Common Sense, Philosophy, and Science

Noah Lemos

Some philosophers have held some rarher startling views, views that run contrary to common sense. Among the ancients, for example, we find philosophers such as Zeno claiming that nothing moves, that all motion is an illusion. Other ancients declared that we do, in fact, know nothing. Perception, reason, and memory, they tell us, are simply incapable of yielding knowledge. In the modern age, we find Bishop Berkeley concluding from his philosophical principles that the only things that exist are immaterial minds and their ideas. Berkeley thus denies the existence of material objects and of a mind-independent reality. David Hume has followed Berkeley’s principles even further, arguing that we know nothing of material objects but also that we cannot know anything about the future or the past, other minds, or even that there is an enduring self, a thinking, perceiving self, that persists over time. For some philosophers, if their philosophical principles lead to a conflict with common sense, so much the worse for common sense.

In opposition to this attitude, other philosophers have sided with common sense. The 18th-century philosopher Thomas Reid, a contemporary of Hume, held that that the conclusions of Berkeley and Reid were indeed contrary to our common sense beliefs, yet Reid held that these common sense beliefs were of greater weight and authority than the conclusions drawn by Berkeley and Hume and of greater weight and authority than the philosophical premises and assumptions from which they were drawn. Reid claimed that if their principles and conclusions were incompatible with these common sense beliefs, then we should abandon them in favor of our common sense beliefs. Reid is one of the earliest and most well-known members of what has become known as ‘the common sense tradition’ in philosophy, a tradition that includes the 20th-century philosophers, G. E. Moore and Roderick Chisholm. It is characteristic of the common sense tradition to take common sense beliefs as data for philosophical reflection and reject those philosophical views that conflict with them.

A. C. Ewing was sympathetic to the common sense tradition in philosophy. Nevertheless, in a paper on common sense propositions, he asks why philosophers should be expected to pay so much respect to common sense. Why, he asks, should those who have studied philosophy alter their philosophical views because people who have never studied it think them wrong? What, he asks, would happen to the natural sciences if scientists had been forbidden to contradict the views that nonscientists held on scientific matters before they had studied science? He replies, “We should still be believing in a flat earth with the sun and all the stars going round it if people acted on those lines”.[1]

Essentially, the objection assumes that because it would be a mistake to reject scientific views that conflict with common sense beliefs, it would also be a mistake to reject philosophical views that do so.

But is this so? What role should our common sense beliefs have in philosophical or scientific inquiry? Should they have any weight at all? And, if so, why?

Moreover, what if scientific views do conflict with common sense beliefs? Suppose we concede that some common sense beliefs cannot be reasonably sustained in the face of scientific evidence; what are we to think when some scientists tell us that there are no publicaly observable objects or that given the theory of evolution we have no good reason to think that our moral beliefs or perceptual beliefs are likely to be true? Challenges to our common sense beliefs are not confined simply to philosophers.

In this essay, I want to explain and defend the common sense tradition. I fear that much of what I say will be much too cursory, and I can only say in my defense that I have tried to address some of these issues at greater length elsewhere.[2] In any event, I consider in the first section some main features of the common sense tradition. I consider briefly what it is for something to be a common sense belief and the scope of our common sense beliefs. I also note some views to which the common sense tradition is not committed. In the second section, I ask why any of our common sense beliefs should have the weight that members of the tradition take them to have. I will examine briefly three sorts of answers to this question. In the third section, I reply to some objections philosophers have raised against the appeal to our common sense beliefs. In the final section, I make some comments about the relationship between our scientific beliefs and some common sense beliefs. I note that some cases of apparent conflict between science and common sense are in fact conflicts between common sense beliefs and philosophical assumptions held by some philosophers and scientists.

understand the notion of a common sense belief differently, but I shall take a common sense belief to be either (i) a belief in a proposition that is deeply held by almost everyone or (ii) the self-attribution of a property that almost everyone attributes to him- or herself. Thus, the belief that there are other people is a common sense belief because it is the belief in a proposition that is deeply held by almost everyone. Similarly, my belief that I have a body is a common sense belief because it is the selfattribution of a property, the property of having a body, which almost everyone attributes to him- or herself. Other examples of common sense beliefs would be the belief that people think and feel, that they were born, and that they existed yesterday and my beliefs that I have hands, that I am alive, and that I was much smaller when I was born.

What is the scope of our common sense beliefs? There are a great many common sense beliefs, and I am certain that I can’t list them all. Nevertheless, in addition to the examples just mentioned, they include epistemic claims. They include beliefs such as these: most people know that they have bodies, most people know that there are other people who think and feel, I know that I have body, I know that I have hands, and I know that I am alive. Almost everyone accepts the epistemic propositions that most people know they have bodies, and most people know that there are other people who think and feel. More generally, almost everyone accepts the proposition that people have knowledge. Similarly, almost everyone attributes to him- or herself the property of knowing that he or she has hands, knowing that he or she has a body, and knowing that he or she is alive.

In addition to epistemic beliefs, there are also common sense beliefs about our own faculties. These include the beliefs that our memories, under certain conditions, are reliable; that perception, under certain conditions, is reliable; and that introspection, under certain conditions, is reliable. These principles about our faculties, or ones very similar to them, are what Reid calls ‘first principles of common sense’. They may not be consciously formulated, but they are accepted nonetheless. They guide our belief formation and the way we assess the testimony of others.

I believe, then, that the scope of our common sense beliefs is quite large and includes epistemic beliefs and beliefs about our own faculties. I think it likely that it also includes some moral beliefs, perhaps the beliefs that some actions are right and some actions are wrong and that some things are good or bad or better than others. Perhaps it also includes beliefs that what we do is sometimes up to us, that sometimes we could have done otherwise, and that there is a God.

In any event, we can distinguish two views concerning common sense beliefs an extreme view (EC) and a moderate view (MC):

EC: All common sense beliefs are true.

MC: Some common sense beliefs are true.

I would say that some common sense beliefs are obviously true. Thus, it seems to me that MC is true. But what about ЕС? I, myself, see no reason to accept EC. EC seems to me no more reasonable than the claims that all scientific beliefs are true or all philosophical beliefs are true. We know such claims about scientific and philosophical beliefs are false, and there is no good reason to suppose that common sense beliefs fare any better in this regard than they do.

Moreover, many philosophers in the common sense tradition who accept MC would not endorse EC. G. E. Moore, for example, in his “A Defense of Common Sense”, writes:

[t]he phrases ‘Common Sense view of the world’ or ‘Common Sense beliefs’ (as used by philosophers) are, of course, extraordinarily vague; and for all I know, there may be many propositions which may be properly called features in ‘the Common Sense view of the world’ or ‘Common Sense beliefs’, which are not true, and which deserve to be mentioned with the contempt with which some philosophers speak of‘Common Sense beliefs’. But to speak with contempt of ‘Common Sense beliefs’ which I have mentioned is quite certainly the height of absurdity. And there are, of course, enormous numbers of other features in ‘the Common Sense view of the world’ which, if these are true, are quite certainly true too: e.g. that there have lived on the surface of the earth not only human beings, but also many different species of plants and animals.3

Moore’s defense of common sense beliefs is clearly limited. Although he holds that some common sense beliefs are true and instances of knowledge, he is not committed to the view that all such beliefs are.

If I am right about the scope of common sense beliefs, then to hold that no common sense beliefs are true, to accept not-MC, is to embrace a form of skepticism. This is because it is a common sense belief that people do, in fact, have knowledge. To hold that no common sense beliefs are true, and that this particular common sense belief is not true, is to accept the skeptical view that it is false that people know things. To hold that no common sense beliefs are true is to imply that there is no knowledge and, thus, no scientific knowledge.

Moreover, to hold that no common sense beliefs are true is to deny that perception and memory are, under certain conditions, reliable. But if it were false that perception and memory are sometimes reliable, then it is hard to see how there could be any scientific knowledge at all. It seems to me, therefore, it is reasonable to hold that there is scientific knowledge only if one accepts MC, that some common sense beliefs are true.

Furthermore, most of what anyone knows about science is based on the testimony of others. Scientific knowledge is the result of the collaborative efforts of large numbers of people who make use of the testimony of others. It is hard to see how one could coherently hold that we have scientific knowledge based on the testimony of others and deny the common sense claims that there are other people who think and know things. It would be like saying, “I know that Paris is in France because John told me so, but I have no idea whether John knows that, or anything at all, or even if he exists”.

Philosophers in the common sense tradition accept not only MC, but they also accept this:

MCK: Some common sense beliefs are instances of knowledge.

Some common sense beliefs, such as the beliefs that there are other people, that they think and feel, that I have a body, and that I know that I am alive are instances of knowledge. Not only are they true, but we know them to be true.

To accept MCK does not commit one to holding that there is a sui generis ‘faculty of common sense’ or that we know common sense propositions on the basis of such a faculty. Such a view is simply not to be found in Moore or Chisholm. Reid, of course, does refer to a faculty of common sense. It is not clear, however, that Reid considers it to be a sui generis faculty. Indeed, he suggests that “common sense” is “only another name for one branch or degree of reason”.4

Moreover, in holding that some common sense beliefs are instances of knowledge, we are not committed to the view that they are known in virtue of their being common sense beliefs or in virtue of their being deeply and widely held. We are not committed to the view that being deeply and widely held confers, or is a source of, any positive epistemic status on a proposition.

But how do we know such things? What makes a common sense belief an instance of knowledge? Indeed, what makes any belief knowledge? Those, of course, are important epistemological questions. They are, however, far beyond the scope of this paper. I shall confine myself to making two general points.

First, there are significant differences among the members of the common sense tradition such as Reid, Moore, and Chisholm concerning the nature of our knowledge of the external world, the past, and other minds. They have different epistemological views about how we know such things. But they would agree that one need not know how one knows such things to know them. They would say, for example, that I can know there are other people, and know that I do, without knowing how I do and certainly without having a well-developed theory about how such knowledge is to be had. Moore writes, “We are all, I think, in this strange position that we do know many things, with regard to which, we know further that we must have had evidence for them, and yet we do not know how we know them, i.e. we do not know what the evidence was”.5

Second, the fact that some propositions are a matter of common knowledge is not without significance. If almost everyone has knowledge that there are other people, that they think and feel and know things, then there must be some way of knowing these things that does not rest on philosophical arguments or considerations grasped only by a handful of philosophers, and it can’t be the fruit of philosophical reasoning followed only by a philosophical elite. Whatever our account of knowledge, it must be adequate to the fact that such knowledge is widespread and common.

2 What Gives Some Common Sense Beliefs Their Weight?

In describing the common sense tradition, Chisholm writes, “It is characteristic of ‘commonsensism’, as an alternative philosophical tradition, to assume that we do know, pretty much, those things we think we know, and having identified this knowledge, to trace it back to its sources and formulate criteria that will set it off from things we do not know”.6 We may say that the common sense tradition holds that we do know many of the things we ordinarily take ourselves to know, and our philosophical views should be adequate to the fact that we do know them. It holds that we may use much of what we take ourselves to know as data for developing and assessing philosophical theories and principles.

Reid, too, takes such a stance. Reid took Hume’s empiricism to imply that we have no knowledge of the material world; no knowledge of the future, the past, or other minds; and no knowledge of ourselves as continuing subjects of experience. Reid took Hume to show that the wages of empiricism are a rather thoroughgoing skepticism. Reid writes:

[a] traveller of good judgment may mistake his way, and be unawares led into a wrong track; and while the road is fair before him, he may go on without suspicion and be followed by others but, when it ends in a coal pit, it requires no great judgment to know he hath gone wrong, nor perhaps to find out what misled him.7

Reid held that because we do know many of the things that Hume’s empiricism would rule out, so much the worse for empiricism.

We also find a similar theme throughout Moore’s writings. In his 1919 essay, “Some Judgments of Perception”, Moore begins by considering some views about perception and the possibility of perceptual knowledge. He rejects certain philosophical views because they imply that we cannot know facts about the external world:

[b] ut it seems to me a sufficient refutation of such views as these, simply to point to cases in which we do know such things. This, after all, you know, really is a finger: there is no doubt about it: I know it, and you all know it. And I think we may safely challenge any philosopher ro bring forward any argument in favour either of the proposition that we do not know it, or of the proposition that it is not true, which does not at some point rest upon some premiss which is, beyond comparison, less certain, than is the proposition which it is designed to attack.8

Again, Chisholm takes a similar stance:

[w]e reject the sceptical view according to which there is no reason to believe the premises of an inductive argument ever confer evidence upon the conclusion. If the skeptical view were true, then we would know next to nothing about the world around us.9

Chisholm holds that because we do know a lot about the world around us, so much the worse for skepticism about induction.

But why should we take common sense beliefs as data and reject philosophical theories that clash with them? What gives these beliefs such weight? I would like to consider three sorts of answers defenders of common sense have sometimes offered.

The first answer is suggested by Chisholm. He writes that in investigating the theory of knowledge from a philosophical point of view, we assume that what we know is pretty much that, which on reflection, we think we know. He goes on to say, “This might seem like the wrong place to start. But where else could we start”?

As a defense of the common sense tradition, this does not seem compelling. Surely, there are alternatives one could adopt. One could, for example, follow a Cartesian model and confine one’s data to what is certain and indubitable, or one could confine one’s data to propositions about one’s own mental states. One cannot plausibly defend the common sense tradition on the grounds that it is the only approach available.

A second answer can be found in the following striking passage from Reid’s Inquiry:

[t]o what purpose is it for philosophy to decide against common sense in this or any other matter? The belief in a material world is older, and of more authority, than any of the principles of philosophy. It declines the tribunal of reason, and laughs at the artillery of the logician. It retains its sovereign authority in spite of all the edicts of philosophy, and reason itself must stoop to its orders. Even those philosophers who have disowned the authority of our notions of an external world, confess that they find themselves under a necessity of submitting to their power.

Methinks, therefore, it were better to make a virtue of necessity; and, since we cannot get rid of the vulgar notion and belief of an external world, to reconcile our reason to it as well as we can; for, if

Reason should stomach and fret ever so much at this yoke, she cannot throw it off; if she will not be the servant of Common Sense, she must be her slave.10

Reid claims that the belief in the material world is irresistible. He counsels us to “make a virtue of necessity”; because we can’t get rid of certain common sense beliefs, such as a belief in the existence of a material world, we should make our philosophical views fit these deeply held beliefs. Indeed, Reid often points to the difficulty of giving up certain sorts of beliefs and to the futility of skeptical arguments. In explaining why he does not ignore the testimony of his senses in the face of skeptical arguments, Reid says, “[B]ecause it is not in my power; why then should I make a vain attempt? ... My belief is carried along by perception, as irresistibly as my body by the earth”.11 Here again Reid seems to be defending common sense beliefs on the basis of their irresistibility.

The appeal to irresistibility, however, does not seem to be a satisfactory way of defending the common sense tradition. First, why would the irresistibility of such beliefs matter for assessing philosophical theories? The fact that a belief is irresistible might be an excuse for holding it, but it is not a good reason for holding it, and it would not be a good reason for rejecting other beliefs that conflict with it. Consider a bad habit that one cannot give up, such as smoking or overeating. Surely, one should not abandon one’s belief that such habits are unworthy of being indulged simply because one cannot give them up. It would be unreasonable to change one’s beliefs about the value of one’s habits simply because of a conflict between one’s beliefs and one’s deeply rooted habit. Why, then, should one abandon one’s philosophical beliefs simply because they conflict with beliefs that one cannot give up?

Second, perhaps many common sense beliefs are irresistible. Perhaps this is true of beliefs such as there are bodies and there are other people, but as we have seen, the common sense philosopher also takes as data epistemic propositions, such as I know that I have a body and almost everyone knows that there are other people. But is it really clear that these epistemic propositions cannot be given up? Could one not hold, for example, “Yes, I have a body. I cannot give up that belief. But it isn’t something I know. Maybe it’s more likely than not, but I don’t know it”. It is not clear that all the propositions that common sense philosophers would take as data are irresistible. So, it is not clear that the common sense philosopher should point to irresistibility as what makes it reasonable for him or her to take common sense propositions as data.12

A third answer to the question “Why should some of our common sense beliefs have such weight?” is what I call the epistemic answer. According to this approach they have such weight because they are instances of knowledge and more reasonable to believe than the philosophical principles that conflict with them. The common sense philosopher may thus point to the positive epistemic status of the beliefs he or she takes as data. Reid, Moore, and Chisholm all hold that they know common sense propositions and that almost everyone knows them. Thus, Moore says he knows that this is a finger and that this proposition is more reasonable, and more certain, than the premises of skeptical arguments that imply that it is false. Similarly, Chisholm writes in defense of his theory of knowledge and his commonsensism, that “it corresponds with what we do know”.13 Reid, also, in the passage cited refers to the ‘authority’ of our belief in the material world. Indeed, he tells us that it has more authority than any of the principles of philosophy. The concept of ‘authority’ is a normative notion, and Reid is making a normative claim about such beliefs. He is not merely claiming that the belief in the material world is more firmly held, that it is irresistible, but that it is also worthy of being more firmly held, that it is more reasonable to believe.

Here, then, we have a reply to Ewing’s question why philosophers should be expected to pay so much respect to common sense. It is because some common sense beliefs are instances of knowledge and they are more reasonable than the philosophical principles that compete with them.

In his defense of Moore and the common sense tradition, William Lycan makes a similar point. Lycan claims that all skeptical arguments rest on some abstract metaphysical or epistemological principle that is doubtful:

[j]ust as there is no such thing as an idealist argument that does not appeal to some metaphysical or epistemological principle that is simply assumed without defense, there is no such thing as a skeptical argument that does not do the same thing. Which is to say that there is no good reason to accept the argument-, the unargued principle is only philosophy stuff.14

Lycan also claims, “No purely philosophical premise can ever (legitimately) have as strong a claim to our allegiance as can a humble common-sense proposition such as Moore’s autobiographical ones”.15 And again, “A metaphysician who claims to ‘just know’ that such an abstract principle is true (‘This is a deep intuition’) cannot be taken seriously”.16

Consider the following skeptical argument, one Moore himself entertained:

  • 1 If I don’t know that I am not dreaming, then I don’t know that I have hands.
  • 2 I don’t know that I am not dreaming.
  • 3 Therefore, I do not know that I have hands.

Why should we think (1) is true? What supports that premise? Perhaps the skeptic will support (1) by appealing to some ‘principle of exclusion (PE)’, such as one of the following:

  • (PE) One knows that p only if one can rule our (know to be false) any proposition q that one knows to be incompatible with one’s knowing that p.
  • (PE’) One knows that p only if one can rule out (know to be false) any proposition q that is relevant to one’s knowing p and that one knows to be incompatible with one’s knowing that p.
  • (PE”) One knows thar p only if one can show to be false any proposition one knows to be incompatible with one’s knowing that p.
  • (PE’”) One knows that p only if one can rule out (know to be false) any proposition one knows to be incompatible with p.

Are any of these principles of exclusion as reasonable to believe as I know I am standing up or I know I have hands? Surely, the answer is no.

Something similar may be said concerning the second premise of the argument. How might the skeptic support premise (2)? Skeptics have appealed to principles such as the following:

  • (El) One knows that p only if one’s evidence for p logically implies that p is true.
  • (E2) If A’s evidence for p is not better than B’s evidence for q and A does not know p, then В does not know q.
  • (E3) One knows that p only if one’s belief that p is sensitive. (One’s belief that p is sensitive just in case if p were false, one would not believe that p.)

Again, are any of these principles as reasonable to believe as “I know have hands” or “I know that this is a finger”? Again, the answer is surely no.

Still, we must be careful not to overstate this position. Lycan says that no purely philosophical proposition can ever legitimately have as strong a claim to our allegiance as can a humble common sense proposition. But that does not seem quite right. The proposition that if S knows that p, then p, seems to be a philosophical proposition as reasonable to believe as many common sense propositions, including Moore’s autobiographical ones.17 Indeed, it might be more reasonable to believe than some common sense propositions. Philosophical propositions, like common sense propositions, can vary in their reasonableness. Moore need not claim that no philosophical proposition is as reasonable as his common sense claims. He need only hold that the common sense claims he appeals to are more reasonable than one or more of the philosophical propositions that underlie skeptical arguments.

Still, we may wonder why the Moorean knowledge claims are more reasonable than the philosophical propositions. Of course, Moore might note that whereas it would be desirable to have an explanation for their greater reasonableness, we need not have such an explanation for them to be more reasonable or for us to know that they are. A satisfactory epistemological account of what makes one sort of belief more reasonable than another is not necessary for us to know, in some cases, that they are more reasonable.

It is open, however, to Moore and other defenders of common sense to appeal to a familiar array of views to explain the greater reasonableness of his common sense claims over the competing philosophical principles. He might hold that we are more reliable about the former, that we are simply more reliable about whether we know that we have hands than we are about the sort of abstract philosophical principles to which the skeptic appeals. Alternatively, he may hold that the former cohere better with the rest of our beliefs. He might point to such factors or a combination of them to explain why his common sense beliefs are more reasonable.

Consider coherence. Which coheres better with one’s total body of beliefs, the proposition that I know I have hands or some philosophical principle, such as PE” or E2? One’s total body of beliefs will include things such as I have hands, almost all human beings have hands, I am very good at identifying hands and other human appendages, almost everyone knows that he and others have hands, I see that I have hands, perception under the present conditions is highly reliable, and I and others know much about the world around us. If we wonder which coheres better with our total body of beliefs, can there be any serious doubt that it would be the Moorean common sense epistemic claims rather the philosophical propositions that underlie the skeptical argument?

Of course, it might be held that reasonable belief requires more than coherence. Perhaps it will be urged that reasonable belief concerning p requires also that we be reliable with respect to p. But even if this were so, is there any good reason to think that the Moorean knowledge claims would fare worse? Moore may plausibly hold that we are far more reliable about humble epistemic propositions such as “I know this is a finger” than about the abstract philosophical principles underlying the skeptical arguments. About the former almost everyone is a competent judge, and there is much agreement. About the latter it is not clear that we are competent judges, and there is little agreement.

3 Philosophical Objections to the Common Sense


The common sense tradition has faced a variety of objections. Sometimes it is objected that common sense beliefs can be false and unreasonable. Consider the following criticism:

[ijntuitive and common-sense judgments can be false, as a little reflection illustrates. Such judgments, furthermore, seem not always to be supported by the best available evidence. Consider, for instance, how various judgments of “common sense” are at odds with our best available evidence from the sciences or even from ordinary perception.18

Perhaps some common sense beliefs are epistemically shoddy, but there is no reason to think that is true of the particular common sense beliefs to which Moore, Chisholm, and Reid appeal. But as I have noted, philosophers in the common sense tradition need not endorse everything that might be properly called a common sense belief. As we have seen, Moore does not claim that all common sense beliefs are true or justified. If there are good reasons for rejecting some common sense beliefs because they are ‘not supported by the best available evidence’ or at odds with ‘our best available evidence from the sciences or even from ordinary perception’, there is no reason whatsoever to reject Moore’s claims that I know this is a finger or I know that there are other people on such grounds. Those particular claims don’t suffer from such defects.

As we have seen, philosophers in the common sense tradition hold that they can pick out particular instances of knowledge and justification. Critics of commonsensism sometimes raise questions about the epistemic status of our particular epistemic judgments:

[i]t is often left unclear what the epistemic status of the relevant pre- analytic epistemic data is supposed to be. Such data, we hear, are accessed by “intuitions” or by “common sense”. We thus have some epistemologists talking as follows: “Intuitively (or commonsensi- cally), justification resides in a particular case like this and does not reside in a case like that". A statement of this sort aims to guide our formation of a notion of justification or at least a general explanatory principle concerning justification. A simple question arises: is such a statement self-justifying, with no need of independent epistemic support? If so, what notion of self-justification can sanction the deliverances of intuition or common sense, but exclude spontaneous judgments no better, epistemically, than mere prejudice or guesswork?19

This passage suggests that the common sense tradition holds that epistemic facts are accessed via ‘intuition’ or ‘common sense’. If this means that the common sense tradition holds that we know epistemic facts on the basis of a faculty of common sense or intuition, as we know about the past on the basis of memory, then there is no good reason to accept this claim. There is no good reason to think that Moore or Chisholm holds such a view. Although one might be able to make a stronger case that this is Reid’s view, it is not clear that this is his view either. Moreover, the commonsensist need not hold that particular epistemic judgments such as I know this is a finger are self-justifying. He might hold that particular epistemic judgments are justified in virtue of their cohering with one’s other beliefs, or because they are the product of a reliable cognitive faculty or intellectual virtue, or because they are appropriately related to what is given in experience. There are many candidates for sources of justification besides self-justification.

Of course, what makes particular epistemic beliefs justified is an important problem for epistemology. But, as we have seen, Moore distinguishes knowing that some proposition is true from knowing how we know it or what makes it an instance of knowledge. Moore also holds that one can have the former sort of knowledge without the latter. Such a view seems plausible. Consider our knowledge of evaluative properties such as the beauty of a piece of music or the wrongness of an action. One might know that a particular piece of music is beautiful or that an act is wrong without knowing what makes it so. I might know, for example, that it would be wrong for me to kill my secretary now without knowing what makes it so. I might not know whether it is wrong because it fails to maximize utility or fails to treat her as an end or for some other reason. In any case, the common sense philosopher may agree that it is unclear what justifies our particular epistemic beliefs without denying that they are justified. Even if our particular epistemic judgments are problematic in the sense that we do not have a satisfactory explanation of what makes them justified, we need not deny that we know they are justified.

Another objection often leveled against the common sense tradition is that it is question-begging. As we have seen, the common sense philosopher holds that skepticism implies that we know nothing about the external world, but because we know a great deal about the external world, for example, that this is a finger, skepticism is false. Such a reply is sometimes said to be question-begging insofar as it takes as a premise the very point that the skeptic is denying. When one takes as a premise a proposition that is denied by one’s philosophical opponent, one’s argument is not going to be persuasive. Indeed, one’s argument seems pointless. Again, consider the following objection by Moser:

[qjuestions under dispute in a philosophical context cannot attract non-question-begging answers from the mere presumption of correctness of a disputed answer. If we allow such question-begging in general, we can support any disputed position we prefer. Simply beg the key question in any dispute regarding the preferred position. Given that strategy, argument becomes superfluous in the way circular argument is typically pointless. Question-begging strategies promote an undesirable arbitrariness in philosophical debate. They are thus rationally inconclusive relative to the questions under dispute.20

But here I think we should make three points. First, sometimes the point of an argument is not so much to persuade another person; it is rather to present (even if only to oneself) one’s reasons for believing something.

The common sense philosopher might argue against the skeptic in his or characteristic way even if he or she knows that such reasoning will not settle the dispute or convince the skeptic to abandon his or her view. If this is so, then the common sense philosopher’s response to the skeptic is not pointless. It displays his or her reasons for rejecting skepticism.

Second, even if an argument or a line of reasoning will not convince someone who doubts one of the premises, it might be nonetheless a cogent argument and one that provides one with reasons for believing the conclusion. Thus, if a detective asks suspect A why he or she believes that В is the killer, A might reply, “I know that the killer is either В or me. I know that I did not do it. Therefore, В is the killer”. Imagine that A knows every premise of his or her argument. A might know that В is the killer on the basis of such an argument. In presenting his or her argument, he or she displays sound cogent reasoning to the detective. Still, his or her argument might not convince the detective, who has no reason yet to exclude A. It might be rationally unpersuasive to the detective. Nevertheless, A’s argument is cogent and rationally conclusive in the sense that it gives him or her reason to accept the conclusion.

Third, not to make use of what one knows in philosophical inquiries seems poor intellectual procedure. In trying to get to the truth in philosophical inquiry, one should use all one’s evidence. One’s evidence includes those things that we know, and this includes a great many common sense beliefs and humble Moorean propositions; for example, this is a finger, I know this is a finger, and so do others. Not to make use of one’s evidence is poor intellectual procedure and intellectually irresponsible. The common sense philosopher’s procedure in rejecting skeptical arguments because they conflict with what he or she knows is good intellectual procedure even if it begs the question against the skeptical or some other philosophical view.21

Of course, one might engage in some inquiry and confine one’s evidence to that which is certain and infallible. Perhaps such a restriction might be justified if one seeks truth and is especially averse to error. But we have seen how well that works out. Or perhaps one wants to pursue inquiry reasoning only from mutually accepted premises. Such a restriction might be justified on some grounds, perhaps a moral ground of conviviality or even mutual respect. What is admissible for evidence in inquiry can certainly be limited by moral or practical considerations, as in a trial where certain types of evidence are inadmissible. But it is not clear that that there are moral or practical reasons for not appealing to what we know in philosophical inquiries. One should search for the truth with both eyes open.

Let us consider one further objection raised by Laurence Bonjour:

to accept commonsense convictions as Moore and other particu- larists do, does appear to rule out illegitimately even the possibility that skepticism might in fact be true, that common sense might be mistaken. And, equally important, if this solution is taken at face value, it would have the effect of stifling or short-circuiting epistemological inquiry at least as effectively as would simply acquiescing to skepticism.22

Does the appeal to common sense as I have described it stifle epistemological inquiry? That depends on what one takes to be involved in epistemological inquiry. It does not seem to stifle the search for criteria of knowledge and justification. On the contrary, common sense philosophers such as Chisholm take the search for such criteria to be among the principle aims of epistemology. Even if we assume that we do know things about the world around us, we might wonder how we know them. We still might seek philosophical answers to that question.

Furthermore, the common sense philosopher need not ignore skeptical arguments or consider them idle. He may take skeptical arguments seriously, attempting to identify what plausible, yet mistaken, assumptions yield skeptical conclusions.

Bonjour also objects that the appeal to common sense appears to rule out illegitimately the possibility that skepticism is true. But here we should be careful. Does it rule out the possibility that skepticism is true? Not if the relevant sense of possibility is that of ‘logical possibility’. Common sense philosophers such as Chisholm, Moore, and Reid grant that it is logically possible that skepticism is true. They grant that it is logically possible that we are deceived by evil demons or dream experiences and know next to nothing about the world around us. Still, they would deny that skepticism is ‘epistemically possible’ in the sense that, given what we know, it is reasonable to believe that skepticism is true. They would hold that because we do know much about the external world, it is not reasonable to accept skepticism about the external world. But they would deny that this is to rule out skepticism illegitimately.23

4 Common Sense and Science

So far I have addressed the relationship between certain common sense beliefs and philosophical views. I turn now to consider briefly the relationship between scientific beliefs and certain common sense beliefs.

Some scientific propositions are more reasonable to believe than some propositions that were once deeply and widely held. It is more reasonable to believe that the earth orbits the sun, that the earth spins, and that the sun is bigger than the earth. I assume the negations of these claims were once widely and deeply held. The scientific evidence against these views is overwhelming.

At the same time there are a great many common sense beliefs that science has not shown to be false. These include many of the common sense beliefs mentioned above, for example, the beliefs that perception, memory, and introspection are, under certain conditions, reliable; that there are other people who think and feel; that we have bodies; and so forth.

Not only has science not shown such beliefs to be false, but they are known to be true. We have a great deal of evidence for them. Furthermore, there is no good reason to think that there will be scientific evidence that shows that such beliefs are false. Indeed, it is hard to see how one could have good scientific evidence for denying that perception and memory are reliable under certain conditions. Indeed, what scientific experiments could provide sufficient evidence to show that it is now false that there are other people who think and feel and have bodies?

Although science can show that certain deeply and widely held beliefs are mistaken, we must be on guard against claims that science conflicts with some common sense belief, when in reality, the conflict is actually between common sense and some philosophical view held by a scientist.

To illustrate my point, imagine a philosopher or scientist who holds that all that really exists are only space-time points and, therefore, the common sense belief that there other people who think and feel is false. Would such a view be supported by purely scientific evidence? I don’t think so. It seems to me that such a view would depend crucially on certain metaphysical views, for example, about the ontological status of complexes and their constituents. Such a view might tell us that the only things that really exist are the fundamental entities of physics. It would imply not only that there are no people but that there are no stars or planets, or molecules or elements, or animals or plants. It would imply that the subject matters of astronomy, chemistry, and biology do not exist. I think such a metaphysical view is false. It is, as Lycan says, “only philosophy stuff”. If the common sense philosopher rejects the view that only space-time points exist, he is not really rejecting a scientific claim; he is rejecting a metaphysical thesis and one that it is far less reasonable to believe than the proposition that there are other people.

Another sort of example involves not an imaginary philosopher but a real one. In an exchange with Ernest Nagel, Bertrand Russell writes,

Mr. Nagel asserts with a passion that he has seen tables, but he adds that he means this in the sense in which we ordinarily use the words “see” and “table”. I might agree if we take the phrase “see a table” as a whole.... My objection is that the phrase, as commonly understood,

involves false metaphysics.....What I see has secondary properties

recognized since Locke as not belonging to the physical object, and primary qualities concerning which the same has been recognized since Berkeley-or since Kant, by those who dislike Berkeley.

Common sense says: “I see a brown table”. It will agree to both the statements: “I see a table” and “I see something brown”. Since, according to physics tables have no colour, we must either (a) deny physics, or (b) deny rhar I see a table, or (c) deny that I see something brown. It is a painful choice; I have chosen (b), but (a) or (c) would lead to equal paradoxes”.24

Russell holds that the common sense view that one sees a brown table is mistaken, and he denies that he sees a table. We can take Russell to be arguing as follows: (1) I see something brown. (2) No table is brown. Therefore, (3) I do not see a table.

Why does Russell accept (2)? He gives two reasons. First, he appeals to the metaphysical view that colors are secondary properties that do not belong to physical objects. According to his understanding of this metaphysical doctrine, colors are properties of sense data or sensations.25 They are mind dependent. Second, Russell appeals to physics. He says that according to physics, tables have no color.

We have here an alleged example in which the common sense view that one sees brown tables conflicts with science. But is this really so? Russell appeals to the philosophical view that colors are properties of sense data or sensations to support his view that no table is brown. He also claims that this view is supported by physics.

Here I would make four points. First, г/the metaphysical view that Russell accepts is correct, then his premise that no table is brown is true. But, then, if the metaphysical thesis is true, his view does not need the support of physics. The metaphysical claim would suffice to support premise (2).

Second, it is far from clear, however, that his metaphysical view is correct. One might hold, correctly I think, that colors are properties of physical objects. Such is Reid’s view, who writes,

All people who have not been tutored by modern philosophy understand by color, not a sensation of the mind, which can have no existence when it is not perceived, but a quality or modification of bodies, which continues to be the same whether it is seen or not.26

On Reid’s view, the colors of things persist when they are not seen and do not go away when we turn out the lights. If this view of color is correct, and again, I believe it is, then Russell’s claim that no table is brown is false.

Third, which of these two views about color is correct? If the matter is a clash between two philosophical views about the nature of color, then it seems to me that the Russell’s philosophical thesis is less reasonable to believe than the claim that I see a table. The philosophical thesis that no physical object has color is less reasonable to believe than the claim that I see a table.

Finally, Russell claims that his view is supported by physics. I do not think that this is true. Does physics really support the claim that colors are properties of sense data or sensations over the claim that they are properties of physical objects? What experimental evidence from physics supports the one claim over the other? No doubt there are physicists and other scientists who have accepted the same metaphysical doctrine as Russell, but that does not show that there is scientific evidence that supports the one view over the other. The view is found, as Russell notes, in Locke, Berkeley, and Kant. But those illustrious thinkers present no evidence from physics or any actual scientific evidence that supports it.

Even Homer nods, and Russell followed his premises intrepidly to the coal pit. However, it was not science that paved the way but bad philosophy, or mere philosophy stuff, cloaked as science. Science can tell us a lot about our world. It can expand our knowledge and explain many things that are matters of common sense knowledge. It can tell us more precisely under what conditions perception and memory are reliable. It can tell us what properties in bodies cause us to have the sensations of color that we do. It can overturn beliefs deeply and widely held. But when it purports to do so, the wise person will ask whether it does so on the basis of weighty evidence or not and whether it does so on the basis of claims less reasonable than the common sense beliefs they are designed to attack.


  • 1. Ewing (1973, 367).
  • 2. Lemos (2004).
  • 3. Moore (1959, 33-34).
  • 4. Reid (1969, Essay VI, Chapter II, 567).
  • 5. Reid (1969, Essay VI, Chapter II, 45).
  • 6. Chisholm (1982,' 113).
  • 7. Reid (1983, 11).
  • 8. Moore (1960,228).
  • 9. Chisholm (1973,232).
  • 10. Reid (1983,4).
  • 11. Reid (1983, 85).
  • 12. For a more detailed discussion of the argument from irresistibility, Strawson- ian ‘naturalism’, and Wittgensteinian ‘hinge propositions’, see my Common Sense (Lemos 2004, 13-23).
  • 13. Chisholm (1977, 121).
  • 14. Lycan (2001,41).
  • 15. Lycan (2001,41).
  • 16. Lycan (2001,40).
  • 17. Earl Conee makes this point. See Conee (2001, 56).
  • 18. Moser (1998, 364).
  • 19. Moser (1998,363).
  • 20. Moser and vander Nat (1995,27).
  • 21. For an excellent discussion of these issues, see Kellv (2008). See also Lemos (2004, Chapter 1).
  • 22. Bonjour (2002, 265).
  • 23. For sympathetic and more detailed treatments of the common sense tradition’s response to skepticism, see Sosa (1999), Lycan (2001, 41), Lemos (forthcoming), and Lemos (2004).
  • 24. Russell (1973, 634-635).
  • 25. Russell takes the claim that colors are secondary qualities to imply that physical objects do not have colors. It is not clear that secondary qualities should be understood this way, and it is not clear that this is how Descartes and Locke understood them. Barry Maund writes, “Descartes and Locke, for example, think that there are no colors in the physical world—no colors, as we ordinarily and naively understand them to be. But they are also widely interpreted as holding a secondary quality view of colors, i.e., holding the view that colors are powers or dispositions to cause experiences of a certain type”. If secondary properties are understood as powers or dispositions of physical objects to produce certain sensations, then they are properties of physical objects. See Maund (2012).
  • 26. Reid (1983).


Bonjour, Laurence. 2002. Epistemology. Lanham: Rowman and Littlefield.

Chisholm, Roderick M. 1973. “On the Nature of Empirical Evidence.” In Empirical Knowledge: Readings from Contemporary Sources, edited by Roderick M. Chisholm and Robert J. Swartz, 224-249. Englewood Cliffs: Prentice-Hall.

Chisholm, Roderick M. 1977. Theory of Knowledge. 2nd ed. Englewood Cliffs: Prentice-Hall.

Chisholm, Roderick M. 1982. The Foundations of Knowing. Minneapolis: The University of Minnesota Press.

Conee, Earl. 2001. “Comments on Bill Lycan’s ‘Moore against the New Skeptics’.” Philosophical Studies 103 (1): 55-59.

Ewing, A. C. 1973. “Common Sense Propositions.” Philosophy 48: 363-379.

Kelly, Thomas. 2008. “Common Sense as Evidence: Against Revisionary Ontology and Skepticism.” Midwest Studies in Philosophy 32: 53-78.

Lemos, Noah. 2004. Common Sense: A Contemporary Defense. Cambridge: Cambridge University Press.

Lemos, Noah. Forthcoming. “Moore and Skepticism.” In The Oxford Handbook of Skepticism, edited by John Greco, 330-347. New York: Oxford University Press.

Lycan, William. 2001. “Moore against the New Skeptics.” Philosophical Studies 103 (1): 35-53.

Maund, Barry. 2012. “Color.” In The Stanford Encyclopedia of Philosophy (Winter), edited by Edward N. Zalta. entries/color/.

Moore, G. E. 1959. “A Defence of Common Sense.” In Philosophical Papers, by G. E. Moore, 32-59. London: George Allen and Unwin.

Moore, G. E. 1960. “Some Judgements of Perception.” In Philosophical Studies, by G. E. Moore, 220-252. London: Routledge and Kegan Paul.

Moser, Paul K. 1998. “Epistemological Fission: On Unity and Diversity in Epistemology.” The Monist 81 (3): 353-370.

Moser, Paul K., and Arnold vander Nat. 1995. Human Knowledge: Classical and Contemporary Approaches. Oxford: Oxford University Press.

Reid, Thomas. 1969. Essays on the Intellectual Powers of Man. Cambridge: MIT Press.

Reid, Thomas. 1983. Inquiry and Essays. Edited by Ronald E. Beanblossom and Keith Lehrer. Indianapolis: Hackett.

Russell, Bertrand. 1973. “A Reply to Ernest Nagel.” In A Modern Introduction to Philosophy, edited by Paul Edwards and Arthur Pap. 3rd ed. New York: The Free Press.

Sosa, Ernest. 1999. “How to Defeat Opposition to Moore.” In Philosophical Perspectives. Vol. 13, edited by James Tomberlin, 141-153. Cambridge: Blackwell.

3 How the Many Worlds

  • [1] Some Main Features of the Common Sense Tradition
  • [2] What is a common sense belief? I am not sure that there is any widelyaccepted answer to this question. I suspect the same is true for other sortsof beliefs, such as ‘scientific belief’ or ‘philosophical belief’. Others may
< Prev   CONTENTS   Source   Next >