation of pain associated with this behavioral reaction, and that when I say things like “It’s going to rain” that’s because I have the thought that it is going to rain.  So, by analogy, I can infer from the fact that you also flinch and cry out, and also say things like “It’s going to rain,” that you too must have thoughts and sensations of pain.  In modern philosophy this argument is put forward by writers like John Stuart Mill, and it is sometimes suggested that one can find something like it in Augustine’s On the Trinity, Book 8, Chapter 6.

The standard objection to this argument is that it amounts to the weakest possible kind of inductive inference, a generalization from a single instance to every member of a class.  There are eight billion people, and I have observed in only one case, namely my own, a correlation between thoughts and experiences on the one hand and bodily properties and behavior on the other.  So how does the inference from my own case to the rest of the human race not amount to a fallacy of hasty generalization?

But the idea that there is a “problem” here, and that the solution to it is a kind of inductive generalization, are artifacts of modern philosophical assumptions.  I don’t think Augustine was in fact giving an “argument from analogy” in the sense in which modern philosophers have done.  He was not offering a philosophical theory in response to a philosophical problem.  He was just noting how, in his view, we do in fact in everyday life know that other minds exist.  Here is the relevant passage:

For we recognize the movements of bodies also, by which we perceive that others live besides ourselves, from the resemblance of ourselves; since we also so move our body in living as we observe those bodies to be moved.  For even when a living body is moved, there is no way opened to our eyes to see the mind, a thing which cannot be seen by the eyes; but we perceive something to be contained in that bulk, such as is contained in ourselves, so as to move in like manner our own bulk, which is the life and the soul.  Neither is this, as it were, the property of human foresight and reason, since brute animals also perceive that not only they themselves live, but also other brute animals interchangeably, and the one the other, and that we ourselves do so.  Neither do they see our souls, save from the movements of the body, and that immediately and most easily by some natural agreement.  Therefore we both know the mind of any one from our own, and believe also from our own of him whom we do not know.  For not only do we perceive that there is a mind, but we can also know what a mind is, by reflecting upon our own: for we have a mind.

End quote.  Note that Augustine attributes to non-human animals the same kind of knowledge that other things are alive (and, presumably, conscious too) that he attributes to us.  But non-human animals do not engage in inductive reasoning.  So, it isn’t an inductive generalization, fallacious or otherwise, that he is attributing to us either.

I submit that there are at least three assumptions more typical of modern philosophy than of ancient and medieval philosophy that underlie the idea that there is such a thing as a “problem of other minds,” and that our knowledge of other minds is grounded in a kind of inductive generalization.

The first is that genuine knowledge is always a kind of “knowing that” or propositional knowledge, as opposed to a kind of “knowing how” or tacit knowledge.  (See Aristotle’s Revenge, pp. 95-113 for discussion of this distinction.)  Not all modern philosophers take this view, but it is criticized by thinkers like Wittgenstein, Heidegger, Michael Polanyi, Hubert Dreyfus, et al. as typical of a Cartesian conception of rationality.  The idea is that knowledge can always be analyzed into the possession of explicitly formulated propositions and inferences.  If ordinary people don’t seem consciously to be entertaining such propositions and inferences, then it is sometimes claimed in response that the propositions and inferences are nevertheless present below the level of consciousness (say, as the rules and representations of a computer program implemented in the brain).

It is natural, on this model of rationality, to think that knowledge of other minds must involve some kind of inference.  Wittgenstein’s critique of the whole debate over the problem of other minds might be read as claiming that knowledge of other minds is in fact a kind of tacit knowledge rather than a propositional or inferential kind of knowledge.  On this view, the debate simply misunderstands the nature of our knowledge in this case.

A second relevant modern assumption is that there is a metaphysical gap between matter and consciousness that makes inferring the presence of the latter from facts about the former inherently problematic.  The standard modern conception of matter inherited from the early modern “mechanical philosophy” facilitates this assumption.  Matter is taken to be characterized by quantifiable primary qualities alone (size, shape, motion, etc.) and lacking anything like qualitative secondary qualities (color, sound, heat, cold, etc.), at least as common sense understands them.  Hence it becomes mysterious how the qualia of conscious experience could be material, and knowledge of a thing’s material properties comes to seem insufficient to ground an inference to its having any mental properties.  (This is, of course, a topic about which I’ve written many times.)

A third relevant assumption – and the one I want to focus on here – involves what we might call a Baconian conception of our knowledge of the natures of things, as opposed to an Aristotelian conception.  For the Aristotelian-Scholastic position against which Francis Bacon reacted, common sense is more or less right about the natures of everyday natural objects, even if it isn’t very sophisticated.  The ordinary observer correctly grasps what it is to be a stone, a tree, or a dog, even if it takes scientific investigation to understand these natures in a deeper and more sophisticated way.  On this view, the senses are, you might say, friendly witnesses and just need an expert to ask the right questions in order to find out what else they know.

For Bacon, by contrast, the real natures of things are hiding behind false appearances, and sense experience is a hostile witness who must be tricked and threatened into revealing what it knows.  Hence Bacon’s emphasis on slow and painstaking observations under artificial conditions, and the gradual working up from them to a general conclusion before one can claim to know what a thing of a certain kind is really like.

Also relevant is the modern idea that understanding the physical world is not a matter of uncovering the essences of things, but rather a matter of identifying the laws that relate observed phenomena.  This involves formulating a general theory, deriving predictions from it, and then testing those predictions by way of a series of observations and experiments.

If that is the way that knowledge of the empirical world works, then naturally it comes to seem that whether other people really have minds is not as clear-cut as common sense supposes, and some kind of theoretical inference must be deployed in order to justify the supposition that they do.  The meagerness of the evidential base in one’s own case in turn becomes a major problem, insufficient as it is for the construction of a Baconian inference.

Now, as contemporary neo-Aristotelian philosophers of science point out, this is not exactly how science in fact typically proceeds.  To be sure, the Baconian emphasis on making observations under artificial experimental conditions certainly does feature in modern scientific method, but the idea of piling up instances before drawing a general conclusion does not.  As Nancy Cartwright has argued, once the right experimental conditions are set up, multiple observations are not seen as necessary.  She writes: “Modern experimental physics looks at the world under precisely controlled or highly contrived circumstance; and in the best of cases, one look is enough.  That, I claim, is just how one looks for [Aristotelian] natures” (The Dappled World, p. 102, emphasis added).

Now, if few observations or even a single observation are all that is needed when the circumstances are right, then we have an essentially Aristotelian rather than Baconian approach to how many cases are needed in order to determine the basic nature of a thing.  The difference is in the nature of the cases, not the number of cases.  The Aristotelian thinks that ordinary observation isn’t especially liable to get the nature of a thing positively wrong (even if it does not go very deep either) whereas the Baconian thinks that ordinary observation’s getting things positively wrong is a serious possibility.

Now, suppose the Baconian were correct about observation of things other than ourselves – stones, trees, dogs, etc.  Suppose that common sense is indeed prone to getting the natures of these things wrong (which is, again, a stronger claim than just saying that common sense has only a superficial knowledge of their natures, which the Aristotelian would not deny).

Still, it wouldn’t follow that we are likely to get things wrong about our own nature, and prima facie that is unlikely, since in this case the knower and the thing known are the same.  Of course, one could argue that there is a dramatic appearance/reality gap even here, but the point is that you would have to argue for such a claim.  It is not prima facie what we would expect. 

In that case, though, why couldn’t one know just from one’s own case that a physiology and behavior like ours go hand-in-hand with a psychology like ours as a matter of human nature?  And then, applying this knowledge of human nature, why couldn’t one thereby know that other human beings too have mind’s like one’s own?  “Problem of other minds” solved.

Again, some philosophers would of course argue that things are not as they seem even in the case of our apparent knowledge of our own minds.  But the point is that that is simply not a plausible default assumption.  There is a presumption in favor of our having a correct understanding of our own nature, and (given what I’ve just argued) there is, accordingly, a presumption in favor of other people having minds just like our own. 

That suffices to undermine the idea that there is a frightfully difficult “problem of other minds.”  The correct description of our situation is not that we don’t have good grounds for believing in other minds, and therefore have to cobble together some solution to this problem.  It’s that we do have good grounds for believing that there are other minds, and therefore the philosopher who thinks otherwise can make things seem problematic only by making a number of tendentious modern (and, I would say, wrong) philosophical assumptions.


  1. This sort of paranoia about reality infects a lot of modern thinking. Bacon and Descartes are truly the fathers of the Enlightenment and all its ills.

    1. The father of the Enlightenment and all its ills is Martin Luther.

    2. Spoken like a true Roman Catholic.

    3. Martin Luther and John Calvin were the twin ushers of the Apocalypse. Things would gave just gotten better and better without them.

    4. I'd pin it on Ockham and the Nominalists, but that's just me.

  2. She writes: “Modern experimental physics looks at the world under precisely controlled or highly contrived circumstance; and in the best of cases, one look is enough. That, I claim, is just how one looks for [Aristotelian] natures”

    I am not sure this is quite enough of an argument. In the cases where just one observation is enough are, (at least arguably), the cases where the experiment is designed so that one observation gives a clear counterexample to the hypothesized X. Suppose we are examining a K object and we hypothesize that it has X feature. If X is true, then in the experiment Y should result, and if we see Y result, then X may indeed be true (but it is not proven because possibly some alternative Z would also account for Y resulting). But if ~Y results, then X cannot possibly be true. That's how the experiment is designed. When we observe Y happen, we know that one counter-example observation is enough to disprove hypothesis X.

    But a counterproof to an hypothesized feature X of the nature of K only tells us one thing about the nature of K, and a negative truth at that: that X is not true of it. That might move us farther along to understanding K, but it would not reveal K's nature to us all by itself.

    It seems to me that we Aristotelians think we apprehend a nature through several observations, because one observation alone cannot generally reveal so much of the thing as to enable the agent intellect to grasp the nature of the thing.

  3. Does anyone argue that the fact that we can learn complex abstract truths from others without any previous reflection necessitates that there are minds other than our own?

    1. I would say that it necessitates that there are other minds, not necessarily that a particular instance of "person" has a mind. After all, the directedness of language found in a book necessitates a mind, but no one would attribute a mind to a book. Proving that our common sense is justified in assuming others have minds seems to require the sort of argumentation for essentialism that Prof. Feser gave in the article.

    2. But if there are other kinds in general, that does bolster the claim that this particular person has a mind, correct?

    3. It certainly bolsters it, but as the discussion of the Turing test below suggests, it doesn't give us a definitive guide for how to tell if what is in front of us is a mind. That takes the extra work.

  4. Couldn't someone use this kind of reasoning to claim that AI is conscious? If someone created a fully realistic robot and gave it sufficiently advanced AI that it behaved exactly as a human, wouldn't the reasoning of this post make it reasonable for an observer (who didn't know it was a machine) to "know" that the machine had a mind? Asking for a friend...

    1. A friend named Turing, no doubt.

    2. It wouldn't because of what it means to be a machine. Machines do not have representation or the ability to mean or intend something in the way that we do as rational creatures.

      Clearly you can convince someone talking to a machine that they are talking to a person, but you can only do that because of your own mind, which can convey meaning through the conventional symbols that the machine uses to "interact" with the person being fooled. The person can only be fooled into thinking that the machine is a mind because there is a mind (or more than one) behind the machine producing something at least remotely mind-generated that the person rightly recognizes as mental.

      I would say the Turing test is at best analogous to hearing voices around a corner, walking around the corner and finding a recording of someone talking. The speaker is coming into contact with a mind, but only proximately rather than directly.

    3. Casual Thomist,

      I'm imagining a scenario in which I land on a remote island which, unbeknownst to me, is filled with humanoid machines. If I'm justified in saying that I KNOW other people have minds because they exhibit the same reactions/behaviors as me, then why could I not say that I KNOW that the (robot) people on this island have minds? Why don't I need to go cutting into everyone to make sure they don't all secretly have circuit boards inside their heads?

      Basically, how could I know the difference between a philosophical zombie and a real live person? I would have to agree that if we know that the other person is a human that we are quite justified in believing they have a mind, but how exactly would we convince a skeptic that everything that appears human actually is human?

      Something like that... I'm rambling.

    4. @Anonymous
      Yikes! Didn't mean that to leave this sitting for three days! Sorry about the delay in response. I would say that there is a possibility that you wouldn't know the difference between a philosophical zombie and a person when encountering them... except that philosophical zombies aren't metaphysically possible.

      As for telling the difference, I would say that when me make such judgements, there's always a small added caveat stating something such as which amounts to, if what I think is true about the composition of this being is true, then it must be of the type that I am insinuating. People can be fooled into thinking something has intelligence when it really doesn't, but we can have at least enough faith in our senses to determine that based on what they tell us we can make some pretty good inferences. Again, if its set up like me, it is like me would be the general formula, even if the actual argumentation is more complex.

  5. OP
    The “problem of other minds” goes back to Descartes, cogito ero sum, and a great many others who have considered what there is about the extramental reality that one can, each of us can, I can, be certain of, absolutely certain of. The answer is, of course, that we cannot be absolutely certain of the accuracy of our perceptions, including our inferences about the reality of and the nature of other minds.

    Philosophical naturalism, or what is sometimes called the mechanistic philosophy, is entirely coherent and free of self contradiction when properly formulated and expressed.

    We must, if we wish to make further apparent progress, provisionally postulate the basic reliability of the human senses. From there we can work to identify and correct for distortions of our sense data, and use technological means to vastly extend the capabilities of our unaided senses.

    Further, we can communicate and estimate that given the high complexity and correlation with our own minds, the expressions of others strongly indicates that these apparent other minds are almost certainly real and very much like our own.

    Now, there are those who are uncomfortable with the use of so many qualifiers of uncertainty and doubt. Ok, fine, one may wish for some means to be more accurate and to find an anchor in this universe, a source of absolutely certain truth about the apparent extramental reality, and perhaps you feel you have reasoned your way to such a source of absolute truth, your notion of god. You haven't, of that I am certain :-)

    1. The answer is, of course, that we cannot be absolutely certain of the accuracy of our perceptions, including our inferences about the reality of and the nature of other minds.

      Philosophical naturalism, or what is sometimes called the mechanistic philosophy, is entirely coherent and free of self contradiction when properly formulated and expressed.

      Have you read much of Prof. Feser's work, either his older blog posts or his books and articles? If so, you would have to realize how bold both of these claims are.

      I'll start with the first: while clearly there is the issue of radical skepticism which has plagued human thought since it first became systematized, let me ask you one question: what reason could one have to doubt that sense experience is incorrect? Answer: only sense data, which, if the proposition is to be applied consistently, would cast doubt on the coherence of your original premise. Our sense data has to have sufficient reliability even to be fooled; we can argue about how much reliability that is, but even Democritus famously lamented that such doubts famously undermine their very source. So, I would assert with Aristotle and Aquinas, before we can even start doubting systemically the reliability of our senses, we need to ask the question: why? What reason could one have to doubt them? (To my fellow Thomists, if this explanation is lacking, please supplement it)

      On to the second point. Correct me if I'm wrong, but the mechanistic worldview seems to be nothing more at this point than the assertion that the only characteristics of matter that can be classified as objectively real in mind-independent reality are those which can be mathematically and scientifically studied. If you are referring to an essentialist naturalism or something else other than the above, please say so as that constitutes something different in the taxonomy of philosophy I have learned.

      I won't get in to the minutae of the problems of qualia and the mind-body problem, etc which are created by such a stance as taken above,as Thomas Nagel and Feser himself have already argued far more persuasively than I ever could; see here:

      Instead, I will just ask one question: what is a law of nature? The entire mechanistic philosophy of nature rests on laws of nature doing the explanatory work for why things act the way they do. And if they are anything other than essentialism in disguise, then they are either hollow placeholders or ultimately incoherent. So I ask again, @StardustPsyche, what is a law of nature?

    2. Casual Thomist,

      Seriously, please don't muck up this thread with SP's numerous, massive, and half-pertinent posts. I realize it is tempting to correct him; resist the temptation.

    3. Causal Thomist
      "what reason could one have to doubt that sense experience is incorrect?"
      If there is to be a god at all it might just as well be me, in which case you are merely a figment of my divine imagination.

      Since no logical argument can be made to disprove that speculation then there is doubt as to whether my perceptions of extramental reality are realistic.

      "the mechanistic worldview seems to be nothing more at this point than the assertion that the only characteristics of matter that can be classified as objectively real in mind-independent reality are those which can be mathematically and scientifically studied."
      That may be one version, but I think the good folks here might call that scientism. I think that view is anthropocentric and egoistic. Our maths and science are very obviously limited, so there is no reason to suppose a priori that all reality must be subject to our present state of scientific investigation.

      “before we can even start doubting systemically the reliability of our senses, we need to ask the question: why? What reason could one have to doubt them?”
      Beyond the “I am god” speculation our senses are very clearly highly inaccurate, on the provisional assertion of the basic reliability of the senses. A great many sensory distortions have been studied, and various technological means have been devised to compensate for our sensory deficiencies.

      The technique, once one provisionally stipulates the basic reliability of the human senses, is cross checking, communicating with others, and comparing our sense experiences with technologically measured parameters. Over a wide range and large number of trials and measurements patterns of inaccuracies in our senses become apparent.

      “what is a law of nature?”
      Nobody knows why the stuff of the universe interacts and progresses as it does, that is a great unsolved riddle, the origin of existence including the manner in which material interacts and progresses. All attempts at solving this riddle that have yet been generally published only lead to further irrational assertions.

      But I can say what laws of nature are not, they are not the formulations found in physics books. All modern physics, that is the models described mathematically in physics books, are incomplete descriptions of an as yet undiscovered underlying reality.

      So, I agree with Dr. Feser that we are justified in concluding that other minds are real, but that justification rests upon a provisional postulate, the basic reliability of the human senses.

  6. OP: "It is natural, on this model of rationality, to think that knowledge of other minds must involve some kind of inference."

    Whether or not it must, it certainly can involve some kind of inference, and as soon as we ask for a justification of our knowledge it must, even if that justification consists just in asserting that the knowledge is 'common sense' -- which might be rather like asserting that we know what is right and wrong by intuition, even though people evidently have conflicting intuitions (i.e., problematic). But then we have to come back to establishing first principles, which is what Descartes' project was all about.

    OP: "Wittgenstein’s critique of the whole debate over the problem of other minds might be read as claiming that knowledge of other minds is in fact a kind of tacit knowledge rather than a propositional or inferential kind of knowledge. On this view, the debate simply misunderstands the nature of our knowledge in this case."

    Sure, but is this view remotely plausible or satisfying? We don't know THAT there are other minds? We're still weirdly, wildly, implausibly deceived on this view (worse than in Bacon's case), since we certainly don't generally know that we don't know that there are other minds; i.e., we're pretty universally deceived in our thinking that we do have propositional knowledge about this kind of thing.

  7. We do know there are other minds, but I don't think the technical philosophical problem can simply be "avoided". We don't know it with 100% Cartesian certainty. We do know it with a practical certainty, however - and the justification comes from Phenomenal Conservatism. That's my view.

    These problems were very useful for refining our understanding of epistemology over the centuries, and I think we're in a good place today. Phenomenal Conservatism is the truth, I believe, and analytic philosophy has seen real progress in epistemology; it is better today than it was at Aristotle's time, or even Aquinas's time. That's my view. It's just the metaphysics of our contemporaries that is messed up; thomistic metaphysics is superior and more explanatory.

    1. Atno,

      What do you see as "progress"? Is "progress" merely returning to common sense after a long detour through the weeds, or is it something more than that? I'm not quite sure what you mean by phenomenal conservatism.

    2. @TN

      "In epistemology, phenomenal conservatism (PC) holds that it is reasonable to assume that things are as they appear, except when there are positive grounds for doubting this. (The term derives from the Greek word "phainomenon", meaning "appearance".)"

      To be honest, it does look like a pretty reasonable principle to me, it reminds me of Plantinga Reformed Epistemology(who also makes sense to me). My only problem was Huemer use of it to ethics, but i just read one text from him, so who know.

      I mean, the average person does reason like that and philosophers normally do too, even the skeptic does not doubt some things.

    3. OK, Thanks. I was asking Atno to explain a little more: is "practical certainty" the same as, or a little different than phenomenal conservatism? How would one argue successfully that common sense is not "the truth" without immediately running into a problem? And has the progress of epistemology been due to a return to common sense (i.e. phenomenal conservatism) or something else.


    4. My only problem with phenomenal conservatism is not the principle itself, but the fact that I have seen it used to justify a rejection of the PSR, which though, in my view, is actually presupposed by it

    5. Dominick,

      Ya can't deny PSR without using PSR. People are just insane. What occupies most of my time is not these typical metaphysical issues, it's the mysterium iniquitatis.

    6. TN,

      I believe we've had progress in that we can now cogently explain how we can be justified in believing in common sense propositions and many other things. No one (well, almost no one) ever truly doubted the existence of other minds, for instance, but there was still the problem of how exactly to justify such a belief. The ancients didn't seem to have an answer either, they just seemed to accept it - Aristotle appeared to be a particularist, "okay, whatever is the case here, we KNOW we can generally trust our senses, so let's move on to actually interesting metaphysical issues".

      We had significant progress when Moore came along with his "proof of the external world", which was the technical observation that, whatever philosophical story we have, we are more certain that we have two hands than that any argument for skepticism could be plausible (even if we don't know exactly where the argument goes wrong). This logically justifies us in making a "Moorean shift" - if skepticism were false, we wouldn't know that we have two hands, but we are much surer that we have two hands than we can be of the skeptical argument, so we can be sure this skepticism is somehow false.

      We made even more progress when we got to Plantinga's reformed epistemology, etc., and finally Phenomenal Conservatism. Phenomenal Conservatism (henceforth PC) is really what is at play in justifying our beliefs, including our very sure belief that (e.g.) we have two hands.

      PC is the following: "if it seems to S that P, then S has some justification for believing that P". So if it seems to S that he has two hands, he will have justification for believing this in the absence of defeaters. The justification conferred is proportional to how strong the "seeming" is, with the consideration of potential defeaters.

      We believe other people have minds because it really does seem to us that other people have minds. There is nothing else to it, generally. In general don't really "infer" or have to infer that other people are conscious as a best explanation to their behavior - it just seems to us, obviously, clearly, that other people have minds, no matter what skeptical argument might be proposed.

      To me, PC is strongly self-evident in the way the principle of non-contradiction is self-evident. I know with 100% Cartesian certainty that contradictions are impossible; when I understand the terms, I understand the principle is true. Likewise, when I understand the terms of PC, I understand that it is true. If something really appears to be true, a subject has some justification for believing it to be true. This is self-evident to me.

      Being self-evident, we can then identify PC as the foundational rock upon which all common sense metaphysical, ethical and natural propositions can be grounded and justified.

      So I do think that we've made lots of progress in epistemology. We now have a much better and more consistent, worked out, and complete grasp of it than the ancients and medievals did.

    7. Also, one important note for understanding PC: it is *not* a principle of inferential justification. By this I mean that we do not *infer* things on the basis of a particular occurrence of a seeming. It is not as if we reason "this thing is probably true BECAUSE it appears to me to be true" which would obviously be problematic. Rather, the subject simply has justification for believing in whatever appears to be true, because (of course) it is rational and justifiable to believe that which really, really appears to be true to you.

      This is a conceptual point that is very hard to put into words without making it confusing. Once you "see" it, you see it, and understand the difference.

      For those interested, I recommend Michael Huemer's book "Skepticism and the Veil of Perception".


      How is that a problem? If it really seems to someone that PSR is false, that person will have justification to believe that it is false. Of course, they will be wrong, because PSR is true. But if it somehow appears false to them, they'll have some justification for believing in their intellectual presentation/appearance. I reckon most adults would find it that PSR actually seems to be true to them, when they reflect on it. Or even that they'd have some defeaters, if PSR were to appear false to them. By simply thinking about PSR and reflecting on it, most people will come to see that it is true, or at least that it is plausible and probable to a good degree. For instance, just thinking that something cannot magically come into being from absolutely nothing, without any cause.

    8. Oh, and TN, by "practical certainty" I mean something quite specific, at least it's an idea of mine.

      There is such a thing as Cartesian or mathematical certainty, we might say. This is the certainty we can say is TRUE 100% certainty. We can know a few things with Cartesian certainty: that something exists; that I exist and think (the cogito); the law of non-contradiction; 2+2=4 and the most basic mathematical and geometrical facts; the principle of phenomenal conservatism (so I argue). That's the stuff we can have 100%, mathematical certainty about.

      "Practical certainty" refers to propositions which we do not really know with mathematical certainty, but which are still painfully obvious, and which we cannot seriously doubt. If I'm being honest, I could be in the Matrix; I could be deceived by a Cartesian demon right now into thinking I am having this conversation with you. But this seems ridiculously crazy to me. I KNOW I am talking to you. I KNOW my most recent memories are correct. I KNOW other minds are real. These constitute a practical certainty even though I could possibly """"doubt"""" these propositions.

    9. Ok, thanks for the reply. After Talmid’s post I read a little on Plantinga’s Reformed Epistemology (which I initially, wrongly assumed to be some sort of defense of Calvinism. Zing!) and I believe I get the gist of it. You say, “It is not as if we reason ‘this thing is probably true BECAUSE it appears to me to be true’”—which would be a type of crude relativism—the argument is more subtle and is appealing to fundamental presumptions. Any argument against fundamental presumptions would be less compelling than the fundamental presumptions themselves.

      While the details may be interesting to egghead philosophy types, to most people you run into every day the issue can be painted broadly as mere common sense without doing any harm. It took 500 years to get people this screwed up. It will take a long time to get them back.

    10. It is more like an experience than just a presumption. Of course we are correct in presuming that the external world is real, as well as other facts of common sense. But why, exactly? If I introspect really strongly on the reasons why I believe (for instance) that my memory of yesterday is true, and that other people have minds, etc., I'll find it that it's because *it seems to me that these things are true*. This "seeming" is a kind of sui generis phenomenal event/state. Some authors, such as Bengson, call it a "presentation": the fact is presented to me. It is hard to describe it with more precision than that (perhaps that is a task for phenomenologists), but it does happen. It simply appears to me that other people have minds; I could be completely wrong, what seems to be true isn't necessarily true, perhaps my intellectual presentations/appearances are mistaken here. Perhaps I really am deceived and it just seems as if other people have minds and I am not dreaming. Perhaps. But it *really* doesn't *seem* to be the case. It really does seem to me that such and such is true. And if it really strongly seems to someone that such and such is true, what more can we ask for, for justifying responsible and reasonable belief?

      Someone might be in the desert and have a mirage. Right, but in this situation most adults know about mirages, so they'd have a defeater for their seeming. There will be intellectual tension. But when there's no such a defeater, and it *really* seems to us that something is the case, then of course we are justified in believing it. Because it really, seriously appears to be true!

      This principle is self-evident to me, and it gets rid of all skeptical scenarios. In addition, I am convinced that it captures the way common human knowledge actually works. THIS is why people believe they aren't being deceived by a Cartesian demon or dream, even when they entertain such scenarios. Because, no matter how ingenious these skeptical scenarios are, it still *seems* to us that they are false. We have a specific experience/perception of the world in such cases. It is close to our Cartesian, perfect intuition of first principles of logic, but weaker. It is as if reality presents itself to us as really, truly being in a certain way. We might be mistaken. But it doesn't seem like we are. It seems the skeptic is crazy; it seems we are not having a vivid dream. This is how common beliefs really are justified.

    11. Atno,

      It falls prey to the empirical problem Koons and Pruss alluded to in their recent paper, as well as Koons in his engagements with Oppy. If you don't have PSR there is by itself no real justification is given for your conviction that what seems to be really is that way. In that sense the phenomenal conservatism is applied without it being grounded. Take Oppys formulation of the PSR for example: Every non-first state needs a cause.

      This doesn't defeat the skeptical problem that maybe your state of perception could be the first cause and thus phenomenological conservatism would have a defeater it wouldn't have if it were supplemented with a full blown PSR. I also of course agree that the skeptical scenario is ridiculous, but I'd argue that the ridicolousness is due to the fact that we implicitly presuppose PSR.

      Now what if we apply PC to an event to which we assume that its defeats PSR? Then, given the falsehood of PSR, we have an undercutting defeater to the reasonableness of PC and we'd fall into scenarios like above

    12. Yes, I think I'm on the same page. When I mentioned "fundamental presumptions"(perhaps not the best expression), I believe that is a way of speaking of it as a generalized principle when applied accross individuals: I know it's true for me because I experience it, but I'm in the position of necessarily presuming that this senario holds for other minds as well, even though such a presumption begs the question if it isn't just a necessary, fundamental assumption. You seem to touch on the same sentiment when you say "This is how common beliefs really are justified." Because once you speak of "common beliefs", you are assuming the existence of other minds and that they have the same experiences.

      I like the second paragraph about the "defeater", but I think even there we have no choice but to make a "fundamental presumption" that we would know a "defeater" when we saw it, and that we really have an even more foundational knowledge of objective reality (a "view from nowhere", as Nagel says).

      The skeptic can't get around any of this because he must make the same assumptions in order for his objection to even get off the ground.

    13. Nonetheless, this is still stuck on an analytic level, I know. As I wrote below: The end isn’t math [i.e. analytic explanations]; the end is contemplation.

    14. Dominik,

      If the skeptical scenario seems to me to be crazy, it is not really a defeater. This might have to lead me to conclude PSR is true as well, if it is true ~PSR would give us defeaters. But first and foremost we recognize that this would be a problem ("skepticism bad") because we have intellectual presentations of the falsity of skepticism.

      Phenomenal conservatism gets around any possible skeptical scenario, because it immediately justifies whatever seemings we have. If X is what really seems to be the case for you, you are justified in believing that X.

      It is important to note that the phenomenal conservative rejects the idea that we are only justified in believing that P by method M iff our appearance of P wouldn't also be present if M were unreliable. We don't need to first know the reliability of M. This is because Phenomenal Conservatism is NOT a principle of inferential justification, which is crucial.
      It is not as if we are justified in believing that P because P would somehow be likely given our seeming-that-P. It is not an inference. We are justified in believing that P because it really seems that P, that's all.

    15. Yeah, Atno is right. What I said above isn't relevant. Dominik and I are both trying to ground knowledge in a way that is not necessary according to PC. I'll have to look into it more. Thanks for the help.

    16. To be clear, I do think that rejection of PSR can lead to skepticism, even with the standard phenomenal conservative justification. Maybe this is what Dominik was getting at. I just wanted to make it clear that we shouldn't get the order reversed; we don't believe in PSR to then have phenomenal conservatism; phenomenal conservatism is what grounds all our standard beliefs, some of which (upon closer inspection) will end up requiring PSR in order to avoid inconsistency.

      We have the argument for PSR from skepticism precisely because, through PConservatism, we realize that "skepticism is false". Then we can be forced to adopt PSR in order to avoid an inconsistency. Because ~PSR can indeed be a defeater. It'd be like "everything seems to be to be working in accordance with appropriate causes and effects... but I also don't think it's improbable for things to pop into being uncaused (because of not accepting PSR)". That would be a problem; that would indeed give us a defeater, so we have an argument for PSR. But, to be clear, phenomenal conservatism is what comes first.

      If you have actual, positive reason for thinking your appearances/intellectual seemings are unreliable, then of course you have a defeater. So the argument from PSR is about establishing that, without PSR, we would have such positive reasons.

      But the traditional skeptic (a la Descartes) isn't giving us positive reasons for questioning the reliability of the senses. He is asking us WHY we can even in principle trust any appearances; he is defensive, so to speak. "You COULD be dreaming. You COULD be deceived by a demon", etc. Correct, but the "could" doesn't mean it's a scenario that is not-improbable. Skeptics presume the following principle:

      "One cannot know that P by means of method M if, if P were false, method M would still say that it was true".

      If one accepts this principle, then skepticism is inescapable. "If you were a brain in a vat, your delusions would still be telling you you're not a BIV, so you cannot trust them!". This is the trick principle behind skepticism. And it is this that Phenomenal Conservatives reject. I could indeed be a deceived brain in a vat, but it is still the case that it really seems like I'm not a BIV, and this can justify my belief that I'm not a BIV. Because it is not as if S is "inferring" that he's not a BIV based on the particular phenomenon of "S is having a seeming that he is not a BIV". It is not an inference like that; S doesn't care that he is having a seeming, so to speak. Rather, reality just is such that it really appears to S to be a certain way. And because P appears to be true to S, S has justification for believing that P.

      This is the most complicated (and most crucial) thing about phenomenal conservatism. Once you understand it, you get it. It's hard to put into words. The thing is that it's self-evident that, if P really appears to be the case, then we have justification for believing that P. And it has nothing to do with any inference of P from an appearance. It just is P being presented to us as probable or true.

    17. Yeah, the brain in the vat is a good example: if I believe I am not a BIV, and I have absolutely no grounds or evidence to conclude otherwise, then I am, in fact, not a BIV.

      If an opponent says "wait, but it could be otherwise", we've already stipulated there is no evidence for that conclusion.

  8. ". . . some philosophers would of course argue that things are not as they seem even in the case of our apparent knowledge of our own minds. But the point is that that is simply not a plausible default assumption."

    No reductive skeptic can start with reductive skepticism. There must be some default starting assumptions—that which we can’t not know. There is a type of thought that prevents all further thought, and the modern world has drunken freely.

    “No sceptical philosopher can ask any questions that may not equally be asked by a tired child on a hot afternoon.” GK Chesterton

    1. As a child I asked what sense it made that god would send a part of himself to Earth, then get himself killed as a sacrifice of himself to himself, and that would somehow make it so god could forgive me.

      Why couldn't he just forgive me? How does somebody else getting killed pay for my sins? Isn't that just scapegoating? And how was it a sacrifice or a killing at all since Jesus lives in heaven and god knew that before he sent himself to Earth as Jesus so god didn't sacrifice anything and Jesus did not really die.

      So, the absurdity of the Christian position is glaringly obvious even to a skeptical child.

      I also wondered about other people's thoughts and feelings. Their words describing thoughts and feelings seemed like mine, they seemed to laugh and cry about the same as I did, but it seemed like I could never really know what somebody else was thinking.

      The reasonableness of skepticism is indeed so obvious that even a child can grasp it.

    2. FYP, The reasonableness of Santa Claus is indeed so obvious that even a child can grasp it.

    3. The internet needs to invent a sarcasm font.

    4. Also FYP means fixed your post. Joke is officially dead now. She will be missed.

    5. Oh. Don't interact with Stardust guy, he's just a word multiplier.

    6. Don,
      The reasonableness of Santa Claus is indeed so obvious that even a child can grasp it."
      Indeed, which is why we all knew Santa Claus is not real. Obviously, all those guys at the malls could not all be Santa Claus, there is only ice and the Arctic Ocean at the North Pole, and besides, we didn't even have a fireplace chimney.

      We didn't really believe in Santa Claus as kids, it was obviously just a fun little game during present receiving season.

      Chesterton, in his typically pointless bloviating way, spoke of what may be asked by a child, not what all children must ask.

      The reasonableness of skepticism when applied to the Jesus death story, Santa Claus, and whether we can know other minds, is so obvious that a child may understand.

    7. Folks, please don't feed the StardustyPsyche troll.

    8. "Indeed, which is why we all knew Santa Claus is not real."

      WTF bro! How about a heads up for the kids out there.

    9. We didn't really believe in Santa Claus as kids, it was obviously just a fun little game during present receiving season.

      Thanks a lot. I'm sobbing on my smartphone.

    10. Don,
      Nah, I'm no Grinch, I still sign the package "Santa". Dad will always be Santa, I look more an more like him every year!

    11. @StardustyPsyche

      I really did believe in Santa as a child. It was never "playing along" for me. I remember the confusion also when I was walking in ny hallway and realized the whole story wasn't logical.

      But I always hated clowns and my first experience crying for emotional reasons was because of a jack-in-the-box.

    12. Uhm, Balanced, you are breakin my heart here! To be fair, the word "child" is pretty ambiguous, I only used it unqualified as a response to the Chesterton quote. Maybe when I was five or something, dunno, but dude, all those different Santas in different stores, I mean, hopefully you figured it out before your 18th birthday, I'm pretty sure you did.

      More to the point of the OP, even kids can be skeptical and wonder if other people are really thinking the same things we are thinking. Plus, even if kids are not typically reading deep philosophical material there were a few good TV shows like Star Trek with alien computers in a battle of wits with Captain Kirk to inspire some skeptical thoughts about what a mind is and if a computer could have a mind and if it did how would we know the computer was really thinking and feeling like us, not just putting out words to mimic our words?

    13. Chesterton certainly wasn't immune to bloviation. And his claim about sceptical philosophers certainly is blovious. And of course black pots often don't fear to point out the bloviation of black kettles, although perhaps they should.

    14. Children ask good questions. It's a shame when they're given stupid answers. It's a greater shame when they hang on to those stupid answers for the rest of their lives.

  9. Anyone here read Edith Stein's dissertation "On the problem of Empathy"? It's not really about empathy as we understand it, but more about how we perceive other minds and interact with them in particular ways. We don't just point out their existence, but sometimes seem to share experiences that go beyond mere observation. (Or, at least, that is what I remember from having tried to read it a while back). It seems to treat on this very issue from a phenomenological perspective, but does so in a way that I find more interesting. And since I saw much of modern philosophers listed here, I figured it would be worth noting.

    Unfortunately, I was only able to get through the first few pages because I'm not really trained at all in phenomenology (or any philosophy for that matter).

    1. Yes, excellent point! There is an interview of Donald Wallenfang I heard recently on . . . I think it's called "Curious Catholic Podcast" regarding Edith Stein and empathy. You may want to check it out. Empathy is a little different question than the existence of other minds (the former assumes the latter), but it is certainly relevant. I think there is something on "The Thomistic Institute" on this as well (I'm away right now so I can't look it up). I'm pretty sure I saw something there on this. Check that out as well.

    2. I read some stuff by Saint Edith Stein a few years ago and it was all very, very good. She is very underrated as a philosopher. I need to familiarize myself more but I could see a gold mine there. Same with SJPII's philosophical work, influenced by similar lines - you'd think the English translation to the saintly pope's main philosophical book would be easy to find, but it isn't.

    3. Veritatis Splendor is just a masterpiece, but it's more "traditional" and less Phenomenological than JPII’s other works. “Love and Responsibility” (1960) is the gold standard for JPII’s personalism IMO, but it is a difficult read. I’ve read it twice and I still don’t get it. Honestly, I find it very difficult to read Phenomenologists. They say everything six ways from Sunday. It reminds me of a friend who tells his wife she should tell her stories backward so she can get right to the point. Ha! Phenomenology is like contemplative philosophy, and I don’t think I’ve been given the grace.

      Edith Stein is an amazing figure. The force of her character alone wins her credibility, and that touches on something integral for Phenomenology right there. The dry arguments for other minds are one thing, the experience is another. The difference is as stark as the description of the world by math equations vs. the experience of qualia, and the Phenomenologist has taken on the difficulty of engaging the latter. The physicists tell us they’re going to capture everything in an equation, but that’s completely wrongheaded. The end isn’t math; the end is contemplation.

  10. "How do I know that any minds at all exist other than my own?"

    From the weight of their ... gaze.

  11. I think, try as one might, one must conceive of Cartesian doubt as a good tool for epistemic processes. Perhaps not a truth tracking one, but a good one nonetheless