Common Sense: A Contemporary Defense By Noah Lemos Cambridge: Cambridge University Press, 2004. pp. xvi + 192. Lemos offers no arguments in this book for the claim that common sense beliefs are known. There are no arguments for the claim that there are external objects, including other people, and that all of us know a great deal about the world and ourselves. Is there a need for argument? Have a look and you will see that you have hands. The external world is, after all, hard to miss. Cast your mind back, and you will find that you remember all sorts of things. You know that you have been around for a while, and in that time you have come to know about the world and the things in it. You know quite a bit, and you know the same is true of me and other people, too. For the common sense philosopher such facts are data, assumed for the purposes of philosophical enquiry. Arguing for them is beside the point. An almost audible flinch accompanies these sorts of reflections, for some philosophers anyway. There are good sceptical arguments going back to Sextus and Agrippa which render problematic not just our knowledge of external objects and other minds but the general reliability of our faculties of sense and memory. Even if you are unmoved by scepticism, you might think that knowing cannot be as easy as the common sense philosopher maintains. At the very least, epistemology consists in something other than assuming that we know what we seem to know. The enterprise has to do with examining and arguing for certain views of the nature, extent and conditions of knowledge. The almost audible flinch can turn into audible objections, and Lemos s aim in this book is to deal with some of them. The book begins with a chapter on the basic
tenets of the common sense tradition, with particular attention paid to saying why common sense propositions should be taken as data. Lemos maintains that such propositions enjoy a positive epistemic status they are things we are justified in believing, and that is why they are data. Once the common sense philosopher starts talking justification, a number of objections arise. Some objections have to do with reliability and circularity. Lemos takes the critic of common sense to argue as follows. Knowledge based on perception and memory depends upon knowing that memory and perception are reliable. The only way to show this is via a non-circular argument, an argument that does not depend on the reliability of memory and sense perception. The common sense philosopher has no such argument. Lemos maintains that this line of thinking depends on two assumptions: (A1) Knowledge based on perception and memory requires that one know that perception and memory are reliable; and (A2) the only satisfactory way to know that perception and memory are reliable is on the basis of a non-circular argument. A1, Lemos argues, might be supported by the view that perceptual and mnemonic knowledge are inferential, but Lemos maintains that such knowledge is cognitively spontaneous. There is no inference behind my belief that there is coffee in the cup. I just look in the cup and get the belief. A1 might be supported by some version of what Chisholm calls the generalizability thesis : to know p you also have to know that beliefs formed in the way you formed p are themselves reliable and that p really was formed in this way. Lemos follows Chisholm in thinking that the thesis is too strong. It ought to be rejected on the grounds that it leads to a kind of general
scepticism, requiring an infinite chain of two-part justifications for any proposition. Finally, one might support A1 with talk of epistemic irresponsibility. If one has no justification for the meta-belief that one s belief p is reliably formed, one is epistemically irresponsible in holding p, and irresponsibly held beliefs are not knowledge. Lemos argues, flatly, that knowledge does not require responsibly formed beliefs. Children and animals know things, he says, but they might not have the meta-beliefs required for epistemic responsibility. You might be flinching again. The replies given in Lemos s treatment of A1 are of a piece with the rest of the book: his responses depend on the sort of premises the critic of common sense probably would not accept in the first place. A sceptic about the justification of perceptual knowledge is not going to be impressed by the possibility that perceptual beliefs themselves are formed non-inferentially. What is at issue is not just how the beliefs were formed, but what justifies us in thinking them true. Maybe the beliefs are formed non-inferentially, but what is needed is a justification for the beliefs, an argument, and justifications of this kind are inferential. The fact that the generalizability thesis leads to scepticism is not a reason for the sceptic to reject it. And who says children and animals really know anything? The flinching might stop once you recognize that this book is a defence of the common sense tradition from within the common sense tradition. It is an attempt to show that common sense philosophy has the resources to cope, from within and on its own terms, with various objections. Consider Lemos s treatment of A2 and the charge of epistemic circularity. Here he joins Sosa in accepting a Neo-Moorean argument for the reliability of
perception, which runs as follows. I know here is a hand. Seeing that here is a hand is the only or best way to account for my knowledge that here is a hand. Perception explains how I know here is a hand. However, perception could not be a source of knowledge if it were not reliable. So perception is reliable. The argument is circular it is in virtue of the conclusion (perception is reliable) that we know the first premise (here is a hand) but Lemos argues that, nevertheless, the argument really does give us a reason to think perception is reliable. A chapter is devoted to spelling out all of this by responding to attacks on Sosa in the writings of Fumerton and Vogel. When Lemos gets down to business, arguing point by point with detractors, the book really does bring the common sense position into clear view. Lemos is faithful to text and uses a fair bit of quotation which does aid the reader, but there are moments when he might be too involved with a particular philosopher s version of an objection, rather than the point of the objection itself. Fumerton, for example, points to the sense in which one could never satisfy a distinctly philosophical curiosity about the reliability of sense perception by using sense perception to justify the reliability of sense perception. Lemos notes, rightly, that Fumerton elsewhere uses acquaintance in his effort to justify his belief that he is acquainted with things, properties, and relations. Fumerton, therefore, cannot consistently object to the common sense philosopher s use of sense perception to justify his belief in the reliability of sense perception. Well, maybe that is true, but if you do not share Fumerton s views on acquaintance, his objection still stands. The common sense philosopher s views on reliability are further clarified with an instructive chapter on Reid, largely devoted to squaring Reid s criticism of
Descartes with certain parts of the common sense view. In the first part of the chapter, Lemos argues that Reid rejects A2, the claim that the only satisfactory way to know that perception and memory are reliable is on the basis of a non-circular argument. He considers Reid s view that our knowledge of the reliability of our faculties is itself immediate and therefore not something known on the basis of argument, as well as what looks like Reid s version of the Neo-Moorean argument for reliability. There is a kind of tension, here and elsewhere in the book, when we find Lemos or another common sense philosopher arguing that no argument is required for reliability and then, a moment later, unselfconsciously offering an argument for reliability. Lemos is aware of this tension, and claims that such arguments might somehow enhance beliefs already known, render them better known, contribute to a reflective believer s understanding of knowledge. It is not clear that the tension really goes away in the end. Consider the well-trodden ground of philosophical reflection on headaches. Suppose I know I have a headache, and I know this non-inferentially. My understanding of this knowledge is not enhanced if you point out that an inference can be drawn from the facts that I only take pain killers when I have a headache and that I just took some to the conclusion that I do have a headache. If something really is known non-inferentially, can an inference render it better known? Is my knowledge of the headache enhanced in any way at all? A few more words about the point of such arguments might help. The obligatory chapter on Moore s proof of the external world (here s a hand; here s another; therefore there are external objects) goes some way towards bringing
the debate up to date. There is a consideration of not just the usual charge of question-begging, but a treatment of Stroud s criticisms, as well as a consideration of challengers to Moore s anti-sceptical crown in the form of the relevant alternative and contextualist replies to scepticism. Here, Lemos works through several senses in which it might be thought that Moore s proof begs the question. Lemos notes that Moore s proof does beg the question, if we interpret him as supposing that his perceptual knowledge of here s a hand depends on both the reliability of sense perception and the existence of the external world. However, Lemos takes the view that Moore might suppose instead that his knowledge of here s a hand is immediate, non-inferential. Begging the question is an error of inference, and if there is no inference then there is no such error. Moore himself is not much help here. In Proof of An External World, he does call his proof a proof ; he talks about his premises being different from his conclusion; and throughout he seems to be talking about an inference. In Hume s Theory Examined, though, he claims that his knowledge of here s a pencil is known immediately. You can make matters worse for yourself by recalling that in A Defence of Common Sense Moore claims that we know many things but admits that we do not know how we know them, suggesting that proof is not always to the point. Lemos might be forgiven for plumping for the version of Moore he thinks best copes with the objection. A chapter on Chisholm deals with the problem of the criterion. Chisholm asks two questions. What do we know? What criteria can we use to pick out instances of knowledge? A particularlist thinks we can answer the first question and use our
answer to make progress on the second. However, some philosophers, methodists, argue that this is to get things the wrong way around. One cannot answer the first question without an answer to the second, without some criteria in hand. Sceptics, of course, argue that one cannot answer either question without simply assuming an answer to the other. The chapter, you might have guessed, argues against methodism and defends particularlism against a number of objections in the recent literature. Two final chapters take up the common sense view of a priori and ethical propositions. The chapters will seem to some a little tangential to the project of defending common sense philosophy from its largest objections, but they are interesting in their own right. Anyway, the book is profitably viewed as an explication of the common sense tradition from within, not just a defence of common sense, despite the sub-title. If regarded in this way the inclusion of the chapters is fitting. This book will certainly not free you from your reverie, if you are stuck in Hume s chamber and troubled by scepticism. If you are already outside a common sense philosopher enjoying the fresh air then this is a book which you will find reassuring. If you are somewhere in the middle, as perhaps most of us are, then the book is worth reading if you are after an account of common sense philosophy as a common sense philosopher understands it. James Garvey