Friday, February 7, 2014

Frege in Context

In anybody’s short list of significant philosophers and mathematicians of the nineteenth and twentieth centuries, Gottlob Frege will appear near the top. His direct and indirect influence extends to many philosophers and groups of philosophers, including those who were influenced by him in the sense of reacting against him.

Although Frege’s work may be characterized as late modern or early contemporary, he nonetheless has a historical context. His seminal work symbolic logic and the foundations of mathematics might mislead us into thinking that he does not have a connection to great thinkers of earlier centuries. We will see, however, that to understand Frege in his historical context, we must view him in terms of John Locke and John Stuart Mill.

In his Essay Concerning Human Understanding, Locke address, among many other topics, language and reference. Locke asserts that the only possible referent of a word is an idea in the mind of the speaker (or writer). But, he writes, men mistakenly assume that their words can also refer to two other things: the ideas in the minds of others and the (physical) objects themselves. Leaving aside the latter comment about objects, the former comment about ideas in the minds of other leads us to considerations about reference.

The radical skeptic can issue all manner of objections to talk about ideas in the minds of others, let alone words referring to such ideas. But even the less-than-radical skeptic, one who is sympathetic to such a scheme of reference, will have concerns: Locke is such a one, and he raises such concerns. He imagines that it’s acceptable to posit that the speaker’s words may refer to ideas in the minds of others. But even if this is allowed, further problems remain.

If the speaker’s words can simultaneously refer to ideas in the speaker’s mind and idea in the listener’s mind, how can we know that any one word will refer to the same idea in the speaker’s mind and the listener’s mind? If the speaker says the word ‘x’ and it refers to the idea x in the speaker’s mind, how do we know that it also refers to the idea x in the listener's mind, and not, e.g., to the idea y?

This question gives rise to Locke’s famous inverted spectrum example, and also to later examples like those given by Quine in his book Word and Object. These, and other types of qualia inversion problems, isolate the question of whether a word can refer reliably to an idea in more than one mind. Locke writes:

Words are often secretly referred first to the ideas supposed to be in other men’s minds. But though words, as they are used by men, can properly and immediately signify nothing but the ideas that are in the mind of the speaker; yet they in their thoughts give them a secret reference to two other things.

Although acknowledging the problem of inverted qualia - indeed, originating the problem - Locke also seems to be content to rely on experience, to the extent that for the practical purpose of daily life, language suffices. Whether or not the qualia be actually inverted - Locke points out that we could never know this - language would work as long as the inversion were consistent. He continues:

First, they suppose their words to be marks of the ideas in the minds also of other men, with whom they communicate: for else they should talk in vain, and could not be understood, if the sounds they applied to one idea were such as by the hearer were applied to another, which is to speak two languages. But in this men stand not usually to examine, whether the idea they, and those they discourse with have in their minds be the same: but think it enough that they use the word, as they imagine, in the common acceptation of that language; in which they suppose that the idea they make it a sign of is precisely the same to which the understanding men of that country apply that name.

Finally, Locke returns to his initial assertion, that words refer properly only to the ideas in the mind of the speaker. The fact that we do, in practical daily life, act as if words also referred to ideas in the minds of listeners, or to physical objects themselves, is something other than reference properly construed. Locke therefore distinguishes between reference and what he calls the ‘common acceptation’ of an utterance (or of a writing). Ian Hacking writes:

Does Locke support this doctrine of ‘secrete reference’? I think the very phrase is loaded with Locke’s characteristic irony. ‘Give me leave here to say’, he continues in case anyone has failed to take the point, ‘it is a perverting the use of words, and brings unavoidable obscurity and confusion into their signification, whenever we make them stand for anything but those ideas we have in our own minds.’ Signifying, remember, is a relation of precedence-or-consequence. So what Locke says seems correct. Note that another term is used in this passage, ‘the common acceptation’ of a word in a language. This is something quite different from signifying. Let us take, for example, the role of a name in some speech. Had the real Mark Antony said, ‘I have come to bury Caesar, not to praise him’, there would have been the idea of Caesar present in Mark Antony’s mind. That is what the name ‘Caesar’ signifies, for Antony. The third plebeian, despite the inane responses Shakespeare puts in his mouth, doubtless also has some idea (possibly not Antony’s) of Caesar. That is what the name signifies for him. In contrast, there is the actual person referred to, recently deceased. Finally there is, perhaps, something else in the public domain: everyone realizes that Rome’s tyrant is under discussion. This shared cognition we might, borrowing Locke’s phrase, call the common acceptation of the name ‘Caesar’. Common acceptation enables Antony to address the multitude. It is whatever is ‘public’ about the established use of a word.

With this Lockean framework, the work of Gottlob Frege is seen in context. One of Frege’s many accomplishments was to express more specifically and more technically that at which Locke had only hinted, or expressed with less exactitude. Ian Hacking continues:

The distinctions required were not made efficiently until the late nineteenth century, when Gottlob Frege had to legislate a distinction into the German language in order to avoid confusion. He took the word Sinn - which has been translated ‘meaning’ but in English is nowadays called ‘sense’ - as common acceptation. By way of contrast he used the word Bedeutung - equally translated ‘meaning’ but now fixed with the English word ‘reference’.

In of the famous passages which earned Frege his place in the history of philosophy, he introduces his distinction between sense and reference - the distinction between Sinn and Bedeutung.

The regular connexion between a sign, its sense, and its reference is of such a kind that to the sign there corresponds a definite sense and to that in turn a definite reference, while to a given reference (an object) there does not belong only a single sign. The same sense has different expressions in different languages or even in the same language. To be sure, exceptions to this regular behaviour occur. To every expression belonging to a complete totality of signs, there should certainly correspond a definite sense; but natural languages often do not satisfy this condition, and one must be content if the same word has the same sense in the same context. It may perhaps be granted that every grammatically well-formed expression representing a proper name always has a sense. But this is not to say that to the sense there also corresponds a reference. The words ‘the celestial body most distant from the Earth’ have a sense, but it is very doubtful if they also have a reference. The expression ‘the least rapidly convergent series’ has a sense; but it is known to have no reference, since for every given convergent series, another convergent, but less rapidly convergent, series can be found. In grasping a sense, one is not certainly assured of a reference.

Here arises an interpretive question in the history of philosophy. Shall we spin the credit in Locke’s favor or in Frege’s favor? If we tilt it toward Locke, we might say that Locke conceptualized and expressed an important distinction about language, and that Frege merely tidied up the vocabulary used to express it. If we tilt it toward Frege, we might say that Locke was only vaguely aware this distinction, and that Frege uncovered and discovered and clearly articulated it. Ian Hacking writes:

Frege also considers something analogous to what Locke would have called the idea signified by a sign. Frege speaks of the ‘idea’ associated with a word, in contrast to the word’s sense and reference. There has been much philosophy between Locke and Frege, and the word ‘idea’ has not stayed in its place, especially when translated into German as Vorstellung and back again. But enough has been preserved to take the continuation of this translated passage as read:

Hacking then goes on to cite this passage from Frege. Over the years, competing translations of Frege’s works have been published, and the translation of some of his central vocabulary items has become a question. For example, Sinn and Bedeutung have been rendered variously as sense, reference, referent, meaning, and significance. Thus the question of which translation one is reading becomes important. In Max Black’s translation, the text reads:

The reference and sense of a sign are to be distinguished from the associated idea. If the reference of a sign is an object perceivable by the senses, my idea of it is an internal image, arising from memories of sense impressions which I have had and acts, both internal and external, which I have performed. Such an idea is often saturated with feeling; the clarity of its separate parts varies and oscillates. The same sense is not always connected, even in the same man, with the same idea. The idea is subjective: one man’s idea is not that of another. There result, as a matter of course, a variety of differences in the ideas associated with the same sense. A painter, a horseman, and a zoologist will probably connect different ideas with the name ‘Bucephalus’. This constitutes an essential distinction between the idea and the sign's sense, which may be the common property of many and therefore is not a part of a mode of the individual mind For one can hardly deny that mankind has a common store of thoughts which is transmitted from one generation to another.

With Locke, Frege is content to leave the word ‘idea’ somewhat ambiguous. According to Frege, it can include sense-impressions, acts, memories of sense-impressions, memories of acts, and even objects of perception:

We can include with ideas the direct experiences in which sense-impressions and acts themselves take the place of the traces which they have left in the mind. The distinction is unimportant for our purpose, especially since memories of sense-impressions and acts always help to complete the perceptual image. One can also understand direct experience as including any object, in so far as it is sensibly perceptible or spatial.

Yet Frege is clear that ‘sense’ must be distinct from ‘idea’ - even if ‘idea’ is left a bit vague. What is here rendered as ‘idea’ is Vorstellung which had served as a piece of Kantian jargon, and its appearance raises questions about to which extent Frege might be importing Kant’s psychology. For Frege, Kant’s metaphysics might be largely irrelevant, because Frege seems more concerned with logic and language. Frege's word Gedanke is here rendered as 'thought' and would become the topic of another famous essay by Frege. In any case, Frege's main occupations were Sinn and Bedeutung, and ‘idea’ and ‘thought’ received less of his attention. He is clear that Sinn and ‘idea’ were quite distinct:

Hence it is inadvisable to use the word ‘idea’ to designate something so basically different.

The foundational role which Frege played in the beginning of contemporary philosophy consisted in his emphasis upon language and logic, and in his task of clarifying mechanisms by which both work. To be sure, Frege was a mathematician, and much of his work was with an eye toward mathematical uses of language and logic. Yet the philosophical implications of his own work did not escape him. The Fregean flavor of analytic philosophy permeates its various subdivisions. Milton Munitz writes:

The development of analytic philosophy is a central and important aspect of twentieth-century thought. The term ‘analytic philosophy’, as we have remarked, does not designate a single, tightly organized, unified movement whose adherents subscribe to a well-defined body of commonly shared principles. There is much diversity - sometimes sharp antagonism of thought - among the various subgroups or individual thinkers collected under this heading.

In the diversity of contemporary analytic philosophy, Milton Munitz argues, the unifying thread is Frege. Frege is the point of departure: either one agrees with Frege and extends his work, or one disagrees with Frege and argues for some alternative position, or one explores some topic which has come to attention because of Frege.

Yet despite this diversity, the utility of using the label ‘analytic philosophy’ derives from two principle considerations. First, there is enough (even if not total) unity to warrant the use of a common classificatory label for those philosophers whose broad orientation is ‘analytic’ in contradistinction to those falling outside this group. Second, and perhaps more to the point, the movement we are calling ‘analytic philosophy’ has special links to the germinal ideas of Frege. The multiple interconnections and influences among analytic philosophers are illuminated when seen as so many diverse offshoots of Frege’s work. This is not to say that all analytic philosophers are 'Fregeans' in one form or another. This is emphatically not so. Many, to be sure, were directly influenced by Frege. They undertook to assimilate, interpret, and adapt what they found of value in Frege’s work in their own thought. But even among these some found points on which they diverged from or criticized Frege. (Frege himself, for that matter, did not have a monolithic, unchanged set of doctrines to which he adhered.) Nevertheless, within the analytic movement there is by and large a direct line from Frege to other thinkers in which we can note a carrying out of an interpretation or amplification of Frege's themes, doctrinal emphases, and philosophic viewpoint. On the other hand, as we trace the unfolding of analytic philosophy, there are other component movements or individual thinkers whose characteristic theses and claims are best seen as reactions to those who had a more direct or sympathetic relation to Frege’s views. Here the picture gets more complicated as we seek to follow the multiple crisscrossing interconnections. Suffice it to say for the moment that even the latter post-Fregean analytic movements are better understood when seen in terms of their place in relation to the Fregean matrix and starting point. I shall not now attempt to work out the relevant details of this observation, but will do so later at appropriate stages of our exposition. Yet it will be helpful to illustrate, in a preliminary way, the sort of thing I have mind.

Although Frege may be the foundation for contemporary analytic philosophy, he did not arise ex nihilo, as we have seen: he arises, in part, in a Lockean context. Saul Kripke notes that Frege also arise in the setting of John Stuart Mill’s thought about proper names:

Now, what is the relation between names and descriptions? There is a well known doctrine of John Stuart Mill, in his book A System of Logic, that names have denotation but no connotation. To use one of his examples, when we use the name ‘Dartmouth’ to describe a certain locality in England, it may be so called because it lies at the mouth of the Dart. But even, he says, had the Dart (that’s a river) changed its course so that Dartmouth no longer lay at the mouth of the Dart, we could still with propriety call this place ‘Dartmouth’, even though the name may suggest that it lies at the mouth of the Dart. Changing Mill’s terminology, perhaps we should say that a name such as ‘Dartmouth’ does have a ‘connotation’ to some people, namely, it does connote (not to me - I never thought of this) that any place called ‘Dartmouth’ lies at the mouth of the Dart. But then in some way it doesn’t have a ‘sense’. At least, it is not part of the meaning of the name ‘Dartmouth’ that the town so named lies at the mouth of the Dart. Someone who said that Dartmouth did not lie at the Dart’s mouth would not contradict himself.
Even as contemporary philosophers who are staunchly anti-Fregean are nonetheless working in a Fregean context, so also Frege himself was working to some extent in Mill's context. Frege argues directly against Mill. Saul Kripke writes:

But the classical tradition of modern logic has gone very strongly against Mill’s view. Frege and Russell both thought, and seemed to arrive at these conclusions independently of each other, that Mill was wrong in a very strong sense: really a proper name, properly used, simply was a definite description abbreviated or disguised. Frege specifically said that such a description gave the sense of the name.

Mill’s view of proper nouns was that they were directly linked to their referents: that they referred directly, not by means of a Fregean sense. Saul Kripke will side with Mill against Frege on this question:

The modern logical tradition, as represented by Frege and Russell, seems to hold that Mill was wrong about singular names, but right about general names. More recent philosophy has followed suit, except that, in the case of both proper names and natural kind terms, it often replaces the notion of defining properties by that of a cluster of properties, only some of which need to be satisfied in each particular case.

While Saul Kripke embraces Mill’s view of proper nouns, he reject Mill’s view of common nouns - or he rejects what he takes to be Mill’s view of common nouns. Some scholars question whether Kripke understood Mill properly on this point. Stephen Schwartz writes:

Saul Kripke in his revolutionary and influential series of lectures from the early 1970s (later published as the book Naming and Necessity) famously resurrected John Stuart Mill’s theory of proper names. Kripke at the same time rejected Mill’s theory of general terms. According to Kripke, many natural kind terms do not fit Mill’s account of general terms and are closer to proper names. Unfortunately, Kripke and his followers ignored key passages in Mill’s A System of Logic in which Mill enunciates a sophisticated and detailed theory of natural kind terms that anticipates and is in some ways superior to Kripke’s.

Frege’s notion of Sinn was originally formulated as the way in which reference was made to an object. His famous example was the planet Venus, which is known both as ‘the morning star’ and as ‘the evening star’ - the same referent with two different senses. Thus, for Frege, Sinn was determined by a criterion: how one referred to an object. Later Fregeans would formulate Sinn as a set of criteria, from among which several could be chosen. Kripke writes:

The modern logical tradition, as represented by Frege and Russell, disputed Mill on the issue of singular names, but endorsed him on that of general names. Thus all terms, both singular and general, have a ‘connotation’ or Fregean sense. More recent theorists have followed Frege and Russell, modifying their views only by replacing the notion of a sense as given by a particular conjunction of properties with that of a sense as given by a ‘cluster’ of properties, only enough of which need apply. The present view, directly reversing Frege and Russell, (more or less) endorses Mill’s view of singular terms, but disputes his view of general terms.

According to Frege, the Sinn of a proper noun was a compressed description. A proper noun like ‘Aristotle’ contained, argues Frege, in a hidden way, a description like “the teacher of Alexander” or “a student of Plato” - Frege states:

The sense of a proper name is grasped by everybody who is sufficiently familiar with the language or totality of designations to which it belongs; but this serves to illuminate only a single aspect of the reference, supposing it to have one. Comprehensive knowledge of the reference would require us to say immediately whether any given sense belongs to it. To such knowledge we never attain.

Working out the example of ‘Aristotle,’ Frege continues:

In the case of an actual proper name such as ‘Aristotle’ opinions as to the sense may differ. It might, for instance, be taken to be the following: the pupil of Plato and teacher of Alexander the Great. Anybody who does this will attach another sense to the sentence ‘Aristotle was born in Stagira’ than will a man who takes as the sense of the name: the teacher of Alexander the Great who was born in Stagira. So long as the reference remains the same, such variations of sense may be tolerated, although they are to be avoided in the theoretical structure of a demonstrative science and ought not to occur in a perfect language.

While it is proper to view Frege as foundational to contemporary analytical philosophy, it is also proper to view him in the context of Locke and Mill. In this way, contemporary philosophy is seen in a way which emphasizes its continuity with the past.