## 1. Life



Almost nothing is known about the life of Thomas of Erfurt except that
he was active as a teacher and philosopher in the first quarter of the
fourteenth
 century.[1]
 Presumably, he came from the city of Erfurt in present-day Germany.
His work shows the influence of the Paris Arts Masters Radulphus Brito
(ca. 1270-1320) and Siger of Courtrai (ca. 1280-1341),
which suggests that he was educated and perhaps also taught at the
University of
 Paris.[2]
 Later documents associate him with the school of St. Severus and the
*Schottenkloster* of St. Jacob at
 Erfurt.[3]
 His most famous grammatical text, *De modis significandi* (On
the Modes of Signifying) was known by 1310 and was already being
commented upon by 1324. It is possible that he returned to Paris a
number of times over the course of his academic career, although there
are no records attesting to this.



Some copies of *De modis significandi* attribute the work to an
early fourteenth-century English cleric named Thomas of Occam, but
scholars have been skeptical about this because it occurs in just a
handful fifteenth-century
 manuscripts.[4]
 The vast majority of the manuscript evidence, and all of the earliest
witnesses, refer to its author as Thomas of Erfurt.


## 2. Writings



Six works have been attributed to Thomas of Erfurt. In addition to the
aforementioned grammatical treatise, whose full title is *Tractatus
de modis significandi seu Grammatica speculativa* (ed.
Bursill-Hall
 1972),[5]
 there are four short *expositiones*, or literal commentaries:
on Porphyry's *Isagoge*, Aristotle's *Categories*,
Aristotle's *De interpretatione*, and the anonymous *Liber
sex principiorum* (Book of Six Principles). Finally, there is a
very brief work of mnemonic verses for teaching grammar to schoolboys,
*Commentarius in carmen 'Fundamentum puerorum'*
(ed. Gansiniec 1960), although its editor believes that it is actually
an anonymous abridgement of *De modis significandi*. In any
case, Thomas's reputation derives from *De modis significandi*,
which remains his only work to have been studied in detail.



*De modis significandi* proved to be so popular that it became
the standard (and later, the representative) text for the Modist
tradition (see next section), surviving in over 40 fourteenth- and
fifteenth-century manuscripts. A printed edition appeared in the late
fifteenth century that was reprinted a remarkable 11 times before its
'definitive' reprinting in Luke Wadding's 1639 edition of
the complete works of Duns
 Scotus.[6]


## 3. Modism



Thomas of Erfurt belonged to an interesting though somewhat obscure
group of late thirteenth- and early fourteenth-century philosophers
known as the speculative grammarians or *Modistae*. The term
'speculative grammarian' is ambiguous because it is also
used by historians of medieval philosophy to refer to twelfth-century
Parisian grammar masters such as William of Conches, Peter Helias, and
Ralph of Beauvais, who systematically revised the ancient grammars of
Donatus and Priscian -- textbooks used to teach Latin to
schoolboys -- to produce a universal
 semantics.[7]
 The two groups are related, as it turns out, since these latter-day
grammarians adopted many of the theories as well as the universalizing
tendencies of their twelfth-century predecessors. Foremost among them
was the theory of the *modi significandi*, or modes of
signifying. The term '*Modistae*' or
'Modist' properly refers to the later group.



There was already a grammatical concept of the *modi
significandi* by the time the first *Modistae*, Martin of
Dacia and Boethius of Dacia, appeared in Paris sometime before
 1270.[8]
 Originally, the idea referred to the different ways in which a word
or expression (*dictio*) is able to signify something. Words
themselves are the product of a primary act of imposition by which a
particular utterance is connected to some thing or property of a
thing, the utterance providing the matter, which is said to be
'informed' by the act of imposition. The word acquires its
*modi significandi* through a second act of imposition encoding
all of the general syntactic roles it can play in connection with
other words and expressions, such as the various parts of speech it
can fulfill (e.g., noun, verb, adverb) and the grammatical forms of
these parts (e.g., the gender, number, and case of nouns; the tense
and mood of verbs). These modes are said to cause the various lexical
forms exhibited by the word in spoken and written languages. Thus,
Latin uses the word '*canis*' to signify what
English speakers mean by 'dog', but the same modes of
signifying determine their function as singular and as
 nouns.[9]
 We might think of *modi significandi* metaphorically as hooks
or fasteners on a word because they reflect its potential for
combination with other words in propositions and other grammatically
well-formed constructions.



It is easy to see how such an account of meaning could lead to a
*bona fide* theory of grammar, what Jan Pinborg called
"the first systematic syntax developed in western
 linguistics".[10]
 Indeed, speculative grammarians of both periods have attracted the
attention of linguists and philosophers
 alike.[11]
 But the stakes were higher for the *Modistae* because the
influx of Aristotle's writings on metaphysics and natural philosophy
in the late twelfth and early thirteenth centuries forced everyone to
think in terms of a new paradigm of knowledge. Could grammar be
reconceived as the science of language (*scientia
sermocinalis*)? The question here was whether grammar could count
as an Aristotelian speculative science, i.e., whether it is
demonstrative in the sense of being a knowledge-producing activity
ordained by a single subject whose principles are universal and
 necessary.[12]
 Concerns of this sort clearly underlie Boethius of Dacia's appraisal
of traditional grammar:



> 
> subjects in which a demonstrative mode of knowing is possible are
> seldom taught in a demonstrative way, but descriptively [*sed modo
> narrativo*] ... That is why Priscian states many conclusions
> for which he offers no reasons, but merely the authority of ancient
> grammarians. Accordingly, he does not teach, for only those who offer
> reasons for what they say are
>  teachers.[13]
> 



Thomas of Erfurt indicates in the opening lines of *De modis
significativis* that he aims to be one of these teachers:



> 
> *The rationale of the method*. Since in all science, to
> understand and to know come about from the knowledge of principles, as
> is written in I *Physics*, text comment 1, therefore, wishing
> to have knowledge of the science of grammar, it is primarily necessary
> for us to dwell upon all of its primary *per se* principles of
> which modes are the modes of signifying. But before knowledge is
> sought after in the particulars, there are certain things to be set
> out in advance in general, without which it is not possible to have
> the fullest understanding of them. (*DMS*, Preamble;
> Bursill-Hall: 1)
> 



For *Modistae* such as Boethius of Dacia and Thomas of Erfurt,
the proper subject of grammar is well-formed, significant speech
(*sermo congrue significativus*), the principles of which are
expressed in the *modi significandi*.



But this is where things get interesting, for the *Modistae*
also understood the theory of the *modi significandi* to
involve claims about the nature of thought and reality. The problem
with Priscian, as twelfth-century grammarians had pointed out, is that
he said nothing about what *causes* the different parts of
speech. Hence the need for a theory of the *modi significandi*.
But the *Modistae* saw that this could only be part of the
answer, for grammar is a linguistic phenomenon, and linguistic
phenomena must have a cause within the natural order of things.
Therefore, to complete the explanation, they argued that the formal
structure of the *modi significandi* owes its existence to
*modi intelligendi*, or modes of understanding, which in turn
are caused by *modi essendi*, or the modes of being a thing can
exhibit outside the mind.



The heart of the Modist project is the assumption that there is a
triadic or parallel relationship between word, concept, and thing.
Meaning is based proximately on understanding but ultimately on being.
According to Thomas of Erfurt:



> 
> *Every mode of signifying is from some property of the thing*.
> Concerning the second thing to be noted, that since such notions or
> modes of signifying are not fictions, it must be that every mode of
> signifying radically originates from some property of the thing. This
> is plain thus: since the intellect, in order to signify, imposes the
> voice under some mode of signifying, it considers the property itself
> of the thing from which it originally drew the mode of signifying;
> this is because the intellect, since it is a passive power
> indeterminate of itself, does not advance to a determinate act unless
> it is determined from another source. Whence since it imposes the
> voice in order to signify under the determinate mode of signifying, it
> is necessarily moved by a determinate property of the thing; therefore
> some property of a thing, or mode of being of a thing, corresponds to
> any mode of signifying. (*DMS*, 2.4; Bursill-Hall: 3)
> 



Note the phrase, "since such notions or modes of signifying are
not fictions." The *modi significandi* could not play any
causal role in determining the parts of speech, nor the corresponding
*modi intelligendi* in determining the *modi
significandi*, nor the *modi essendi* in determining the
*modi intelligendi*, unless they all actually exist. Here the
*Modistae* drew on the Aristotelian idea that although spoken
sounds and written marks differ from language to language, "what
these are in the first place signs of -- affections of the soul
-- are the same for all; and what these affections are likenesses
of -- actual things -- are also the same" (*De
interpretatione*
 1.16a3-9).[14]
 Likewise, the ordering of modes was intended to replicate the
ordering of disciplines in an Aristotelian speculative science: just
as psychology, the study of moving things *qua* animate, is
subordinate to physics, the study of things *qua* moving, and
physics is subordinate to metaphysics, the study of things
*qua* existing, so the principles of grammar (*modi
significandi*) are derived from mental acts of signifying
(*modi intelligendi*), which reflect the way things really are
(*modi essendi*).



Tidy conceptual schemes tend to become less so when confronted with
the empirical facts, and the *Modistae* spent a great deal of
time trying to explain recalcitrant linguistic data. After sketching
the origins of the *modi significandi* in the first chapters of
his treatise, Thomas immediately considers a few objections: how can
'goddess [*dea*]' be signified with a feminine
noun, which connotes passivity? Answer: a mode of signifying need not
always be drawn from the thing signified, for sometimes it "can
be taken from the property of the thing of another utterance;"
thus, when we say 'in God', we do not mean to attribute
passivity to God, who suffers not, but only to "imagine him as
if being affected by our prayers." When we use a passive or
feminine mode of signifying in relation to God, what we are really
doing is signifying our own passive or feminine conception of some
*other* thing that *is* a genuine recipient, i.e.,
something that does correspond to a determinate mode of being
*qua* recipient, and then imposing the same word to signify
God. In the same way, we impose names on things we cannot sense via
the properties of sensible things, thereby attributing "active
modes of signifying to their names" (*DMS* 2.5;
Bursill-Hall: 4).



But what about words signifying fictions, such as
'chimera', or privations, such as 'blindness'?
These do not correspond to any mode of being, active or passive, since
they signify nothing (i.e., no thing). According to Thomas, the active
modes of signifying chimeras "are taken from the parts from
which we imagine a chimera to be composed, which [fiction] we imagine
from the head of a lion, the tail of a dragon, etc"
(*DMS* 2.5; Bursill-Hall: 4). Names of privations, on the other
hand, "designate the modes of understanding of privations, which
are their modes of being, through their own active modes of signifying
about privations". The idea here is that 'blindness'
corresponds to our positive concept of sight *qua* absent,
which enjoys a positive *modus essendi* in our intellects.
Thus, "although privations are not positive beings outside the
soul, they are nevertheless positive beings in the soul ... and
since the understanding of them is their being, therefore, their mode
of understanding would be their mode of being" (*DMS*
2.6; Bursill-Hall: 4). Blindness outside the soul cannot cause any
conception of itself *per se*, since blindness *per se*
does not exist, and what does not exist cannot be the cause of
anything. Accordingly, when we say, 'Homer was a blind
man,' the word 'blind' actively signifies the
passive mode of understanding something as being without sight, and
owes its semantic function to the way its corresponding concept is
understood. In the case of concepts that are neither fictions nor
privations, these modes of understanding are further determined by
their corresponding modes of being, i.e., by actual substances and
properties outside the soul.



For the *Modistae*, then, the words 'chimera' and
'horse' differ, but only in terms of the complexity of
their underlying modes. Thomas follows Siger of Courtrai in
distinguishing between active and passive *modi
significandi*/*modi intelligendi* to explain the difference
between the act of signifying/understanding (materially construed as a
property of the utterance/concept) and the object signified/understood
(materially construed as a property of the thing
signified/understood). The fact that nothing answers to the name
'chimera' simply does not matter. Modism was a theory
about meaning (*significatio*) of a word as opposed to its
reference (*suppositio*), and reference was regarded as
something determined by logicians. Besides, if grammatical truths
are universal and necessary -- i.e., if there really is a science
of grammar -- then they cannot be altered by the fact that there
are no chimeras. It is the assumption that some palpable phenomenon
must underlie every grammatical truth, causing it to be the way it is,
which guides Thomas's discussion in the remainder of the treatise,
which soon moves on to more practical matters such as the different
parts of speech ('*Etymologia*') and their syntax
('*Diasynthetica*'). Included in the latter are the
concepts of *constructio* (the syntactic joining of one word to
another), *congruitas* (the proper formation of such
constructions), and *perfectio* (the proper formation of
complete expressions).



Modist explanations of semantic phenomena tended to be extremely
complicated. Indeed, if we consider the manifold ways in which a word
can be a signifier together with its potential for combination with
other words in expressions, there could be infinitely many *modi
significandi* -- a proliferation of modes repeated all over
again at the level of *modi intelligendi*. Philosophers today
think of Meinong's theory of objects as a paradigm of ontological
incontinence. These philosophers have never met the *Modistae*,
who would make even Meinong seem parsimonious. But in a way this is
unfair, of course, since the *Modistae* were not ontologists
and had no interest in the ontological consequences of their theories.
They were first and foremost concerned with the phenomenon of
linguistic meaning, and invoked whatever entities they felt could best
explain what they observed.



Thomas's *De modis significandi* was the last work to develop
Modist doctrine to any significant
 degree.[15]
 Its clarity and relative brevity led to its adoption as the standard
Modist text in medieval universities, replacing the earlier *Modi
significandi* of Martin of Dacia. But by 1330 and for reasons that
remain unclear, Modism had completely disappeared from Paris, pushed
aside by the more powerful and comprehensive approach of the
*Summulae de dialectica* of John Buridan (ca.
 1300-1361).[16]
 Modism was never able to overcome certain difficulties, such as its
refusal to recognize extra-linguistic context, as a result of which it
could not explain how meaning can be communicated via incongruous or
imperfect
 expressions.[17]
 But the most likely reason for its demise was that it no longer
provided satisfying explanations of the phenomena it was supposed to
explain. The one thing it could do, provide an account of the syntax
of Latin grammar, could be achieved more economically by other means.
In addition, the theory became absurdly complicated in order to save
the phenomena of the *modi significandi*, suggesting that the
*modi* finally collapsed under their own weight, like so many
Ptolemaic epicycles.


## 4. Influence



Thomas of Erfurt's *De modis significandi* has enjoyed more
attention than it might otherwise have received thanks to its early
misidentification as a work of Duns
 Scotus.[18]
 As a result, it was printed along with authentic works on logic in
volume 1 of Luke Wadding's seventeenth-century edition of the
*Opera Omnia* of Duns Scotus (Lyons 1639), and again in the
nineteenth-century reprint of Wadding by Juan-Luis Vives (Paris
 1891).[19]
 Until recently, the Wadding-Vives edition was the definitive
source for the works of Scotus, so anyone consulting it would have
associated *De modis significandi* with
 him.[20]
 Complicating the story somewhat is the fact that Scotus was
influenced by Modism early in his career, though this was probably due
to his exposure to Modist authors such as Simon of Faversham and
Andrew of
 Cornwall.[21]
 It is unlikely that he was influenced by Thomas of Erfurt, because
*De modis significandi* did not circulate widely until after
Scotus's death.



Thomas of Erfurt had a famous contemporary, Meister Eckhart (c.
1260-1328), the German Dominican philosopher and mystical
theologian. Meister Eckhart was not only present in Erfurt at roughly
the same time as Thomas, but also lived only a few streets away. It
seems incredible that they could not have known each other personally
and academically, though there is no explicit evidence that they did.
Despite this, there is indirect evidence that Meister Eckhart was
influenced by Thomas in his grammatical approach to interpreting
scripture. Their intellectual relationship is the subject of a recent
volume of
 essays.[22]




One of the many later figures to have unwittingly admired Thomas was
the American philosopher, Charles Sanders Peirce (1839-1914),
who regarded Duns Scotus as a fellow traveler in metaphysics and whose
own semiotic theory resembles the Modist program in certain
 respects.[23]
 Peirce quotes verbatim the first six chapters of *De modis
significandis* in an 1869 lecture comparing (what he took to be)
the views of Duns Scotus and William of Ockham on names and
signification. But the lecture is introductory in character, leaving
it uncertain whether Peirce fully appreciated what was at stake in
Modistic grammar, rather than viewing it, say, as some sort of
linguistic addendum to Scotus's
 metaphysics.[24]



Another figure so influenced was Martin Heidegger, whose
*Habilitationsschrift* was published in 1916 under the title,
*Die Kategorien- und Bedeutungslehre des Duns Scotus*. This
book is only beginning to be studied by Heidegger scholars, which is a
pity because it is really about Heidegger's own project of advancing
the Husserlian notion of *a priori* grammar. A work of
historical scholarship it is not. In what now seems a classic
understatement, the historian of medieval philosophy Martin Grabmann
wrote of this book in 1926, "Martin Heidegger has demonstrated
the continuity of the *Grammatica speculativa* hitherto
attributed to Duns Scotus with the terminology and overall
intellectual outlook of Husserl, so that the structure and
distinctiveness of the medieval original is somewhat
 obscured".[25]
 In his defense, Heidegger never pretends to be doing history of
philosophy in *Die Kategorien- und Bedeutungslehre des Duns
Scotus*. On the contrary, he states at the beginning of Part II
that he is mostly interested in exploring the implications of *De
modis significandi* for the broader theory of meaning, and that he
is following scholarly consensus in attributing it to Duns
 Scotus.[26]



In 1922, however, Grabmann conclusively demonstrated that it was
Thomas of Erfurt who wrote *De modis significandi*, not Duns
 Scotus.[27]
 So the claim that Heidegger wrote his *Habilitationsschrift*
on Duns Scotus is only partly true. The first half, *die
Kategorienlehre*, is correctly addressed to Scotus's theory of the
categories as developed in his authentic commentaries on Porphyry's
*Isagoge*, and Aristotle's *Categories* and *De
sophisticis elenchis*. But the second half, *die
Bedeutungslehre*, is based almost entirely on Thomas of
 Erfurt.[28]



For more recent influence, we need look no further than Jacques
Derrida, who mentions Thomas of Erfurt (this time dressed as himself)
in connection with the old Peircean idea that logic is a branch of
semiotics: "As in Husserl (but the analogy, although it is most
thought-provoking, would stop there and one must apply it carefully),
the lowest level, the foundation of the possibility of logic (or
semiotics) corresponds to the project of the *Grammatica
speculativa* of Thomas d'Erfurt, falsely attributed to Duns
 Scotus" (1976: 48).
 What impresses Derrida is not so much the reduction of logic to
grammar as the deconstructive potential of Husserl's phenomenology of
signs. The idea of deconstructing the science of language would have
struck Thomas as absurd, of course, though he probably would have felt
some affinity with the highly variegated notion of the sign in modern
semiotics.