Classics, Epistemology

In Book I of his traditionally-titled Against the Logicians (Book VII of Adversus Mathematicos), Sextus Empiricus presents a critique of how past philosophers have attempted to define the human being. He notes that these philosophers would pass off a definition as an “explanation of man” (132), a strategy that, for Sextus, would surely fail.

First is the account that goes back to Aristotle, though Sextus does not cite him directly. He remarks that some philosophers define man as a “‘rational, mortal animal receptive of thought and knowledge’” (132). Sextus points out that this does not conjure up man himself, but rather lists of some of his attributes.

With respect to attributes, Sextus says that there are two distinct types, those which are “inseparable” (132) from the thing which has them and others which “can be separated” (132) from the attributed object. Those which cannot be separated from the object include its extended dimensions, for an extended body is inconceivable without such attributes. Separated attributes, for Sextus, include activities or potential activities which an individual can take part in. For instance, speaking and sitting are attributes of the human being, since these are things which “happen to” people, “but not continuously” (132).

However, as Sextus states, neither the separable nor the inseparable attributes are identical to the thing that bears them. Hence, the Aristotelian definition fails to define the human being, since it only recounts some of humankind’s attributes: that human beings are animals, an inseparable attribute, and that human beings possess the separable attributes of “‘reasoning’ and ‘possessing knowledge’” (133).

For Sextus, the other component of the given definition, that human beings are mortal, is not an attribute at all. He remarks that mortality is not something that is ever an attribute of a human being, since what makes a human seemingly mortal, death, is never a part of the human but something that happens after the human ceases to exist. One is never at the same time human and dead, hence, humans do not have mortality as an attribute in Sextus’ language.

Sextus also makes the point that none of these attributes uniquely give us the idea of the human being. For instance, being rational or possessing knowledge are also attributes of the gods, while many animals exist besides human beings. Of course, such a definition does not mean to imply that each of these attributes are uniquely true of humans, rather, it is “all of them in conjunction” that present the human being.

To this, Sextus asks how these various attributes can be united to produce the human without also “exceeding” or “falling short” (134) of what human beings are. After all, human beings are not at all times rational or in possession of knowledge, nor do they possess mortality as an attribute because “death is not yet present” (134). So in this case, listing all of these attributes at any time may exclude some human beings, namely those who are not currently reasoning, possessing knowledge, or even simply still living. Hence, this definition exceeds that of human beings. Similarly, these are not the only attributes of human beings, so the definition in another sense falls short of producing the human.

The definition of man from Platonic sources also falls under Sextus’ scrutiny. He says that this definition describes man as a “‘featherless, two-footed, flat-nailed animal, receptive of political science’” (134). Such a definition fails to capture the human being for the same reasons as the Aristotelian one, namely that it gives a list of attributes, some of which are not constant in humans. Further, Sextus calls this definition “even worse than the others” (134) because it contains some negative attributes, such as ‘featherless’, along with positive ones, such as ‘twofooted’. That is, some of what is in this definitions are not attributes of humans, but an account of what are not human attributes.

Since no definition like those given can accurately capture the idea of human beings, or produce the “conception of particular men” (132), Sextus concludes that it is impossible to properly define the human being. Humans are, hence, left without a proper conception of themselves.

Sextus Empricius. Selections from the Major Writings on Scepticism, Man, & God. Ed. Philip P. Hallie. Trans. Sanford G. Etheridge. Indianapolis, IN: Hackett, 1985. pp. 132-134. #

Epistemology, Metaphysics

In Book I of On the Nature of Things[1], Lucretius provides arguments for the existence of two main things that exist: matter and the void. Further, he argues that there are no other types of things besides these.

First, Lucretius asserts that matter is known to exist by means of sensory perception. We see matter, we interact with it, and thus it must exist. He argues immediately for empiricism by saying that sensory perception must be the “unshakable foundation” (423) from which an epistemology begins. Otherwise, he says, any talk of what is unseen is meaningless, for it is only in contrast with sensory perception that we can reason about anything that is outside of our view. That is, we cannot make any sense of talk about what is hidden from view without having a view in the first place, and thus what we see in our view must be the case. So, matter exists.

Secondly, we observe some important traits about the matter we see. First, it is always situated somewhere. Second, it can be moved from one location to another. Both of these require the existence of space, what he calls the void, for things always move or are located in something. Lucretius refers back to a few lines before this passage[2], in which he has argued that without space existing between material objects, their force of obstruction would constantly be acting upon each other and there would never be movement at all. He also, in these earlier lines, anticipates an objection on the grounds that fish swim through water seemingly unobstructed. Here, Lucretius argues that water must give way and create space for the fish, thus in order for there to be movement the space must be ontologically present, in modern terms.

Next, Lucretius argues that there must be nothing else besides matter and void. His reasoning is simply that anything else that one may describe, in an effort to posit a third constituent of being, can be shown to be either matter or void. This is done by Lucretius by asking whether or not this new entity is tangible. If it is, and is “susceptible of even the lightest and faintest touch” (433), then it must add to the aggregate matter of the universe and thus count as matter itself. If it is not tangible, however, then it is nothing but “that empty space which we call void” (438). This amounts to the claim that everything exists is either tangible, and is therefore matter, for everything that is tangible is matter, or is intangible, and is therefore void, for everything that is intangible is empty space, that is, void.

Lucretius’ argument for the existence of matter is an ontological an epistemological argument, stating that matter must exist because we cannot meaningfully talk about anything besides matter without first admitting matter into our ontology. However, it is somewhat anthropocentric in its approach, since it relies on what human beings, or perhaps any sentient being, can talk about or count as existing, not what fundamentally exists independently. In this sense, Lucretius is merely categorizing entities into two groups, based on whether or not they are tangible. Since everything is either tangible or not tangible, due to the laws of non-contradiction and the excluded middle, everything can rightfully be said to fall into one of these two categories.

One can rightfully be sceptical of Lucretius’ claim that everything that is intangible is empty space. The tradition of philosophy before and after him posit many so-called intangible objects which are thought to be more than the void. Among them are the forms, or universals, which are thought by Plato to have greater reality than material things. Meanwhile, talk of God or gods both before and after Lucretius often involves an immaterial but certainly active being. Lucretius goes on, beyond this brief passage, to deny that anything can act upon matter without being corporeal[3], but more work must be done to overthrow alternative thought on this matter.

Yet, we can still praise Lucretius for a simple but elegant approach to two formidable views. The simple approach to an epistemological foundation predates the rampant empiricism of the modern era, and even reminds one of Quine‘s naturalized epistemology in its reductionist (and dismissive) approach. The view meanwhile that space counts as some entity in itself, and is needed for the situation and locomotion of matter is one common in modern science, if still debated. One can easily read contemporary developments into Lucretius’ ancient words.


[1] T. Lucretius Carus. On the Nature of Things. Trans. Martin Ferguson Smith. Indianapolis: Hackett, 2001. Lines 419-440.

[2] Lines 335-345 and 370-383.

[3] Lines 440-444. #


In the Pursuit of Truth[1], must one reify? Quine says that “substantial reification is theoretical” (25), beyond the simple observation sentences. We emerge from the “feature-placing” stage (24) and in the persistent recurrence of certain qualitative features we develop a theory that the set of features we regularly observe belong to some consistent, persistent object. These theories are purported to be useful. For the child it helps to recognize Mama as something other than the recurrence of Mama-features, if only for a sense of security. Endless metaphysical thought experiments have us imagining non-identical doubles of things we know, such as twin-Earths and doppelgangers, all with the impression that we’ll recognize that the identity of an object over time is important – seemingly identical objects with the same extension but different causes are purported to be non-identical.

Natural selection seems to have produced reification but is it truth proper to imagine the persistence of a single object between instances of its being observed? The question for the child is how much qualitative difference is acceptable between instances of Mama? If Mama changes her hair or her clothes, has cosmetic surgery or injures her vocal chords, will she still be recognizable as Mama to the child? She’s not strictly identical to the entire set of features previously observed. Observation sentences about her appearance will differ. The theory places her as the same object, but the stimulus meaning of “there’s Mama” has changed drastically since its last utterance. If “Mama” has changed enough, the child may not assent to the observation sentence.

This is where Quine later drew a distinction between perceptual and full reification. In a passage from a late manuscript cited by Peter Hylton in his text on Quine[2], by way of Leonardi and Santambrogio[3], Quine clarifies the terms:

Prior cognition of a recurrent body—a ball, or Mama, or Fido—is on par with our recognition of any qualitative recurrence: warmth, thunder, a cool breeze. So long as no sense is made of the distinction between its being the same ball and its being another like it, the reification of the ball is perceptual rather than full.

For Quine, the child is capable only of perceptual reification, rather than the full reification one that is present in a theory. I take this to be a sort of family resemblance between stimulus meanings. A child can recognize certain sets of stimuli that, in a criss-crossing mesh include various patterns that trigger recognition, representing something perceptually for that child even if the child lacks a theory of persons, minds, bodies or persistence of an object.

Hylton takes the question of reference to be “how we can get from observation sentences to a mastery of language that is clearly about particular entities”[4] My question is, in a world of bits where language refers to various arrangements of those bits, why must language be about entities in the strict sense? Why must we pass from the perceptual reification that occurs when those bits are arranged in familiar ways to the full reification that says that there is some entity there? It seems to me that we can preserve a tasty desert landscape without reification of anything beyond a fundamental bit. At the end of this chapter, Quine expresses his preparedness to bail on the traditional concept of existence (36). If existence can go by the board, the entity can follow.

I know I’m taking a step away from the point of this chapter when I zero in on this, and I had prepared a commentary on Quine’s indistinguishable, isomorphic ontologies but I read it over and wasn’t sure there was sense to any of it. Indeed we can build fairly successful theories with varying versions of the ontology. But I find the reification game a little superfluous, especially if we’re taking a behaviourist account of things. We can build our ontology around dogs, around sets of {dog} or their absolute complements like  ∁{dog}, and each adopt our own isomorphic ontology and I can talk about dogs meaning dogs, and Smith can talk about dogs meaning {dog} singletons and Jones can play around with his ∁{dog} complements – just as my red could be your blue and, I don’t know, maybe there’s magic. Perhaps I need to be reminded that reference even needs to be successful – why can’t it just be a game of resemblance and recognition? What seem to be entities over time swap out their bits with other bits and it barely matters if the bits are the same bits so long as whatever bits are there are behaving in similar ways. We’ll quickly assent to the same observations when the bits move around. Twin Earth is Earth or not Earth and, sure, XYZ can be water if you want it to be and now I sound like a pragmatist so I’ll fall just short of that and say that I don’t see a difference made.

We can all have our own brain-bits differently-arranged and equally assent to the same observation sentences and whenever we generally agree on the borders around sets of bits we’ll call it an entity. Or, better still, we’ll each list off all of the types of entities that we think actually exist as fundamental and with each one take a sip of scotch. Whoever is left standing wins.


[1] Quine, W. V.  Pursuit of Truth. Revised Edition. Cambridge, MA: Harvard University Press, 1992. Print.

[2] Hylton, Peter. Quine. New York: Routledge, 2007. §5, V.

[3] Leonardi, Paolo and Marco Santambrogio, eds. On Quine. Cambridge: Cambridge University Press, 1995). p. 350.

[4] Hylton. Quine. §5, V. #

Epistemology, Metaphysics, Philosophy

In his Mind and World, McDowell contrasts three positions in his concerns with spontaneity and intentional states in general. These are what he calls bald naturalism, rampant platonism and naturalized platonism, the last of which he defends. What McDowell calls ‘bald naturalism’ I will argue for, but I will refer to it more favourably, as ‘naturalism proper’.

The proper naturalist position counts the mind as part of the world, as McDowell wants to do. What a naturalist proper cannot coherently talk about is the Kantian subject. Instead, there are only objects. For those who would say that things are only objects in the sense that they are the object of some subject, then we may use the word ‘substance’, in the earlier Greek sense, to talk about physical things. Thus, the naturalist position is that everything is a substance; in Heidegger’s terminology, everything is essentially present-at-hand[1] and though further supposed properties or features of substances (readiness-to-hand, the existence of Dasein, the mind, intentionality, subjectivity) are reducible to that raw substance. In contemporary physics, that substance is identified with particles, though the details may be somewhat more complex than that[2]. The manifest image of the world[3], the normative space in which intentionality and morality are thought to lie, is composed of that same physical substance that makes up the brains of those who experience and project outwards.

So, for the naturalist proper, the space of reasons is not a realm outside of the natural or physical world, as it is in rampant platonism, nor is it an autonomous space within the world as it is in McDowell’s naturalized platonism. Rather, all rationality, normativity and intentionality is identical with brain states. There is no one space of reasons with which human beings have a connection; rather, each human being can be thought to have their own space of reasons. This space is not especially private, though. It can be seen physically by examination of the neurological states of the brain, and with the proper technology, those states may even be translatable into intelligible images. In another sense, it is not fully private, since glimpses into its content can be seen through behaviour.

‘Content’ needs qualification in that last remark. Intentional mental states are mental states that are about something else in the world. But they are neither a metaphysical link through some imaginary (or real) space to other substances which they are about, nor are they really representations of the substances they seem to be about. They are not the former because such space doesn’t exist in any important way. They are not the latter because, of course, the neurological features of our brain do not form a structure that mimics the outside world. Rather, they form a structure that allows us to have a mental state (which is identical with that brain state) such that we think we have a representation of the substance we are thinking about. So, when I close my eyes and picture the CN Tower, I do not obtain or summon some representation of that object. That object may be gone, moved, or different than I remember. Instead, my brain generates a certain arrangement such that it looks like the CN Tower to itself.[4] All of the qualia, ‘what it’s like to be’[5] and private world phenomena that philosophers expect to find in a separate mental world are  merely what the brain’s activity looks like from the point of view of that very brain.

Against the rampant platonist, the naturalist’s response is brief. Whatever attitudes one has towards the empirical observations with which one is presented, one does not survive without indulging in them. With a proper account of naturalism, any reason to favour a platonic account dissolves. Naturalism proper offers an explanation of intentionality, removes the “spookiness” (McDowell 92) of a separate space of reasons that McDowell complains of. We don’t need to add anything ontologically, and we have a hope to answer the how questions about mental states and intentionality through study of the brain. Spontaneity doesn’t need any explanation here, either, because it is not sui generis, if it’s counted as existing at all. We’re better off with the naturalist account.

Against McDowell’s naturalized platonism, the proper naturalist has to say that McDowell is wrong about naturalism. He argues against his ‘bald naturalist’, saying that “knowing one’s way around the space of reasons, the idea of responsiveness to rational relationships, cannot be reconstructed out of materials that are naturalistic” (McDowell 77). But the naturalist proper doesn’t want to reconstruct a space of reasons, really. The naturalist proper holds that all reasoning, all intentionality, all communication—the entire manifest image—takes place between physical substances across physical substances. The naturalist isn’t committed to reconstructing any intentional state beyond this because she doesn’t hold it to exist. What counts as intentionality for a naturalist proper is evidenced through behaviour, and it consists of a brain processing incoming information. The space of reasons, the finer points of language, art, morality, knowledge and so forth can be talked about as abstractions. They are useful in the processing that the brain must do; they result in digestible inputs. But the naturalist proper is ever-mindful that these are not things in themselves, but that they are always identical with and reducible to the states of the brain. The same holds of spontaneity. The naturalist counts human judgments to be determined (in a deterministic or indeterministic sense[6]) by the physical processes that cause them. Thus, spontaneity can be said either to not really exist, or at least to be denied status as sui generis, as is the case with the other ideas McDowell wants to preserve. Where McDowell wants to say that human beings are free to choose their beliefs, to take their experiences and spontaneously form judgments about them, the proper naturalist denies this. For the naturalist proper, sometimes brain states will have the disposition to respond to the stimulus of a red bench and form the belief that there is a red bench. Sometimes, because of other beliefs, brain states will not have such a disposition and will not form such a belief. Whether or not this happens is not an act of spontaneity, but a function of the states of the brain, including the stimulus received and the beliefs already held.

By positing an autonomous space of reasons, and a second nature with which humans can access it, the naturalized platonist gains little in the way of explanation and much in the way of recalcitrant philosophical questions. McDowell thinks that he gets out of the “threat of supernaturalism” (78) by saying that scientific advancements don’t clarify nature as a whole, but only the realm of law. This step does not work; it only redefines “nature” to include what the naturalist counts as supernatural. McDowell renames nature as the realm of law, says that the platonic heaven, the space of reasons, also exist, and says that there’s this new thing, now called nature, previously called existence, which encompasses all of them. The connection between the realms of laws and reasons is as sketchy as ever, and it is only through proper naturalism of intentionality and spontaneity that the confusion is finally dissolved.


[1] See: Heidegger, Martin. Being and Time. Trans. John MacQuarrie and Edward Robinson. New York: Harper & Row, 1962. p. 98; p. 69 in the original German.

[2] String theories and wave-particle duality in physics play a role here, but they are beside the point. Scientific skepticism about what substances are physically is important. Equally important is the fact that extra-physical phenomena haven’t turned up at all. That is, the naturalist account is the best lead we have.

[3] From Sellars.

[4] …because we are always our physical selves and are never apart from our brains.

[5] From Nagel.

[6] Indeterminism as is afforded by quantum mechanics offers a sort of natural spontaneity, but it is not immediately clear how, or even if, this would impact judgments. #

Epistemology, Logic

In his essay “Empiricism and the Philosophy of Mind” (1955-56), Wilfrid Sellars launches an attack against sense-datum theorists. I don’t want to defend sense-data because I think that’s a flawed concept, but I do want to point out a misstep that Sellars makes in this paper.

This objection has probably been made before, but for the sake of my notes I’m spelling it out as I read it.

In the paper, Sellars runs through a set of three propositions that he believes that sense-datum theorists must hold, but that Sellars believes is inconsistent.
Continue Reading #


Do you know that this is a barn?

A good old fun topic: luck in epistemology.

If you’re familiar with the study of knowledge, you may know that, traditionally, knowledge is defined as justified true belief.

However, not all philosophers agree with this assertion. Edumnd Gettier famously created what’s known as the “Gettier problem”, by presenting some examples (the Gettier counterexamples, as they are known) of instances of justified true belief that do not correspond with our intuitive notion of knowledge.  Since that time, more examples have surfaced that closely resemble what we would normally call knowledge, but challenge the traditional definition.  I’ll use one example that was not given by Gettier, which I think sums up the idea of luck in epistemology very well.

Carl Ginet of Cornell University provides this example of lucky knowledge.  He imagines that a person, Henry, is driving down a country road and sees a barn.  In his mind, he forms the belief that he sees a barn.  His belief is justified, because the object he sees appears to be a barn — it matches his understanding of what a barn is, how a barn looks, etc.  His belief is also true, because what he sees is, in fact, a barn.

However, things are more interesting than that.  For, in the area that Henry finds himself, the locals have an odd hobby.  They like to construct facades of buildings, which, from the road, appear identical to actual buildings.  In fact, the majority of the things that look like barns from the road are not actually barns, but wooden facades that only look like barns.

Now, here’s the problem.  Henry has a justified true belief that he sees a barn, which, in the traditional account, means that he knows that he sees a barn. But it’s only by sheer luck that Henry is actually correct in his belief.  If Henry had happened to be looking at any of the other barn-like objects in the area, he would have been wrong.  This begs the question: Does Henry really know that he is looking at a barn?

If you answer “yes” to that question, then consider the following.  Suppose that someone next to him is familiar with the area, and tells Henry that, “actually, the people in this area construct facades of buildings, and most of the things that look like barns around here are, in fact, not barns.”  If Henry is told this, but nobody confirms that he is actually looking at a real barn, does he still know that he is looking at a barn?  It would seem that his true belief is no longer justified — given what he now knows about the area, he doesn’t have a good enough reason for believing what he previously knew to be true.

Did Henry go from knowing something to not knowing it? If so, than to what degree is knowledge dependent on our state of mind?  If not, did he ever know it, and can we ever know something luckily, or are there other qualifications to knowledge other than it being justified and true?

Duncan Pritchard, a professor at the University of Edinburgh, Scotland, performs what is probably the first thorough examination of this concept in his book, Epistemic Luck.

I’ll leave it at that, for now, to bring up the idea of epistemic luck.  It’s something that I’ll be keeping in the back of my mind this year as the epistemology topics come up.  I’ll be beginning my second year tomorrow, which, fortunately, has a greater focus on philosophy than my first year.  I’ll probably come back to this idea in a later post, as epistemology is one of my favourite areas of philosophy.

PHOTO CREDIT: iowa_spirit_walker / CC BY 2.0 #