A Problem In Hume

 

A Problem in Hume

 

 

 

Early in the TreatiseHume sets out to establish what he calls a “general proposition”, namely: “That all our simple ideas in their first appearance are deriv’d from simple impressions, which are correspondent to them, and which they exactly represent” (Book I, Section I, p.52).[1]What kind of proposition is this? It is evidently a causal proposition, to the effect that ideas are caused by impressions, and not vice versa: the word “deriv’d” indicates causality. So Hume’s general proposition concerns a type of mental causation linking impressions and ideas; accordingly, it states a psychological causal law. It is not like a mathematical generalization that expresses mere “relations of ideas”, so it is not known a priori. As if to confirm this interpretation of his meaning, Hume goes on to say:  “The constant conjunction of our resembling perceptions [impressions and ideas], is a convincing proof, that the one are the causes of the other; and this priority of the impressions is an equal proof, that our impressions are the causes of our ideas, not our ideas of our impressions” (p. 53). Thus we observe the constant conjunction of impressions and ideas, as well as the temporal priority of impressions over ideas, and we infer that the two are causally connected, with impressions doing the causing. In Hume’s terminology, we believe his general proposition on the basis of “experience”—our experience of constant conjunction.

But this means that Hume’s own critique of causal belief applies to his guiding principle. In brief: our causal beliefs are not based on insight into the real powers of cause and effect but on mere constant conjunctions that could easily have been otherwise, and which interact with our instincts to produce non-rational beliefs of an inductive nature. It is like our knowledge of the actions of colliding billiard balls: the real powers are hidden and our experience of objects is consistent with anything following anything; we are merely brought by custom and instinct to expect a particular type of effect when we experience a constant conjunction (and not otherwise). Thus induction is not an affair of reason but of our animal nature (animals too form expectations based on nothing more than constant conjunction). Skepticism regarding our inductive inferences is therefore indicated: induction has no rational foundation. For example, prior to our experience of constant conjunction ideas might be the cause of impressions, or ideas might have no cause, or the impression of red might cause the idea of blue, or impressions might cause heart palpitations. We observe no “necessary connexion” between cause and effect and associate the two only by experience of regularity—which might break down at any moment. Impressions have caused ideas so far but we have no reason to suppose that they will continue to do so—any more than we have reason to expect billiard balls to impart motion as they have hitherto. Hume’s general proposition is an inductive generalization and hence falls under his strictures regarding our causal knowledge (so called); in particular, it is believed on instinct not reason.

Why is this a problem for Hume? Because his own philosophy is based on a principle that he himself is committed to regarding as irrational—mere custom, animal instinct, blind acceptance. He accepts a principle—a crucial principle–that he has no reasonto accept. It might be that the idea of necessary connexion, say, is an exception to the generalization Hume has arrived at on the basis of his experience of constant conjunction between impressions and ideas—the equivalent of a black swan. Nothing in our experience can logically rule out such an exception, so we cannot exclude the idea based on anything we have observed. The missing shade of blue might also simply be an instance in which the generalization breaks down. There is no necessityin the general proposition Hume seeks to establish, by his own lights–at any rate, no necessity we can know about. Hume’s philosophy is therefore self-refuting. His fundamental empiricist principle—all ideas are derived from impressions—is unjustifiable given his skepticism about induction. Maybe we can’t helpaccepting his principle, but that is just a matter of our animal tendencies not a reflection of any foundation in reason. It is just that when we encounter an idea our mind suggests the existence of a corresponding impression because that is what we have experienced so far—we expectto find an impression. But that is not a rational expectation, merely the operation of brute instinct. Hume’s entire philosophy thus rests on a principle that he himself regards as embodying an invalid inference.

It is remarkable that Hume uses the word “proof” as he does in the passage quoted above: he says there that the constant conjunction of impressions and ideas gives us “convincing proof” that there is a causal relation that can be relied on in new cases. Where else would Hume say that constant conjunction gives us “convincing proof” of a causal generalization? His entire position is that constant conjunction gives us no such “proof” but only inclines us by instinct to have certain psychological expectations. And it is noteworthy that in the Enquiry, the more mature work, he drops all such talk of constant conjunction, causality, and proof in relation to his basic empiricist principle, speaking merely of ideas as “derived” from impressions. But we are still entitled to ask what manner of relation this derivation is, and it is hard to see how it could be anything but causality given Hume’s general outlook. Did he come to see the basic incoherence of his philosophy and seek to paper over the problem? He certainly never directly confronts the question of whether his principle is an inductive causal generalization, and hence is subject to Humean scruples about such generalizations.

It is clear from the way he writes that Hume does not regard his principle as a fallible inference from constant conjunctions with no force beyond what experience has so far provided. He seems to suppose that it is something like a conceptual or necessary truth: there couldnot be a simple idea that arose spontaneously without the help of an antecedent sensory impression—as (to use his own example) a blind man necessarily cannot have ideas of color. The trouble is that nothing in his official philosophy allows him to assert such a thing: there are only “relations of ideas” and “matters of fact”, with causal knowledge based on nothing but “experience”. His principle has to be a causal generalization, according to his own standards, and yet to admit that is to undermine its power to do the work Hume requires of it. Why shouldn’t the ideas of space, time, number, body, self, and necessity all be exceptions to a generalization based on a past constant conjunction of impressions and ideas? Sometimes ideas are copies of impressions but sometimes they may not be—there is no a priori necessity about the link. That is precisely what a rationalist like Descartes or Leibniz will insist: there are many simple ideas that don’t stem from impressions; it is simply a bad induction to suppose otherwise.

According to Hume’s general theory of causation, we import the idea of necessary connexion from somewhere “extraneous and foreign”[2]to the causal relation itself, i.e. from the mind’s instinctual tendency to project constant conjunctions. This point should apply as much to his general proposition about ideas and impressions as to any other causal statement: but then his philosophy rests upon the same fallacy–he has attributed to his principle a necessity that arises from within his own mind. He should regard the principle as recording nothing more than a constant conjunction that he has so far observed, so that his philosophy might collapse at any time. Maybe tomorrow ideas will notbe caused by impressions but arise in the mind ab initio. Nowhere does Hume ever confront such a possibility, but it is what his general position commits him to.

 

Co

[1]David Hume, A Treatise of Human Nature(Penguin Books, 1969; originally published 1739).

[2]The phrase is from Section VII, [26], p. 56 of An Enquiry Concerning Human Understanding(Oxford University Press, 2007).

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Is Solipsism Logically Possible?

 

 

Is Solipsism Logically Possible?

 

 

It has been commonly assumed that solipsism is logically or metaphysically possible. I could exist without anything else existing. There are possible worlds in which I exist and nothing else does. I can imagine myself completely alone. Seductive as such thoughts may appear, I think they are mistaken; they arise from a confusion of metaphysical and epistemic possibility.

Suppose someone claims that this table in front of me could exist in splendid isolation, the sole occupant of an ontologically impoverished world—no chairs, planets, people, birds, etc. Well, thatseems true—those absences are logically possible. But what about the piece of wood the table is made of? This table is made of that piece of wood in every possible world in which it exists, so the table cannot exist without the piece of wood. But that piece of wood came from a particular tree—it could not have come from any other tree. So this table can only exist in a world that alsocontains the tree in question, since it was a part of that tree. The table and the tree are distinct existences, so the table cannot exist without something elseexisting—the tree that donated the part that composes it. The table is necessarily composed of that piece of wood and that piece of wood necessarily derives from a particular tree: there are necessities linking the table with another object, viz. the tree. Thus “solipsism” with respect to this table is not logically possible.

Now consider a person, say me. I could not exist without my parents existing, since no person could be thisindividual and not be born to my parents. This is the necessity of origin as applied to persons. In any world in which I exist my parents exist; more precisely, in any world in which I exist a particular sperm and egg exist (and they can exist only because of the human organisms that produced them). So my existence implies the existence of my parents. Therefore solipsism is not logically possible. But the existential ramifications go further: my parents cannot exist in a world in which theirparents don’t exist. And so on back down the ancestral line, till we get to the origin of life: no later organism can exist without the procreative organisms in its ancestral line. Every organism has an origin, and that origin is essential to its identity. But it goes even further, because the very first organism must have had its own inorganic origin, presumably in a clump of molecules, and that origin is essential to it—itcould not exist without thatclump existing. And that clump of molecules also had an origin, possibly in element-forming stars; so it couldn’t exist without the physical entities that gave rise to it. And those physical entities go back to the big bang, originating in some sort of super-hot plasma. So I (thisperson) could not exist unless the whole chain existed, up to and including certain components of the big bang. Colin McGinn could not exist without millions and millions of other things existing, granted the necessity of origin. I am linked by hard necessity to an enormous sequence of distinct particulars. I couldn’t be mewithout them.

Of course, there could be someone just likeme that exists in the absence of my specific generative sequence—though he too will necessarily carry his own generative sequence. Perhaps in some remote possible world this counterpart of mine arises not by procreation but by instantaneous generation—say, by lightning rearranging the molecules in a swamp. But even then that individual would not be able to exist without hisparticular origins—his collection of swampy molecules and that magical bolt of lightning. Solipsism will not be logically possible even for him. In any case, the question is irrelevant to whether Icould exist without my generative sequence: my counterparts are not identical to me. All we are claiming is that solipsism is logically impossible so far as Iam concerned—this specific human being. It is myexistence that logically (metaphysically) requires the existence of other things—lots of other things. I (Colin McGinn) could never exist in another possible world and peer out over it to find nothing but myself (at least throughout history–I might exist without any other organism existing at the same time as me, my parents both being dead). The same applies to any person with the kind of origin I have, i.e. all human beings.

Why do we feel resistance to these crushingly banal points? I think it is in part because we confuse a metaphysical question with an epistemological question; and we cannot answer the epistemological question by appealing to our answer to the metaphysical question. The epistemological question is whether I can now provethat solipsism is false: can I establish that I am not alone in the universe? In particular, can I establish that my parents really exist (or existed)? Maybe they are just figments of my imagination; maybe I was conceived by lightning and swamp. I cannot be certainthat I was not. I cannot even be certain that I have a body. I can establish that I think and exist, but I cannot get beyond that in the quest for certainty. So the existence of my parents is not an epistemicnecessity. If I could prove that I am a member of a particular biological species, then maybe I could prove that I must have arisen by sexual reproduction from other members of that species: but the skeptic is not going to let that by–she will demand that I demonstrate that I ama particular kind of organism arising by sexual reproduction. And I will not be able to meet that challenge, since there are conceivable alternatives to it (the hand of God, swamp and lightning, the dream hypothesis). Maybe I just imaginethat I am a biological entity with parents and an evolutionary history. So we cannot disprove solipsism in the epistemological sense: for all I know, there is nothing in the universe apart from me.

But this is perfectly compatible with the thesis that it is not in factlogically possible for me to exist without other entities existing along with me: for if I ama biological entity born by procreation, then my existence logically implies the existence of many other things. It is just that I cannot prove to the skeptic’s satisfaction (or my own) that that is what I am. I might come to the conclusion that I had no parents after all, but that will not make it the case that there are metaphysically possible worlds in which I had no parents—this is a matter of the facts about me, not my beliefs about the facts. Thus solipsism is an epistemic possibility but not a metaphysical possibility. It is just like the table being both necessarily made of wood (metaphysical) and also being possibly not made of wood (epistemic). Giventhat I arose from biological parents, I necessarily did; but it is an epistemic possibility that I did not so arise—I could be mistaken about this.

It would be nice to disprove solipsism, but it isn’t insignificant to show that it is not in fact logically possible, given the actual nature of persons. Persons are the kind of thing that implies the existence of other things (granted that we are right in our commonsense view of what a person is). In this they resemble many ordinary biological and physical entities, which also have non-contingent origins. We may feel ourselves to be removed from the world that surrounds us, as if we are self-standing individuals, ontologically autonomous—as if our essential nature could subsist alone in the world. But that is a mistake—we are more dependent on other things than we are prone to suppose. We are more enmeshed in what lies outside of us than we imagine. We suffer from illusions of transcendence and autonomy. We are not free-floating egos that owe no allegiance to anything else; we are essentially relational beings, our identity bound up in our history. We cannot be metaphysically detached from our origins, proximate and remote.

The same point applies to our mental states: they too cannot be separated from other things. Could this pain exist in complete isolation? That may seem like a logical possibility, but on reflection it is not: first, this pain’s identity depends on its bearer—it could not be thispain unless it had thatbearer; and second, the identity of the bearer depends on the kind of history it has. So this pain could not exist without the generative sequence that gave rise to its bearer, a particular living organism; and that depends upon billions of years of history, going back to the big bang (and before). There is no possible world in which this painexists and certain remote physical occurrences don’t exist. There are necessary links connecting present mental states with remote physical occurrences—from the joining of a particular sperm and egg, to the origin of mammals, to the production of chemical elements. My pains can’t exist in a world without me (you can’t have mypains), but I can’t exist in a world without my parents, and my parents can’t exist in a world without their remote primate ancestors, and these ancestors too had their own necessary origins. The pains that now occur on planet Earth (thosepains) could not exist in a possible world without an elaborate biological and physical history that coincides with their actual history.

It is an interesting fact that we recognize these necessities. On the one hand, we have quite strongly Cartesian intuitions about the person and the mind, which is why dualism and solipsism appeal to us—these seemlike logical possibilities. But on the other hand, we are willing to accept that the person and mind are tied to other entities with bonds of necessity—as with the necessity of personal origin. We recognize that the identity of a person cannot be radically detached from all extrinsic and bodily things—parents, sperms, and eggs. These are anti-Cartesian intuitions insofar as they dispute the self-subsistence of the self.[1]We are thus both Cartesian and anti-Cartesian in our modal instincts about persons. It is as if we know quite well that the self cannot be a self-subsistent non-material substance without logical ties to anything beyond itself, even though in certain moods we fall prey to such thoughts. We know that our essence implies the existence of other things—as demonstrated by the necessity of origin—and therefore solipsism is not in fact logically possible. We are modally ambivalent about self and mind, but not confused.

 

Colin McGinn

[1]Kripke mentions the anti-Cartesian consequences of the necessity of origin at the very end of Naming and Necessity(footnote 77, p. 155). What is surprising is that neither he nor anyone else seems to have noticed the consequences for solipsism (including myself, and I published an article on the necessity of origin in 1976). But it is really just a fairly obvious deduction from the necessity of origin (originally proposed by Sprigge in 1962, as Kripke notes).

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An Obvious Theory of Truth

Truisms are welcome in the theory of truth. Here is one: the sentence “London is rainy” if true if and only if the entity referred to by “London” has the property expressed by “rainy”. Generalizing, a sentence (or proposition) is true just in case the reference of the subject expression instantiates the property expressed by the predicate expression. This formula combines two concepts: a semantic concept of reference (denotation, expression) and the concept of instantiation understood as a non-semantic relation between objects and properties. Truth results when the entities denoted (objects and properties) stand in the instantiation relation. So we can say that truth consists of a combination of a semantic relation and a non-semantic relation: it is the “logical product” of these two relations. The analysis of truth is given by a “vertical” relation to the world and a “horizontal” relation between worldly entities. Thus “true” expresses a complex property comprising representation and instantiation—that is what the concept amounts to. Both are necessary for truth and together they are sufficient. Moreover, the formula is the most banal of truisms: of course a sentence is true if the things it talks about have the properties the sentence attributes to them. The sentence “snow is white” is true just if the stuff it refers to (snow) has the property the sentence ascribes to it (being white). How could this fail to be correct?[1]

Some minor wrinkles can be quickly ironed out. Is the theory (let’s call it that) ontologically committed to properties in some objectionable platonic sense? I stated it that way, but this is not integral to the theory (though metaphysically unobjectionable, in my view): we could state it in terms of concepts or even just predicates—as in the notion of an object falling into the extension of a predicate. Nor is the theory committed to sentences as truth-bearers: we can run it on propositions, statements, beliefs, what have you, so long as we have a relation like denotation to work with.  It might be thought that the theory is restricted to subject-predicate sentences and won’t extend to quantified sentences, but this limitation is easily remedied by adding that the objects referred to or quantified over should instantiate whatever is predicated of them. Whatever objects are semantically relevant are the ones that need to do the instantiating if the sentence is to be true. What about moral truths? Well, if there are such truths the theory commits us to the idea that moral sentences can be true only if there are moral properties (or concepts or predicates) for objects to instantiate—but this will presumably be so if there are moral truths to start with. What we don’t get are nonsensical truths, because there will be no objects and properties to stand in the instantiation relation (e.g. borogroves and mimsiness). We just have the commonsense thought that whether a sentence is true depends on what objects have which properties. If you say that an object has a property and it does, your statement is true; but if you say that an object has a property and it doesn’t, your statement is false. Clear?

What is surprising is that this theory, if we can dignify it with that word, has not been mooted (at least to my knowledge), since it seems blindingly obvious.[2] Some theories in its vicinity have been mooted, but not this theory exactly. It certainly carries the whiff of the correspondence theory, but it invokes no relation between whole propositions and facts, speaking instead of objects and properties and associated sentence-parts. The world comes into the picture, but not by way of a correspondence relation between facts and propositions. Nor is it a redundancy theory, since it defines truth as a complex property constituted by substantive relations; still less is the theory deflationary. It is also not the same as Tarski’s theory: the schema employed does not repeat on the right the sentence mentioned on the left (so it doesn’t satisfy Convention T) but rather embeds semantic vocabulary and the notion of instantiation. It is possible to universally quantify an instance of the schema and produce a well-formed result, whereas that is not possible for Tarski’s schema. We can say, “For all propositions x, x is true if and only if the objects referred to in x instantiate the properties expressed in x”, but we can’t say, “For all propositions x, x is true if and only if x”, because that is not well-formed (“x” being an individual variable not a sentence letter). Also, the definition proposed by the obvious theory is explicit, not inductive, and applies to any sentence in any language (we are not defining “true-in-L”).[3] The theory is closer to a formulation championed by P.F. Strawson: a statement is true if and only if “things are as they are thereby stated to be”. The spirit looks the same, but what are these “things”, and where is the reference to properties and their instantiation? It sounds a lot like saying, “if and only if reality is as stated”: but that is not the same as the formulation in terms of objects and properties. Perhaps the obvious theory could be read as a more explicit version of this type of theory; and indeed it looks very much like what people were driving at all along. For surely we want to say that the truth of a statement turns on the instantiation of properties by objects combined with suitable semantic relations to those objects and properties. To say something true you have to refer to an object and then assign a property to it that it actually has—obviously.

Consider the locution “true of”: what is its analysis? Obviously this: a predicate is true of an object if and only if the object has the property expressed by the predicate. This is the core of the obvious theory: truth itself is defined by reference to “true of” (as Tarski defines truth in terms of “satisfies”). We might say that “true of” is the basic notion in the theory of truth. We reach truth of propositions by plugging in a singular term: from “F is true of x” we derive “F is true of a” where “a” is a closed singular term (say a proper name). Thus the sentence “Fa” is true just if the predicate “F” is true of the object referred to by “a”. The other theories of truth remain neutral on the analysis of “true of”, which is a limitation in any attempt to define the concept of truth generally; but the obvious theory puts it at the center. To say something true you have to apply a predicate to what it is true of. And that is a matter of picking a predicate that expresses a property that applies to the object.

The OED defines “true” as “in accordance with fact or reality”. Fair enough, but what is “in accordance with” and what is “fact or reality”? The correspondence theory suggests some sort of isomorphism between propositions and complexes called facts. The obvious theory says that truth is a matter of identified objects instantiating assigned properties; so accordance is simply objects having the properties they are said to have. A statement is in accordance with reality just on the condition that it assigns properties to objects as they are actually distributed, i.e. as they are. Fact and reality are just objects having properties. This is a substantive definition of truth meeting standard conditions of adequacy: it defines truth in terms of notions severally necessary and jointly sufficient; it is non-circular; and it permits a universally quantified formula that captures our intuitions about truth. To repeat it in a slightly different language, a proposition is true if and only if its subject matter (objects and properties) exemplifies suitable instantiation relations. Truth is a matter of objects instantiating properties in the way alleged by a proposition. To understand the concept of truth, then, we need to grasp this complex of concepts: reference, object and property, instantiation. It is not simply a device of semantic ascent or essentially redundant or logically simple or merely a means of abbreviation. It is a thick analytically deep concept with a definite nature. Yet its nature is entirely (indeed painfully) obvious—not in the least bit surprising. The truth about truth is a true truism.[4]

 

[1] The same form of analysis can be applied to the concept of justification, which I take to be confirmation of the theory: a proposition is justified if and only if there are good reasons to believe that the objects referred to instantiate the property expressed. Likewise, we can say that it is a fact that p if and only if a certain object instantiates a given property, e.g. London instantiates being rainy (notice that no semantic relation is involved here).

[2] Why this should be is not clear to me: perhaps it is thought too obvious, or perhaps less obvious theories are confounded with it (correspondence theories).

[3] Devotees of Tarski’s theory will want to know how to provide recursion clauses for logical connectives. This is easily done: for example, “p and q” is true if and only if the objects and properties referred to in “p” stand in the instantiation relation and the objects and properties referred to in “q” stand in the instantiation relation; and similarly for “or” and “not”.

[4] Why is the truth about truth a truism while the truth about (say) knowledge is not? Because there is nothing more to the truth of propositions than objects instantiating properties combined with the fact that propositions stand for things. There is nothing hidden here, nothing to be discovered. Other theories purport to say something interesting, but the obvious theory is content with mere accuracy.

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Quantifier Concepts

Would it be quixotic to suppose that quantifiers hold the secret to human success?[1] Could the student of quantification theory be studying the ultimate differentia that separates humans from the rest of nature? That would be a delightful result for the logically minded; and I think there is actually a good deal to be said for it. For it is plausible to suppose that what other animals lack, cognitively speaking, and we splendidly possess, is the ability to engage in quantifier-driven reasoning. We grasp what Quine called the “apparatus of quantification” but they do not—though they no doubt grasp much else. That apparatus, to put it briefly, involves the existential and universal quantifiers, variable binding, embedding, scope, domain, and a distinctive syntactic form—not to mention the non-standard quantifiers “most”, “a few”, “many”, and others. Suppose all this represented in the human language of thought.  Then we can surmise that other animals, though cognitively gifted in many ways, lack an internalization of the apparatus of quantification—though they may well entertain singular and general concepts, truth functions, psychological concepts, etc. At any rate, there are possible beings that have mastery of a conceptual apparatus just like ours except that quantification is not included. The question is what capacities they would thereby lack that we possess, and which confer signal advantages on us. What do quantifiers do for you? What mental achievements do they make possible?

Quantifiers are obviously deeply embedded in our thinking, so it is not easy to tease out their contribution, but certain areas of human thought clearly depend on them.  First, science: where would science be without the universal quantifier? A law is precisely a generalization about all things of a certain kind (we can include ceteris paribus laws). If you don’t grasp the concept all, you don’t know what a law is. Similarly, you have to grasp that if some things lack a certain property then it is not a law that all things have that property (I omit some obvious qualifications). Quantificational reasoning is essential to scientific thought (animals don’t seem strong with science): science consists of universally quantified propositions. Second, mathematics: this too is shot through with quantificational structure (it was mathematics that caused Frege to invent modern quantification theory). The most basic axiom of arithmetic is universally quantified: for every number, there exists a successor number. Peano’s axioms are quantificational in form. The embedding of quantifiers is rife in mathematics. Geometry is much the same: we have theorems about all triangles, circles, etc. Moreover, according to some views, arithmetic reduces to quantification theory (plus set theory, which is itself formulated by means of quantifiers). Standard first-order predicate logic is clearly quantificational, but so is second-order logic (which greatly increases expressive power). Propositional logic discerns no quantifiers in its formulas, but it is tacitly quantificational itself, since sentence letters are interpreted generally: for any p and q… We understand it to express universal propositions. That is what logical necessity consists in. Modal logic involves quantification over possible worlds (necessity and universality are close cousins). Inductive logic involves moving from singular premises to general conclusions and would be impossible in the absence of the concept everything. Falsification depends on there being some counter-instance to a generalization. All this would be impossible for beings without a mental representation of the apparatus of quantification. When we reason we move from the particular to the general and the general to the particular, and this requires grasping how all and some work; not to grasp these principles would be a severe cognitive deficit (“quantifier derangement syndrome”). If Russell is right, definite descriptions are not possible without quantification (do animals grasp definite descriptions?); they are built from the quantifiers “all” and “some”. Many pronouns function as bound variables. Lastly, cosmology requires the use of the ultimate universal quantifier: for it concerns the nature of everything (ditto metaphysics). Here we ascend from specific domains to the entire domain of the universe. It is remarkable that we have such an all-encompassing concept—we can think about everything there is. Can animals ever think about the whole enchilada? I doubt it: they think specific and particular, local and limited. Maybe their thought is largely demonstrative, or maybe it employs a medium alien to human thought. In any case, our cognitive resources include the extensive and intricate apparatus of quantification, which greatly expands our powers of mental representation and hence our understanding of the world.[2] In turn, this enhanced understanding feeds into our actions and mode of life. We are quantifying creatures (other creatures could be rational beings but not quantifying beings).

Let me note two further features of quantifier concepts that set them apart. We know from the work of logicians that they are not semantically singular terms but a sui generis type of expression; they occupy their own category in mental grammar. It is sometimes said that they are second-order concepts, i.e., concepts of concepts, and this sets them apart from their first-order brethren. To grasp them, you have to be able to ascend a level and predicate them of a concept: this requires a cognitive leap, a new mode of mental representation. Creatures with only first-order concepts are not guaranteed to be capable of achieving this new level, however hard they think. Presumably, it occurred at some point in human cognitive evolution, perhaps triggered by a specific mutation affecting brain circuitry, and not shared by other species. Perhaps we have a gene for quantification! Some piece of brain rewiring caused us to be able to grasp second-order concepts like all and some, where there was no such grasp before. Then we were off to the races, with science, logic, mathematics, and cosmology on the horizon. A new cognitive trick catapulted us to the next intellectual level. Imagine if you lacked these concepts and were stuck at the level of the specific and particular: then a super-scientist rewires your brain to give you a grasp of quantification. Wouldn’t that be a stunning intellectual breakthrough, opening up vast avenues of new understanding and reasoning power? The child picks it all up automatically along with the other remarkable resources of human language, but that doesn’t mean it isn’t a signal achievement—imagine losing it one day! Quantification is a classy mental act, belonging only to the intellectual elite, by no means proletarian.

Secondly, quantifier concepts are unique as to content: no other concept is such a bad candidate for empiricist treatment.[3] How could the concepts all and some be derived by a copying operation from sensory stimuli? They are not concepts of a sensory quality, or of any mental operation. I am tempted to call them abstract, but that is just a vague way to register their distinctness from other types of concept. I would guess they are innate—for how could they be picked up from observation of the environment? They enter our thought at an early age and shape it pervasively, but their origins are obscure. They are part of the universal human lexicon, but they name nothing and describe nothing. Form the thought “Everything changes” and ask yourself what is going on in your mind: you will find no discernible constituent corresponding to the quantifier—no image or feeling or disposition. There is nothing…concrete here. Yet you mentally took in all of reality! How is that possible? What do you have that your cat doesn’t have? I mean: how is the concept of universality mentally represented? Can we have a description theory of it? How about a causal theory? Neither seems remotely feasible. We are used to the words (and their corresponding logical symbols) but what is the content exactly? Where is the cognitive science of quantification? What we have here is a complex and intricate biological adaptation of enormous utility but quite opaque in its mode of operation. It took logicians thousands of years to identify it and describe its logical character, but its psychology is not even in its infancy (or its neuroscience). The point I am urging is that it has some claim to distinguish us from other thinking beings on our planet. Let us grant that bees, whales, and dolphins have communication systems, along with associated cognitive structures—but it is a further claim to maintain that they understand quantification as humans do.[4] All humans do understand it (short of pathology), but there is no evidence that other animals can engage in quantificational reasoning (just consider the difficulties of embedded quantifiers).

It is not implausible to suppose that humans go through an ontogenesis in which “all” begins locally and then gradually widens to take in more and more of reality. Thus the child initially applies “all” to all the marbles on the table or all the apples he can see, later expanding the domain to include all the marbles or apples on earth. But that isn’t enough to yield the adult concept: the child must include all past and future marbles and apples, as well as any found elsewhere in space. Then there are all the possible marbles and apples. Finally, we reach everything there is. The original concept (innately present, we can suppose) already contained this potential, but it undergoes a process of maturation that ends with the cosmic all. This would be in conformity with standard views of linguistic and conceptual development. But the process has a special interest because the concept is so all-encompassing in its nature: its enormous reach signifies a kind of supremacy among concepts—it is the king of all concepts, as it were. Every other concept is subordinate to it, literally. Doubtless, it is a concept that has fueled the acts of many a despot or madman, or metaphysician or cosmologist (a “theory of everything”). God is described as all-powerful, all-knowing, and all-virtuous: the recipient of every estimable universal quantification. So much majesty revolves around this concept—its place in human thought is unrivaled.[5] Once the child has fully absorbed this concept (or it has fully matured within her) she becomes a being of a different cognitive order from the run of terrestrial animals, including her former self. Morality is stamped with it too: duty is what everyone ought always to do in any circumstances (remember Kant’s categorical imperative, in which universalization is paramount). We would not be the cognitive (and emotional) beings we are without this capacious and ubiquitous concept. When Aristotle enunciated his famous syllogism beginning “All men are mortal” he was drawing attention to the mighty power of that little word “all”: once you know that all F’s are G you know something of high significance from which many interesting things follow. In it may reside our capacity for the type of thought that defines human nature.[6]

 

Colin McGinn

[1] I am slightly misusing the word “quixotic” here, but the alliteration was irresistible.

[2] George Eliot reminds us of a downside to this mental advantage over other animals: “But this power of generalizing which gives men so much the superiority in mistake over the dumb animals…” (Middlemarch, 592) Our ability to generalize lays us open to errors of thought unknown to animals lacking this capacity; and it must be said that quantifiers can cause us no end of trouble—especially the standing temptation to abuse “all” in the presence of “some” (quantificational malfeasance).

[3] I know this is saying a lot given empiricism’s poor track record, but a bit of overstatement may be forgiven in the light of the fact that one never hears much about quantifier concepts from empiricists (I don’t recall Hume discussing them at all). They are expected to take care of themselves.

[4] Given other differences between human and animal thought, it might be more apt to compare humans to other hominids now extinct. What if Neanderthals matched humans cognitively except where quantification is concerned? That could be the reason for our relative success.

[5] What is the connection between death and the universal quantifier? Simply this: when you die it is all over. Everything about you has gone. You are now nothing. The quantifiers say it all. We understand what death is because we can use quantifiers this way.

[6] People often discuss this question as if it is all-or-nothing matter—either we share thought with animals or we don’t. But a more nuanced discussion can focus on whether there are any areas of human thought inaccessible to other thinking beings. Thought may not be homogeneous in its nature and origins (similarly for language). Quantification may have been added quite late in the game.

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The Mind-World Nexus

 

The Mind-World Nexus

 

 

According to a dominant tradition, appearances are not “in” objects: that is, how an object appears is not (completely) determined by its objective properties but depends on the mode of sensibility employed to perceive it.  The classic example is color: objects are not colored independently of how they seem but in virtue of the color sensations they elicit in perceivers. Thus we can conceive of variations of color without an intrinsic variation in the object but merely in virtue of being differently perceived (Martians may see as green what we see as red). Color is then relative to a type of perceiver—and not just perceived color but actual color. An object isred if and only if it seemsred to a suitable group of perceivers. We could put this point by saying that color is extrinsic to objects; it depends on what kind of perceiver exists in the object’s environment. If the environment contains one kind of perceiver (humans), then it is red; but if it contains contains another type of perceiver (Martians), then it is green. The color depends on context—on how the object is hooked up to experience. It would be wrong to think that color is internalto objects, as if objects could have determinate colors no matter how they are perceived. And much the same can be said of other sensible qualities associated with hearing, touch, smell and taste. Perhaps it is true that not all apparent qualities are thus subjective, such as shape and size, but many are. As is often said, such qualities are projected by the mind, generated from within, and spread on objects. They depend on the “psychological environment” of the object (no perceivers, no qualities).

I have put the point by using terms drawn from another debate, namely the debate between internalism and externalism about the mind. It is claimed that what kind of mental state a person has is dependent on his or her environment and is not a result of purely internal factors.[1]We can vary a person’s environment while keeping her internal states the same (Twin Earth cases), and when we do so we find that mental states track the environment. So mental states are extrinsically fixed (in part anyway) and environmentally sensitive. They are not “in” the subject—not locally supervenient, not a matter of internal facts. They depend on the physical context, on how the person is hooked up to his environment. So there is an abstract analogy between certain views of color and certain views of mental states: both are regarded as relational and context-dependent. In the slogan, mental states are not “in the head”, but neither are sensible qualities “in the object”. The mental world is not independent of the physical world, and the physical world is not independent of the mental world. The subjective embeds the objective, and the objective embeds the subjective. Thus mind and world are mixed together, each incorporating the other, each flowing into the other. It is not that the whole being of the mind is sealed off from the environment, but neither is the whole being of the external world sealed off from the mind. The world contains projected properties, and the mind contains introjected properties. The mind shapes the world (in part), and the world shapes the mind (also in part). So there is no fundamental dualism here: the world is partly formed by the mind, while the mind is partly formed by the world. When you are aware of external objects you are aware of your own mental contribution to their appearance, but equally when you are aware of your mental states you are aware of the world’s contribution to them. The mind absorbs and projects; the world also “absorbs” and “projects” (it “absorbs” color and “projects” mental content). Mind and world work together to produce a reality of colored objects and content-bearing mental states (though I don’t suppose there is any teleology coming from the world). In other terminology, the mind externalizescolor and internalizescontent—as we might say (metaphorically) that the world “internalizes” color and “externalizes” content. Mind and world are mirror images of each other, abstractly considered.

In fact, we shouldn’t really be speaking any longer of mind and world, as if there is an exclusive dichotomy, since each is woven into the other: there are traces of mind in the perceived world and there are traces of the world in the formations of the mind. What we have is a mind-world nexus: a joining, a merging, an overlapping. What we call “the world” is not purely objective in nature, and what we call “the mind” is not purely subjective in nature. The mind is (partly) constituted by the world, while the world is (partly) constituted by the mind: properties drawn from one side of this divide are found located on the other side. The world I perceive is partly internal to me (i.e. projected), and the mind I introspect is partly external to me (not “in my head”). From the point of view of objects (not that they have one), the colors (etc.) they wear are donated from the outside, while they provide their own service by constituting the mental content of subjects. Fancifully, we might view this arrangement as a quid pro quo: give me your colors and I will give you content in return. More soberly, the mind has two capacities: the capacity to absorb (internalize) and the capacity to project (externalize). It employs external properties to form its conceptual landscape, and it draws on its own resources to confer perceptible properties on things (it is useful to see objects as colored, etc.).

This is not to say that there is no mind-independent external world, or that there is no world-independent mental reality. On the contrary, I would strongly deny both assertions.[2]It is only to say that the livedworld is infused with both—both the world of external objects and the world of inner perception and thought. This is quite consistent with allowing that there is another level of description under which objects have purely internal properties (call it physics) and a level of description under which minds also have purely internal properties (call it narrow psychology). We don’t in physics describe objects in terms of mind-dependent qualities, and we don’t in narrow psychology advert to environmentally fixed psychological kinds. Color doesn’t affect the motion of bodies and they can exist without it; similarly, the operations of mind can be characterized without reliance on wide content and minds can exist without such content. For the purposes of science, we could accept that the two worlds don’t overlap; and it would certainly be quite wrong to conclude that either idealism or materialism is true given the considerations advanced so far (not everything about the world is contributed by the mind and not everything about the mind is contributed by the world). Rather, the phenomenalworld—both mental and external—the world we directly experience—thatworld is a mixture of mental and physical. The world I seeis partly made up of projected properties, and the mind with which I am directly acquaintedis up to its neck in externalities (e.g. my concept water). There are two levels of description here: one is inherently dualistic and the other is not. The one that is not concerns the world that we commonly occupy—the world that we sense, feel, talk about, and take for granted (which includes the mind). The other world is largely theoretical, which is not to say any less real. Think manifest image and scientific image.

I want to point out how remarkable the aforementioned capacities of mind actually are. When the mind internalizes an external property it converts that property from being a feature of external objects to being a vehicle of thought—and these are completely different roles. The property becomes bound up with a concept, and a concept has all sorts of distinctive properties–notably being a constituent of thoughts. This is a brand new career for the property and not one for which it had any prior training. Once it is a constituent of a proposition, it is required to participate in logical reasoning as well as mental representation of states of affairs. What has water (the H2O stuff) got to do with that, or being square or being arthritic? How does the mind perform this conversion operation—repurposing a property to start a new life as a concept? Externalists never answer this question—they just point to examples that (purport to) establish the doctrine. But it is really very puzzling: for how can a feature of the environment enter the mind in such a way as to shape its operations? What is this internalizationthat we speak of? How, for example, is the property of being square made to function as a constituent of perceptual experience and of thought? Not by making the mind square! It seems to undergo a metamorphosis, but the mechanism of this metamorphosis is obscure at best and impossible at worst. It might even make one to give up on externalism completely. Likewise, we speak blithely of projection, but how is thissupposed to work? It is not that the mind literally throws color at objects! Nor does it secrete color onto objects. No, the operation is purely mental—an operation of spreadingin Hume’s metaphor. This is both unhelpful and positively misleading. How does the mind externalize color, when it is not colored itself? How does it generate the qualities projected? How does the projected quality always manage to hit its target, painting the leaves green and the roses red with such precision? Somehow the brain produces an impression of a single object that has both color and shape, exactly coordinated, but it is not supposed that shape is projected; so how does it manage to project one quality and introject the other? Projecting color seems like a magic power—quite unlike what a film projector does (here there is actual transmission of light waves). All we have are vague metaphors but no theoretical understanding. This doesn’t mean that the mind doesn’t perform the action in question; it only means that we don’t understand how. In other words, the projective and introjective powers of mind are a mystery. Yet they are fundamental to our entire view of things.

Look at how perception must operate second by second. At a given moment a state of affairs presents itself to the senses—say, a red bird 10 feet in front of your eyes. Your visual sense must internalize this scene, its various properties and arrangements. The scene must so imprint itself that a suitable percept is formed that can then function as input to behavior: this is a highly complex conversion process whose workings are still poorly understood. But at the same time the brain must carry out a projection operation that bestows color on the seen objects, which is rapidly updated over time. It must take in but it must also give out. These operations have to be coordinated and unified. The stimulus for color projection just consists of impinging light rays in which no color is to be found; on reception of these rays the brain must issue an instruction to retrieve a certain color impression, which must then be combined with various shape impressions. The input is not colored but the output is. How the brain does this is a mystery. We know that the cones of the retina must be involved, but how the nervous system contrives to generate and project color is unknown except in gross outline. The result is that the perceiver sees a colored object, where the existence of the color depends on the existence of perceivers to project it. So there is a continuous interplay between internalizing and externalizing operations, tightly intertwined. It is not that perception is all internalization, as very naive naïve realism might suggest; but nor is it all projection, as idealism might maintain. The world is contributing to the mind and the mind is contributing to the world. In this two-way nexus we find the world as it is lived. We internalize the world (hence psychological externalism) and we externalize the mind (hence color subjectivism). Thus mind and world become intermingled.[3]

 

Colin M

[1]I won’t defend externalism here or even fuss over formulation; neither will I defend the subjectivist view of color. I am more concerned with their implications when conjoined. I defend externalism in Mental Content(1989) and subjectivism in The Subjective View(1983).

[2]I would count myself a staunch externalist andinternalist about the mind, and a staunch subjectivist andobjectivist about objects of perception. The key is to make distinctions between types of property or fact.

[3]Much the same can be said of language and meaning: semantic externalism brings the world into meaning and hence involves internalization, but the structure of language also shapes our view of reality, since our concepts are bound up with the structures of language (verbs and nouns, objects and properties). We need not accept the extreme view that our entire conception of reality is fixed by our language, which can vary from speaker to speaker, in order to recognize that language can function in a projective manner, imposing its internal architecture on our view of things. Language takes in but it also reaches out—it spreads itself onto perceived reality. Thus grammar can function like color perception. Then too, there is Freudian projection, in which traits of oneself are projected onto others, while the mind also introjects authority figures like parents. It seems that the mind is fond of the introjection-projection dialectic.

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Al Franken

I just read the recent article in the New Yorker about Al Franken by Jane Mayer (July 29, 2019). It is a model of responsible journalism and lays the facts out admirably. He should clearly not have been forced to resign. It reminded me of when I met him in 2013 at George Soros’s wedding (though I had met him briefly a few years before at my gym in New York just after George W. Bush “won” the presidency for the second time). I told him my favorite Soros joke: “What is the difference between a Hungarian and a Romanian? They will both sell you their mother, but the Hungarian will deliver”. Franken said he thought it was a good joke. Now he has had his life destroyed.

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