The Refutation of Rationalism

I am back from my vacation in Liberty City 🙂

Seriously though, gta 4 is a lot of fun and very addictive!

I have recently been very interested in showing that rationalism is hopeless. To be open, I confess that I used to be a rationalist when I was younger. When I first started studying philosophy I was very influenced by Descartes and found his talk of clear and distinct ideas and ‘the light of nature’ very compelling. There is no suprise here, as rationalism has been the dominant view in the Western tradition since its inception. But, as rationalists like Bonjour admit, rationalism has suffered several notorious and embarrassing setbacks. Perhaps the first of which goes back to Gallileo showing empirically that Aristotle’s physics was wrong in assuming that heaverier bodies fall faster than lighter bodies. More dramtically, perhaps, is the discovery of non-Euclidean geometry which showed that various of the fundamental postulates of geometry were not necessary (like the parralel postulate). We should perhaps add to this the discovery of Russell’s paradox and the various self-referential semantic/syntactic problems (i.e. Godel, the liar, etc) which have led to the development of alternative logics.

What this shows is that intellectual seemings are fallible. It cannot therefore be argued that something seeming to need no empirical support and seeming to be justified purely by reason is enough to establish that the fact in question is really justified independently of experience or not. So, take 1+1=2. It certainly seems that this is true, in fact it is hard for me to imagine how it could be otherwise. There is a strong subjective sense of certainty that I experience when I think about it. All of this is no doubt true. But we have as of yet no reason to think that it is REALLY necessary, or that its justification is independant of experience. This is because we can not tell a priori whether the intelectual seeming is indeed correct. This shows that rationalism is in serious trouble. There is no other reason to take rationalism seriously other than the strong pull these rational insights have on us.

One might want to reply by saying that is overly skeptical. We shouldn’t abandon a priori knowledge just because we have mistakenly identified somethings as necessary which weren’t. So too, the objector goes on, just because we hallucinate doesn’t mean that we don’t normally see objects. Fair enough. But then what we need is an actual account to back this up. What is the difference between the cases? We can give that in the empirical case. We can describe ways in which we could find out whether the person was hallucinating or not based on our ability to monitor the brain of the animal in question and our visual impressions of the experimental set up. We can give a sketch, if not every detail, of a story which desribes how the brain interacts with the enviornment it finds itself in and generates representations of that environment. But can you do the same for rationalism? To date no one has. What is an eternal, necessary, non-physical/non-natural object like a number or modus ponens really like? How do we interact with it? No one knows. How could they?

Now this would be a pressing concern if it were impossible for us to fully understand the world we live in except for the truth of rationalism. But this certainly isn’t the case. We have good candidates for materialistic accounts of every disputed area. For instance, in the area I know most about, we have the mind-brain identity theory and the higher-order theory of consciousness. I do not mean to say that we know that they are true, but only that they are viable candidates. For all we know right know they could be true. They have not been absolutely refuted by any a priori arguments, nor have they shown themselves to be inconsistent with the findings of science, quite the converse actually. As for math and logic we have either constructivism or Mill’s view that they are empirical generalizations (I interpret this to mean that they are an attempt to model the way that the physical world works and to grow into Quine’s indispensibility argument that the justification for mathematic is empirical), or a more modern version of deflationism or fictionalism about this stuff. The same is true for ethics.

Again, none of these has been demonstrated to be correct. The point, rather, is that we should prefer natuaristic/materialistic accounts ove their non-natural/non-physical competitors. They automatically become more plausible because of their reliance on the more plausible empiricist/scientific account of knowing.

19 thoughts on “The Refutation of Rationalism

  1. What is an eternal, necessary, non-physical/non-natural object like a number or modus ponens really like? How do we interact with it? No one knows. How could they?

    Well, I suppose the questions to start with, since your argument presupposes that we have answers to them, would really be, “What is a changing, contingent, physical/natural object like a cat or a black hole really like? How do we interact with it? And, since there certainly are people who have insisted that nobody knows how we interact with anything, how can we know that we interact with it?”

  2. What would be the reason to think that non-euclidean geometries are not a priori? As the rest of the math, they are not done by any other means but a priori thought.
    In fact, many mathematical theorems found practical use, only after they being perfectly finished within the mathematics. So, it is not as if they were waiting for empirical confirmation.
    The issue was if this or that mathematical model was suited for this or that real world phenomenon.

    As for the question of abstract notions which are used in a priori reasoning as numbers, there is no need for a rationalist to seem them as objects of some kind. To me, more it is about the possibility for real things to fall under those notions, not about those notions independently existing.

    So to say, a bunch of objects might be a pair, or a triplet. And whenever it is a pair, it is one and one more object. So, the a priori conclusion there, that whenever there is a pair, there is one and one more object, has nothing to do with special kinds of objects.

    That is at least how I see rationalism. Not giving truths about some mystical objects, but giving general, “if A is X, then A is Y” kind of statements.

    In practical sense, when those notions approach the categories we CAN approach in life, like space, time, movement, and so on, sure, empirical confirmation is best method, because as you pointed even rationalist can admit that our reason is fallible, and might oversee or misunderstand things. But, given the rationalist can accept the need for empirical confirmation, I don’t think the situation for rationalists is as bleak as you think it is.

  3. Concerning Gallileo, Euclid, and Russell, I agree with the following sentiment.

    “What this shows is that intellectual seemings are fallible.”

    But it does not follow that the only alternative to the Cartesian rationalist tradition is one which treats revision of intuition as an empirical matter. There are rationalists out there today like Bealer who admit the fallibility of intuition, so I don’t see how this is meant to weigh in favor of empiricism.

  4. Hi Guys, thanks for the comments. Sorry I have been slow in getting back to you, gta sucked me back in for a minute…


    Here is what Devitt says in his ‘No Place for the A Priori’ paper

    what is the empirical method of justification? An answer starts from the metaphysical assumption that the worldly fact that p would make the belief that p true. The empirical justification of the belief is then to be found in its relationship to experiences that the worldly fact would cause. Justified beliefs are produced and/or sustained by experiences in a way that is appropriately sensitive to the way the world is. This is very brief…Still it is hard to say much more.

    This sounds about right to me. The claim is that even in this brief and sletchy form it is still light years ahead of anything that the rationalist has every come up with.


    The answer to your question is given by physics and biology. Sure it is not complete, there are many unanswered questions and debate still rages at the forefront. All standard stuff. But still we can give quite a bit of detail about the cat, and the blackhole for that matter, using the empirical method of knowing sketched above. We interact with these physical objects just like all physical onjects interact, in ways described by physics, and biology. Can anything like this be done for non-physical eternal objects?


    If that is all you mean by a priori then we don’t really disagree. The problem was that people claimed that Euclidean geometry was necessary and universal, which is to say that it couldn’t possibly turn out to be false and it was true everywhere. This was supposed to be know on the basis of rational insight to be a necessary fact about reality. So, the discovery of non-Euclidean geometry is a huge embarrasment. So, the question is not so much one of what it is that we know (as you suggest), but rather what is the justification for what we know? The kind of knowledge you point out ‘If A is X then A is Y’ could be justified by experience, in which case it is not a priori in the sense that I am arguing against.


    The problem is supposed to be the following. Given that intuition is fallible the rationalist needs to provide some way to discrimintae between cases where it is correct and cases where it isn’t. No such discriminatory method has ever been given. So, since it’s fallible, and we can’t tell when it works and when it doesn’t, it doesn’t provide any support for the existence of another kind of knowing that is distict from the empirical way of knowing. But the main (and only) motiviation for rationalism is the existence of rational insight and its pull on us. So unless the rationalist has some kind of story to tell that makes their view at least as non-mysterious as the empirical onbe sketched above the fallibalism counts against them.

  5. The answer to your question is given by physics and biology. Sure it is not complete, there are many unanswered questions and debate still rages at the forefront. All standard stuff. But still we can give quite a bit of detail about the cat, and the blackhole for that matter, using the empirical method of knowing sketched above. We interact with these physical objects just like all physical onjects interact, in ways described by physics, and biology. Can anything like this be done for non-physical eternal objects?

    This response won’t work, as far as I can see; for one, the rationalist will deny that you can get the detail using the empirical method you suggest, without presupposing rationalist principles; I am going to have to bring up complaints about your refutation of rationalism similar to ones I brought up about your default argument if your ‘refutation of rationalism’ depends so crucially on rationalists already being wrong.

    But more importantly, obviously we can do something like this for mathematical objects (you keep returning to ‘non-physical eternal objects’, and as I’ve said before this presumes more than it should, since not all rationalists are committed to such things, as opposed to, say, non-empirical features of physical objects): it’s called mathematics, and last I heard it was a pretty rigorous field of inquiry, one presupposed extensively in physics.

  6. Richard, I think the problem you raise for fallibilistic rationalism in your response to Colin, if legitimate, applies just as much to empiricism. Consider the following paraphrase:

    “Given that sense perception and / or empirical methods are fallible the empiricist needs to provide some way to discriminate between cases where it is correct and cases where it isn’t. No such discriminatory method has ever been given. So, since it’s fallible, and we can’t tell when it works and when it doesn’t, it doesn’t provide any support for the existence of another kind of knowing that is distinct from the rational way of knowing.”

    No one, whether rationalist or empiricist, is in a position to leap outside of their own minds and directly compare their beliefs with reality. Really, the problem is just the old skeptical one of how we can be sure, once we admit that *any* purported source of knowledge is fallible, that it is giving us the correct result in some particular case. In the present case, to use sense perception and / or empirical methods to justify themselves is circular, and an appeal to rational intuition is something an empiricist cannot accept. If we grant we are nevertheless justified (for whatever reason) in trusting sense perception and empirical methods, why not grant the same concerning rational intuition?

  7. Brandon: Mathematics is neutral as between rationalism and empiricism. So you can’t just appeal to mathematics as evidence of a well worked out rationalist theory. The rationalista nd the empiricist can agree about all of the truths of mathematics; what is at issue is whether they are necessary or contingent, universal or local, justified by experience or by reason…and the very fact that math is presupposed by physics is the basis of an argument for its empirical justification…

    And what rationalist principles do I have to assume to explain the biology of the cat?

    btw, what is a ‘non-empirical feature of objects’? I mean, seriously, what is that?


    Thanks for the comment. I don’t think that the parralell holds. For we can, via the empirical method, determine when our experience ‘misrepresents’. True, there are issue about global skepticism, and I think those are real issues. But you cannot use rational intuition to correct rational intuition.

    Also, we are not using the empirical method in a circular way. The argument is that when you have the two theories layed out side by side a plausible meta principle dictates that we go for the empirical. So, we are justified in accepting the empirical method, and not the rationalist method, because of their track records, both by their own standards and comparatively…

  8. “But you cannot use rational intuition to correct rational intuition.”

    But that is exactly when mathematicians do when they point to a mistake in a proof of some theorem. They don’t make special arrangements in the reality, in order to empirically justify the theory – instead they go through the steps and try to figure out if there was something wrong with the thinking of the other person.

    “and the very fact that math is presupposed by physics is the basis of an argument for its empirical justification”

    Why would a possibility to apply some mathematical model count as justification of that model. Would that mean that any mathematical model which can’t be applied is unjustified? Then if it is not empirical justification, what is the justification of mathematical theorems and model which found ‘use” in physics only subsequently to their being finished in the math?
    Anyway, it seems to me that what is justified by experience is that this or that mathematical model is applicable to this or that phenomenon. The experience can’t give justification for the model itself. How would that work?

  9. Mathematics is neutral as between rationalism and empiricism.

    This is not something rationalists would, or should, concede; the strongest rationalist arguments have usually been the difficulties of adequately accounting for various fruitful mathematical fields on purely empiricist principles, and what you are expecting here is that rationalists pretend (because for most rationalists it would be pretending, since they don’t believe it) that empiricists really are the equals of rationalists in an area that rationalists have always regarded as the area in which they especially shine. So, again, it seems to me that this is just an example of refuting rationalism on the assumption that rationalism is false, namely, on the point that empiricism has limitations that it can’t overcome.

    That physics presupposes mathematics is an empirical justification, yes, in the sense that physics has an empirical side; but there is nothing particularly empiricist about empirical justifications. This is particularly true in the case of physics since the rationalist will take the dependence of physics on mathematics as an indication that physics, certainly a field a reasonable empiricist cannot ignore, is already shot through with rationalism.

    A common argument (although perhaps not universal) among rationalists is that you cannot on empiricist principles have an adequate account of function; in other words, function is a non-empirical feature of physical objects that cannot be adequately cashed out under empiricist assumptions. Since the biology of cats will involve, in part, investigation of physiological functions, tsuch a rationalist would regard it as requiring rationalist principles. This is one reason why you cannot simply assume that a field like biology is empiricist in a refutation of rationalism.

  10. Hey guys, sorry I haven’t been getting to this sooner…I have been real busy preparing for my dissertation defense…finishing up my dissertation and trying to get people to agree to be at some place all at the same time! Very hard!!



    I am not sure why you think checking a proof involves anything a priori. Sure, you can check to make sure that someone has followed the rules of math or logic and so check to see whether a proof is accurate or not. The question at hand though is what we are to make of the rules and outcome of the proof.

    The point I was trying to make was that if I have a rational intuition that the law of non-contradiction, or principle of suffiecient reason, or whatever, is a fundamental, necessary fact about reality and yet I know that rational intuitions can be fallible, I cannot use rational intuition to tell whether or not this particular intuition is correct or not. You haven’t suggested anything that poses a problem for this claim.

    You ask, “Why would a possibility to apply some mathematical model count as justification of that model. “ The problem is this. If physics aims to describe the world that we live in then that it holds is a contingent fact aboout reality. This is why lots of philosophers think that the laws of physics could have been other than they are, or that there are possible worlds where there are different laws of physics. But since we are unable to do physics without mathematics we have reason to think that mathematics is confirmed empirically. This follows from Quine’s kind of holism.

    You then ask “Would that mean that any mathematical model which can’t be applied is unjustified?” The answer is ‘yes’. According to this view theonlyreason that mathematics is interesting is because it is applicable to the natural world. The justification for those kinds of theorems which seem theoretical only is to be found in the general usefulness of mathematics itself combined with our having learned that sometimes there are new and novel applications of mathematical results thatare not immediately obvious. So we can justify even obscure work in mathematics on this basis, but if it were not the case that mathematics had any relevance to the natural world then there would be no reason to be interested in it as a science.

    “The experience can’t give justification for the model itself. How would that work?”

    I am not sure how to take this…it would work in the way that the empiricists says that it does…that is that the worldly fact that p would be responsible for our experience that p and the justification is to be found in the relation that holds between the experience of p and p.


    I understand what you are trying to say. I see the way you are looking at the problem. From the rationalists’ point of view only their theory can give a satisfying account of certain mathematical facts. No doubt this is exactly what they say. The empiricists say that there is a problem with rationalism, the problem being that it does not meet empiricist standards. Your argument is that the rationalist should not be held to empiricist standards, or at least that they will not be moved by an argument which tries to show that they do not meet empiricist standards. I agree that a lot of debate (on both sides) amounts to this: Assume that your theory is false, then your theory is false. So, your theory is false.

    But this is not what I am trying to do here. Rather the point is that philosophical issues in mathematics are hard. No one has a good theory of the epistemology of mathematics (the argument of the previous posts was that starting from this position and chossing which theory to adopt we should do so by adopting the simplests and best understood theory which is empiricism). One thing that we can say though is that whether there are numbers or not 2+2=4 will still be true. Whether 2+2=4 is a necessary fact about reality or not it will still be true. It is not as though, if empiricism is right then there are no mathematical truths! (the case of fictionalism is a bit tricky). What changes is WHY it is true and HOW we know that it is true (e.g. because it is analytic, or because it is an empirical generalization). In this respect mathematics is neutral. You say that the rationalist should not admit this, but why isn’t that question begging? What argument is there that if numbers aren’t non-physical objects then it is false that 2+2=4? If it is because you have a theory of reference according to which ‘2’ names an object then you need an argument that the object it names is non-physical. Just assuming that it must name a non-physical object is question begging in the worst sense. Now, of course, the empiricist is committed to the claim that it is possible that it is false.

    I did not know that about function. Thanks for the information. Do you have any particular philosopher in mind?

    There are several good naturalistic candidates for funtion. There is Millikan, Cummins, and others, perhaps newer stuff like Craven’s work on mechanisms. I would be very interested to know what why rationalists think we can’t give a proper account of function on empiricists’ scruples!

    If physics can be confirmed empirically then it can be disconfirmed empirically.

  11. It seems to me that the distinction between the rational and the empirical is not so well defined as it is often made out to be. On one hand, I don’t think that philosophers can do armchair metaphysics like the Moderns did (including and especially Kant!). Of course, I am not up on all the current debates, but I’ve read virtually no metaphysican who thinks this (but I don’t read much epistemology). On the other hand, it’s difficult for me to understand what a purely empirical philosophy might be like. It seems to me that it would have to be something like ‘the buck stops here’ stand point. More technically, we might say that whatever supposed ‘a priori truths’ that are ‘discovered’ they are always subject to potential falsification (thus essentially mooting the idea of an a prior all together). I don’t think mathematics can hold the kind of ground that those camp of rationalists suppose when they throw mathematics out as their paradigm. Its just too fuzzy there to convince someone who is not already a believer. But, and this is the punchline, all empirical evidence to support inductive hypothesis are already interpreted! And they are interpreted in some way. This is where I see the vague boundary between the empirical and the rational. We can take physics as our paradigm. I don’t think that because physics employs mathematics (implies) that somehow mathematics (as arguably a priori) demonstrates that rationalism, in its stone cold classical version, is true. But I take it that no natural science is presuppositionless. Of course, our perspective on our presuppositions can become more sophisticated – but nonetheless. Even is we assume that there is something like a purely sensual – I just ‘look’ at the phenomenon and try and ‘tell it like it is’ it is already — must be — comprehended within some context. And, this context is a rational context (in that in its most minimal, it is ‘interpretable’). On the flip side, I am willing to concede that such contexts very well may be epistemological (I even debate this regarding bivalence); but as far as human knowledge and a coherent world view is concerned – It’s difficult to see what a refutation of rationalism could really be.

  12. Hi Trey, thanks for the comment.

    I am not sure if I am reading you right. Is your point that since al empirical knowledge has to be interpreted in the context of some theory it is therefore indeterminate what pure empirical knowledge looks like?

  13. Idealism, in my mind, can only work if one is simply going to argue “You don’t REALLY know what the world ‘God’ means. This is to say that we are talking about the skeptical side which contains a pretty nice proof for God, we are not talking about the denial of the material world. Those debates seem to be as above mentioned the product of semantics and the imperfections of language. In actuality, Idealism does not reject sensations wholly, merely the fact that external sensations produce the true knowledge of the world. Instead, idealists hold that there is no true knowledge. Because there would by necessity have to be false knowledge. This can’t happen in idealism because the same rational concept of God cannot exist and cease to exist at the same time. One cannot truly perceive God, he perceives us. This is what makes idealism work… but using only logic and no external sensation one can conclude that God would have to perceive himself to also exist. The Greatest Possible Being, who exists because without which everything else would cease to exist, REQUIRES the logical contradiction of omnipotence. Empiricism makes no such absurd claim. Omnipotence is the only way the Greatest Possible Being could have complete understanding of what itself truly is, and omnipotence can’t work. If you believe that it does that you have stopped using reason and have lost the argument.
    Plus “ideas” are just another way of saying “internal sense” and idealism could just be called internal sensationalism or something.

  14. John S. but using only logic and no external sensation one can conclude that God would have to perceive himself to also exist.

    Isn’t there a counter-example to that statement in the ordinary experience of awareness? I know that I am aware because I am aware, but there is nothing I can perceive that is aware. If I examine my awareness for the object that is aware, I cannot find it.

    To maybe make this a little more clear, consider a dream. The “me” in my dream is just an object within the dream, but that object has no awareness. The dream exists within awareness but nothing within the dream manifests awareness. If you believe in materialism, it is the waking “me” that is aware, not the “me” I perceive within my dream.

    In the waking world I am in the same situation, the objects within my awareness are a collection of sensations in the same way that dream objects are. The sensations are not aware, rather I am aware of them.

    The dream world is an example, I think, of Richard Brown’s “Zoombie” world. Everything and everyone within the Zoombie world has all of the non-material aspects of waking creatures, but they lack non-material consciousness. They also (being merely dreamed objects) lack any physical reality. And, as Richard Brown correctly points out, the Zoombie argument shows that consciousness doesn’t arise from any of these non-material aspects.

    The big advantage of idealism, in my view, is that (in contrast to materialism) it works even in created worlds such as computer simulations and dreams. No special pleading is involved.

    If we were to create an artificial intelligence, it is certain that its awareness would be of the internal logical model within the operation of that computer program. We might be able to arrange for that logical model to correspond to a real external world, but there would be no way for the AI to know whether it was modeling a real world or a simulation.

    Idealism doesn’t necessarily reject the real world, it only rejects that the abstract models we create from knowledge of our sensations are necessarily true knowledge of the world (and you said something very similar to this). In that sense, Idealism is simply a more general approach.

    Maybe, by analogy with Brown’s Reverse-Zombie argument against dualism, we could says that there are Type A and Type B idealists, depending on whether matter is held to be manifestly inconceivable or whether there is an illusion that it is conceivable.

    If you don’t start from the assumption of materialism, which is that our mathematical abstractions correspond to a reality of substance that is divisible and impersonal, then what can you say about existence? That is the question that idealism seeks to answer.

    My view of this is very practical. Simulated worlds are no longer exceptional, and in every case the simulated world can be seen to conform to the idealistic view, the appearance of substance within the world is always merely an appearance and never the reality. We can point to myriad virtual worlds and see that idealism works and that materialism is refuted.

    Materialism requires special pleading, and totally unnecessary special pleading, for the one world that we cannot see “from the outside”. It is a philosophy whose conclusions fail to follow from its axioms in every one of the innumerable cases where it can be tested.

  15. I just glanced upon this and it seems its turned into a language issue and how lack of communication (even with technology) is causing people to loose true meaning of what they are actually talking about.

    but ,if i may, my argument against rationalism is just that you cannot develop a swaying argument using reason as your only method of gaining knowledge. I mean to even assure ourselves that 2+2=4 we use sense preception not reason and upon using sense preception we generalize that everytime we add 2 and 2 we get 4. although this is not a hasty generalization it is still a generalization so we can never be sure that every time we add 2 and 2 we will get four. Even if we are some how able to add 2 and 2 an infinite amount of times we still do not neccessarily know the outcome if we do it 1+infinity times and so on.

    for clarification my definition of a rationalist is one who constitutes reason without any other ways of knowing and believes it is the most important way of knowing.

    if i made a mistake anywhere please correct me im just begining to study epistemology and only in high school 😉

  16. and may i ask why plato and etc are looked upon so highly?
    i know they had “great” minds but i honestly dont think they did anything that anyone couldn’t do today

  17. Hi Talha, keep up the good work!

    Maybe Plato etc didn’t do anything that we couldn’t have done today, but they did it first. And, whats more, they seemed to have thought of about everything that could be said on almost every topic! That’s pretty amazing…

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