DiLeo, J. (1991) Peirce's Haecceitism. Transactions of the Charles S Peirce Society 27(1): 79--109. Dave Harris Peirce used the term haecceity to discuss individuation, and there are connections with these more general notion of the categories.  Like Deleuze, he borrowed from Scotus. The context was the debates in the early 14th century on the ontological status of universals.  Plato had argued that there were universal natures independent of both the characteristics of particulars and of conceptions of the general in the mind.  Scotus agreed with Aristotle that essential natures must be connected to particulars in reality, as some kind of 'metaphysical constituent of the things whose natures they are' (81).  However, particulars had to have further distinguishing characteristics.  This led to 'a principle of individuation that will allow for distinctions among particulars', and possible candidates for this principle included 'negation, existence, quantity, matter'.  Scotus believed that only individuals actually existed, so their beings had to be investigated in order to end with a hierarchy with God at the summit.  There must be something in the individual which makes it both universal and singular, but this could be neither empirical nor take the form of a category.  Instead, individuals could be best seen as modes of the common nature of individual things, not just found in individuals in existence.  However, we cannot just discover these by examining the 'predicates' [empirical properties?] of actual things, since common nature is a concept, a principle found in the mind—this principle of individuation is haecceitas.  Scotus thought that the way it worked was to 'contract' common nature, which omits the empirical principles of negation and quantity and so on.  The haecceity is not a thing which can be combined with other things, but a principle of differentiation, a special kind of thing: 'the haecceitas of Socrates is "Socratesness", and not "Socrates"' (82).  The principle of differentiation is formally distinct from the nature of the thing, and is based on some conception of objective 'formalitates' [some kind of form or  potential form?] which a thing possesses—in effect, haecceitas is not separate from essence except formally.  What this amounts to is that the human nature of Socrates and his Socratesness 'are not two things, but two realities which are formally distinct and have numerical unity [that is, appear in the same empirical unit]' (83).  Beings are composite things, and haecceitas represents the last stage of concrete existence, something which 'restricts the specific form...and completes it by seeing the being as "this" being'.  At the moment, this quality is known only to god, but it might be knowable by humans in the future, if intellect becomes independent of sense perception.  Having only a limited knowledge empirically of it, it must remain as a logical requirement because we know there are different individuals, although we tend to see this as arising from 'accidental differences as being in different places at the same time, or having different colored hair or eyes'.  However, we cannot generalize to assume that there is only one general form of 'thisness'. Peirce began to get interested at an early stage, although he was aware of the difficulties of seeming to just add some principle to explain phenomena.  It was easier in a way to accept that the principle was surplus [because we already have the usual way to describe individuals as being particular combinations of more general elements, much as sociologist do when explaining a unique biography as a combination of social class, gender, location and the rest?]. However, he saw haecceity as necessary.  The term became a part of his attempt to explain the existence of things.  The first attempts he made involved a list of categories to describe 'a logical analysis of cognition and judgement' (85), which would explain any attempt to classify and object of thought or experience, but which would also be common to every day thinking.  Peirce agreed that the idea was to simplify sensuous impressions to arrive at conceptions which were essential to explain the unified nature of consciousness.  The categorization starts with conceptions of the present which are nearest to sensations [as in sense data].  These are unified by propositions, those which connect predicates to subjects and which therefore imply being.  The proposition "the stove is black" links the substance, the stove, with some quality, blackness, with which it is inseparable.  Blackness becomes a predicate.  The verb 'is' reduces and simplifies the confused nature of sensation.  In this way, propositions always refer to substances and to being, as the only way to apply the predicates.  They also link being to the subject of the proposition, although these were originally separated. Peirce wanted to connect the steps with further basic conceptions or categories, intermediate categories, which he originally saw as 'accidents' (86).  The intermediate categories are, first, 'quality'[specifying a quality of the substance which can be united with it, so as to link being and substance—the quality of blackness belongs to the stove, and since blackness is something that is, being and substance are linked?]; 'relation' [a psychological process whereby qualities are understood by being similar or contrasting to ones that we know already.  This is a key operation in abstraction, where things are referred to their "correlates" in Peircian terminology]; 'representation'[every proposition refers to an 'interpretant', which has the effect of uniting the '"manifold of the substance itself" (87)—enabling us to name the thing as a black stove?]. There is a later modification to this list of categories, derived from quite different methods, ones that dispensed with th the basic conceptions of substance and being.  Instead, we now have something that connects experience and logic.  Peirce's phenomenology produces categories arising from whatever seems or appears to be the case, and these categories are then modified using '" inductive examination of the methods and tentative conclusions of the positive special sciences"'.  We still get similar intermediate categories, but there are changes, a turn to a more empirical approach, arising both from a grasp of the positive sciences and quantification [a development of logic using Boolean propositions -- so says Peitarinin in a very useful piece] , and a residual subjectivism.  The categories themselves become a series of logical relations 'monadic, dyadic, and triadic'.  These are assumed to be universal and to cover all logical relations, including those involved in the sign.  They cover every predicate of the proposition.  They appear in all experiences and statements about things, although one might dominate of any particular time. Peirce says we could change the names of the categories to quality, reaction and mediation, but he now prefers '"Firstness, Secondness, and Thirdness"'(88) because these would avoid confusion as entirely new words.  They refer both to logical classification of relations, and also classification of experience: all phenomena or experience have these 'three modes of being or aspects specifiable under these categories'.  Firstness is a mode of being which is self contained, 'without reference to anything else', simple and without parts, without any element saw relations found in any 'total feeling', something 'indecomposible, irreducible and indescribable, monadic aspect of the phenomenom'.  It is both a possibility and potentiality.  Secondness is an idea of fact, something that resists, something in the here and now that resists our will, as in brute facts.  It is linked dyadically [in opposition to our understandings?].  Its a 'factual character...  consists in pure individuality, excluding both generality (universality) and possibility'(89), with irreducible characteristics.  Thirdness moves from experience to cognition to relate Firstness and secondness, using operations such as 'meaning, representation, mediation, and thought', involving generality and law. Objects are only known through their properties which makes them subject to 'the Identity of Indiscernibles'[one of Leibniz's ideas—good old Wikipedia renders it as saying that if two different objects have all their properties in  common, they are indiscernible].  [We want to avoid this if we are interested in real individuality, so...] propositions that have terms like 'this is black' are ambiguous [could be indiscernible]  unless we can specify the properties of 'this', or examine the actual object.  One way of doing this latter is to see what has gone on with preceding signs, which have already specified the object referred to by 'this'.  Where they are not specific, the signs are considered to be incomplete.  If we tried to spell out all the properties of the object, however, we still leave the possibility that it is not unique, and may have identical indiscernibles.  This problem was remedied by Peirce turning to an understanding of quantification [as above]. This involves claiming that terms like 'this' must refer to 'an existent individual'(90).  Terms like 'this' become signs 'that awaken and direct the attention'.  In particular, the index denotes a thing directly and forces it on our attention without describing its qualities.  Any object denoted by an index has thisness, and '"distinguishes itself from other things by its continuous identity and forcefulness"'.  This object is a haecceity.  This is how things become unambiguous and distinguishable.  We are alerted to them by terms such as 'this, that, here, now', and these terms denote an object rather than any qualities of the object. Peirce turned to Scotus for this conception, and says that the haecceitas is 'much the same as his category of Secondness' (91) in that it forces itself on our thinking.  There's a debate about the exact relationship, but this characteristic is what they have in common.  [I wonder if this is implied in Deleuze and Deleuze and Guattari as well, that the haecceity can produce epiphany precisely because it imposes itself like this and makes us think again].  The term is described as a '"brutal fact that will not be questioned"'(92), pure secondness, producing a '"shock of reaction between the ego and nonego...  The double consciousness of effort and resistance...  Something which cannot properly be conceived"', since our conceptions always involved generalizations and this would then missed the specificity.  However, haecceity does not define Secondness entirely, but is its 'material aspect'.  We can certainly experience the effects of haecceity and appreciate its '"insistency"'.  Thus it arises in experience and only exists in experience, for both Scotus and Peirce.  However, whatever exists is individual for Peirce, and existence always involves reaction to our experience.  We discover individuals when they react against us [and therefore we discover existence?  And the other way around?] It is the only way in which we get close to discovering individuality, since we can never prove it logically.  This means that existence has a dyadic structure, something opposing our experience, something struggling for existence by opposing, resisting or shocking [other things as well as us?  It looks like it means reaction to a {human?} subject].  We only experience it in this form of reaction, as dyadic form. The affirmation of the individuals is a recent development in Peirce, as is his existence that particulars and universals 'have different modes of being' (94), secondness and thirdness respectively.  There are also different kinds of existence, of actions or volitions, of human and other forms of time, of fiction or art -- and other possible universes.  Each of these different kinds 'is to be understood as an example of haecceity' (95), because they all offer a existence and individuality, 'and thinghood'.  They all involve something other, not ego, in opposition to understanding. There's also a relationship with space [a dictionary entry by Peirce suggests that any portion of space can be an individual, no matter how extended, because space itself can individualize.  Logically, different spaces for locations will always differentiate otherwise indiscernible objects.  Space therefore becomes '"nothing but the institutional presentation of the conditions of reaction, or of some of them"'].  Space can be considered to be some underlying law like continuum and thus to possess Thirdness, but it must also be capable of being individuated.  As usual, we look to whether it is capable of reaction [in this case a reaction to the suggestion of indiscernibility?].  Time does this too [?] [The argument seems to run back woods in suggesting that because haecceitism is necessary, so a spatial dimension is necessary, extension in space, which 'allows for things to have identical properties' (96) while not being identical.  Indeed, persistence or continuity through time and space makes something distinct from everything else.  This means that haecceity is not dependent on the properties of an object, nor any qualities as such, since these can always be shared with indiscernibles. Haecceity could be internal or external, despite the fact that we usually experience it as something external, factual.  However, we need to precede further to make sure, using various '"tests of externality"' (97), to infer haecceity in contrast to the usual way in which it is detected by perception.  There may be some ambiguity here, also found in the notion of Secondness, which seems to be present directly to perception, as well as being known through interpretants.  In this way, Peirce becomes a realist, believing in existence as well as being and reality.  While reality is not dependent on thought, existence '"means reaction with the environment"'. That we can grasp haecceity in experience, in a way that does not involve concepts, experience must consist of events which are non qualitative.  It means that things do not just depend on having a set of properties or qualities—haecceity is not a property and thus cannot be abstracted from a thing.  However, there remained a possibility that haecceity could at least confer qualitative or descriptive elements to experience.  However, Peirce argues that the particularity of the facts themselves determines whether or not they possess qualities.  The same applies to individuals [the alternative seems to involve some challenge to the principle of contradiction and excluded middle—pass, 98] Here, Peirce is rejecting Scotus and the notion of contraction of, natures into individuals—it is too nominalistic for a pragmatist.  What this means is that Secondness cannot be reduced to a combination of Firstness and Thirdness, nor can Thirdness be contracted to Secondness: individuality and haecceity produce secondness.  Perception must be separate and essential to epistemology.  [?]. For Peirce and his 'exact logic' [see Pietairin again --looks a bit like a proposition needing to spell out exactly how its terms are defined and specified, a bity like a closure principle in programming] , individuals can only be distinct from one another by being haecceities; by having different qualities in themselves; by being in 1 to 1 correspondence to individuals that are distinct from one another in the first two senses.  It is clear that he values the first, and owes a debt to Scotus. Haecceitism is found in modern philosophies [although Deleuze is not mentioned], 99-100. Peirce's late work is interesting in developing a family of logical diagrams: alpha for systems referring to propositional logic; beta dealing with the logic of quantification; gamma claiming to represent logical relations in general.  The first two deal with the 'actual existent world'(100), but the latter invokes the notion of other possibilities, other universes, possible worlds, the logic of the possible or modal logic, relating to a logical space, and this is been developed by subsequent philosophers. The connection between these developments and haecceitism is a matter of debate.