Prescission (also spelled: precision, prescision, precission) is a method used by Peirce to separate concepts and ideas from one another and to find hierarchical relationship of dependence among them. In particular, prescission is applied in those cases in which two objects cannot be imagined separately (that is, we cannot form a mental image of one object without also forming the image of the second), but we can nonetheless suppose one without the other (that is, we can think of it as logically or metaphysically possible without the other) (cf. W 5:238, 1885; EP 2:270, 1903). Peirce locates the historical origin of this method in medieval scholastic philosophy, and more precisely in Duns Scotus’ praecisio (cf. DPP 2:323, CP 1.549n., 1902). Prescission is of fundamental importance within Peirce’s system because it is used to identify relationships among the three fundamental categories. It is a method that Peirce continues to use throughout his entire career. Insofar as the doctrine of categories affects how Peirce accounts for relationships among different elements and disciplines within his system, prescission arguably identifies relationships at various levels in Peirce’s thought.

Prescission as contrasted to other methods of separation and abstraction

When Peirce introduces prescission as a particular method of philosophical analysis, he often contrasts it with other two methods of separation of concepts and ideas: dissociation and discrimination. The three methods are presented as identifying distinctions of increasing strength, where discrimination and dissociation result in the weakest and the strongest separation respectively. This is how Peirce introduces these methods in “On a New List of Categories” (hereafter “New List”):

While the difference among the three methods is presented as a matter of degree, there are certainly also important differences in the kinds of differentiation they operate. Accordingly, Peirce describes dissociation as chiefly psychological in character (cf. DPP 2:323; CP 1.549n., 1902). It ascertains the possibility of forming a mental image of a determinate object without simultaneously forming the image of another. By contrast, discrimination seems to be first of all semantic, since Peirce explicitly says that it draws distinctions in meaning. This leaves open the question concerning which kind of distinction is obtained by means of prescission. It seems right to suggest that the latter focuses on logical relationships between concepts and ideas, insofar as Peirce in 1903 maintains that it shows when one element is “logically possible without the other” (EP 2:270, 1903). This is probably what Peirce has in mind when he claims that prescission shows when an object can be supposed without another (cf. W 5:238, 1885; EP 2:270, 1903). Having said that, the way in which Peirce presents the operations of all three methods often has psychological overtones. In the “New List” they are introduced as different methods of “mental separation,” while around 1905 Peirce still describes them as involving three different “modes of mental analysis” (cf. MS 294:69, 1905). A possible way to account for this fact is to say that all three methods, including prescission and discrimination, can be used to investigate mental phenomena. This claim finds confirmation in the circumstance that Peirce later considers these methods to be essential tools in his phenomenology or phaneroscopy (cf. MS 499s, 1906). However, the fact that these methods can be used to investigate mental phenomena is compatible with the claim that the relationships uncovered by prescission and discrimination are not first of all psychological.

It is here interesting to note that in 1866, in a manuscript which contains preparatory materials for the “New List,” Peirce draws a distinction among dissociation, prescission and discrimination by claiming that prescission is the only one method that can display nonreciprocal relationships between its objects: “If A can be discriminated or dissociated from B, B can also be separated from A, in the same mode. But precision is not thus reciprocal; but on the contrary it is frequently the case that though A cannot be prescinded from B, B can be prescinded from A” (W 1:519, 1866). This makes clear that Peirce developed his interest for prescission because he thought that it was the best tool for uncovering nonreciprocal relationships between concepts and ideas. In this way, concepts could be hierarchically ordered according to relationships of logical dependence (cf. Gava 2011b; Gava 2014, ch. 1, 5; Zeman 1983, 294). However, soon after 1866 Peirce started to doubt that dissociation and discrimination are always reciprocal. Accordingly, in the “New List” we still find him claiming that “prescision is not a reciprocal process” (W 2:51, 1867), but here he does not say explicitly that dissociation and discrimination are reciprocal. As far as dissociation is concerned, Peirce gives in 1885 an example of two ideas which are not reciprocally dissociable: “we can imagine Red without imagining Blue, and vice versa; we can also imagine Sound without Melody, but not Melody without Sound. I call this kind of separation Dissociation” (W 5:238, 1885). Moreover, an example that he already uses both in the 1866 manuscript quoted above and in the “New List” suggests that discrimination can in fact be nonreciprocal. Peirce maintains that red cannot be discriminated from colour, while it can be discriminated from blue (cf. W 1:518, 1866; W 2:50-1, 1867). Insofar as, as we have already seen, Peirce also stresses that discrimination focuses on semantic relationships, scholars have suggested that it determines relationships of analytic entailment. Thus, while colour is analytically entailed in red, this is not the case for red with respect to blue or vice versa (cf. Hookway 1985, 97). According to this understanding of discrimination, colour seems to be discriminable from red, insofar as the latter concept is not analytically entailed in the former. But insofar as red is not discriminable from colour, this would imply that discrimination can display nonreciprocal relationships between concepts as well.

While the possibility of nonreciprocal relationships does not appear to constitute a concern for Peirce in the case of dissociation, describing discrimination as a method which can identify nonreciprocal relationships seems in fact to be problematic. For Peirce maintains that if it is possible to establish a nonreciprocal relationship of prescission between two concepts, it must at least be possible to reciprocally discriminate the two. In other words, if it is possible to prescind A from B, while it is not possible to prescind B from A, it must at least be possible to discriminate A from B and vice versa (cf. EP 2:270, 1903; MS 284: 76-7, c.1905). Now, allowing nonrecipocal relationships of discrimination seems to violate this latter requirement for those cases in which nonreciprocal relationships of prescission are coextensive with nonreciprocal relationships of discrimination. If A is prescindible from B and not vice versa, A is necessarily also discriminable from B. However, if this relationship of discrimination between A and B were nonreciprocal, Peirce’s requirement that if A is prescindible from B, B must at least be discriminable from A would fall (cf. EP 2:270, 1903). This is easy to see if we take into consideration once again the relationship between colour and red. We have seen that according to Peirce red is not discriminable from colour (cf. W 1:518, 1866; W 2:50-1, 1867). We have also seen that if we understand discrimination as identifying relationship of analytic entailment, colour should be discriminable from red. But colour seems to be also prescindible from red, insofar as it is “logically possible” or “supposable” without the latter. This would mean that while colour is prescindible from red, red would not be discriminable from colour as Peirce requires when addressing the relationship between prescission and discrimination in general.

This might be especially problematic if we take into consideration the application of prescission and discrimination to the determination of the relationships among the three categories. For Peirce stresses that while the simpler categories are prescindible from the more complex one, the latter must at least be discriminable from the former (cf. MS 284:76-7, c.1905). But it is not clear if this would be possible if discrimination identified (sometimes nonreciprocal) relationships of analytic entailment. In fact, it might be argued that the simpler categories are analytically entailed in the more complex one, so that they would not be discriminable from the former, while the contrary operation would be possible. According to this understanding of discrimination we would then be unable to say that while the simpler categories are prescindible from the more complex ones, the latter can be discriminated from the former.

I submit that it would be better to understand discrimination in a more modest way, one according to which the relationships it discovers would be, at least for the most part, reciprocal ones. Discrimination would thus simply identify differences in meaning, where if A and B are reciprocally discriminable, this means (according to Peirce’s pragmatic maxim) that we would experience different consequences when these concepts applied. Peirce suggests something along these lines when he argues that discrimination shows that the “conditions” for A and B to apply are different (cf. MS 284:73, c.1905). The only cases in which two concepts were not discriminable would then be when they are synonymous. According to this understanding, red would be discriminable from colour and vice versa. This is of course in contrast to what Peirce explicitly claims in the “New List,” but in fact, at least to my knowledge, Peirce does not stress that red is not discriminable from colour after 1867.

Prescission would thus be the method responsible for identifying nonreciprocal relationships of analytic entailment, like the one between red and colour, but it would not be limited to that. There are cases in which A is not analytically entailed in B and nonetheless B cannot be prescinded from A. According to Peirce, this is the case for space with respect to colour, so that even though space is not analytically entailed in the concept colour, colour is not prescindible from space (cf. W 1:518-19, 1866; W 2:51, 1867) . Prescission seems thus able to display strictly logical relationships of dependence, or lack thereof – and this fits very well Peirce’s claim that prescission shows when an element is “logically possible” without the other. However it goes beyond simple logical entailment and also uncovers what might be called relationships of metaphysical dependence, as in the case of colour with respect to space. The dependence in question seems here to be metaphysical because we cannot think of colour as a possible object without thinking that it would occupy some space. Dissociation instead just displays relationships between concepts and ideas that belong to our psychology.

In the passage of the “New List” quoted above Peirce uses prescission and abstraction as synonymous terms. However, he will later distinguish between prescission and abstraction proper, which he also calls precisive and hypostatic abstraction respectively (cf. CP 2.364n., 4.235, 5.449, EP 2:352; NEM 3:918). We have seen that prescission is the capacity of regarding an object as logically – or metaphysically – possible without another. By contrast, hypostatic abstraction is responsible for the creation of an ens rationis (cf. EP 2:352, 1905. According to Peirce, the latter is the result of a process that turns “predicates from being signs that we think or think through, into being subjects thought of” (CP 4.549, 1906). This operation is also described as “that process whereby we regard a thought as a thing” (EP 2:394, 1906). An example that Peirce repeatedly uses to illustrate the working of hypostatic abstraction is the transformation of the sentence “opium puts people to sleep” into the sentence “opium has a dormitive virtue” (cf. NEM 4:160-2,  1903). This operation, which is famously ridiculed in Molière’s Le malade imaginaire, is in fact an essential and powerful tool we often use in our reasoning (cf. Zeman 1983; Stjernfelt 2007, ch. 11). Peirce maintains that it is in mathematics in particular that hypostatic abstraction displays its major merits. However, also in the opium case it can be shown that it is not only a play with words. For if we did not move from an inductive conclusion such as “opium puts people to sleep” to “opium has a dormitive virtue,” we would not be able to start an inquiry and look for that something that would explain why opium puts people to sleep (cf. NEM 4:161, 1903).

Prescission and the categories

Now that we have a clearer idea of what prescission is and of what distinguishes it from other forms of mental separation and from hypostatic abstraction, we can look more closely at the way in which Peirce puts this method to use. The central and most important application of prescission lies in Peirce’s account of the three fundamental categories and of their relationships. Prescission is here used to show that the categories are fundamental elements of our experience and thought, so that if we take into consideration our thought and experience in general, they cannot be prescinded from the categories, that is, the categories are essential elements in order to account for them. But prescission is also used to determine in which relation the categories stay to one another.

The clearest and most extensive account of how prescission is used to sort out the relationships existing among the categories is probably given in the “New List.” Here Peirce tries to identify the universal conceptions that are necessary  in any attempt to “reduce the manifold of sensuous impressions to unity” (W 2:49, 1867). Peirce will later abandon this Kantian-sounding formulation, but he will continue to hold that the categories are fundamental elements of thought and cognition. I will avoid going into the details of Peirce’s argument in the paper and focus on the role played by prescission instead. Peirce identifies five categories that are necessary for accomplishing the task of reducing a manifold of sense to unity. These are:

Being and substance here identify the two extremes in the process of bringing the manifold of sense to unity, where substance represents the way in which the manifold is first given as something present in general, while being is the unity introduced by a proposition, and in particular by its copula (cf. W 2:49-50). Quality, relation and representation, which will later become firstness, secondness, and thirdness, are the intermediate categories that are necessary to apply the unity of the copula to substance. Roughly, Peirce’s line of argument rests on the fact that in order to apply the unity of the copula to a substance you need a predicate which attributes a quality to that substance (cf. W 2:52). But we can discern a quality only by setting it in contrast with another quality (cf. W 2:53).  However, when we contrast a quality to another, we do it by comparison, where comparison always requires a mediating representation, which Peirce calls interpretant (cf. W 2:53-4). In this way, it is shown that quality, or reference to a ground, relation, or reference to a correlate, and representation, or reference to an interpretant, are necessary to apply the unity of being to substance.

What is interesting for our purposes here is to see how prescission is able to sort out logical relationships of dependence among these categories (cf. Gava 2014, ch. 1, 5). For even though the categories cannot be dissociated from one another – according to Peirce, psychological investigation shows that we cannot form the idea of a quality without having the idea of a correlate, and of a correlate without the idea of an interpretant – they can stay in relationships of prescission. Accordingly, each category can be prescinded from the categories that are more complex than it, where the contrary operation is not possible. As a consequence “[r]eference to a ground cannot be prescinded from being, but being can be prescinded from it,” “[r]eference to a correlate cannot be prescinded from reference to a ground; but reference to a ground may be prescinded from reference to a correlate” (W 2:53), whereas “[r]eference to an interpretant cannot be prescinded from reference to a correlate; but the latter can be prescinded from the former”  (W 2:54). In this way, prescission is able to show that each category is in fact a fundamental conception, insofar as even though the simplest categories cannot constitute an independent mental content in absence of more complex categories, they can nonetheless be prescinded from them, while the fact that the more complex categories cannot be prescinded from the simpler ones shows the fundamentality of the latter for even making sense of the former.

Peirce will later abandon the strategy of derivation of the categories of the “New List” and will instead identify the categories, first, as fundamental and irreducible logical relations in the logic of relatives (cf. W 5:243, 1885) and, second, as fundamental elements of every mental phenomenon in his phenomenology or phaneroscopy (cf. CP 1.286, c.1904). While substance and being are not listed any more among the fundamental categories and we only find firstness, secondness, and thirdness, prescission continues to be a fundamental tool for both the logic of relatives and phaneroscopy.

Prescission in phaneroscopy

The logic of relatives shows the fundamentality of the categories as irreducible relations at a purely logical level. The task of phaneroscopy is instead that of showing how the categories are in fact essential elements for making sense of our actual mental experience. Prescission remains a fundamental method of analysis for addressing the relationships among the categories at both levels. Around 1905 Peirce thus contends:

Prescission is however important four understanding the method of phaneroscopy in another relevant way. For it can show that while our mental experience in general cannot be prescinded from the categories, the categories can instead be prescinded from our mental experience. This idea is already present in the “New List,” where Peirce argues that “the impressions cannot be definitely conceived or attended to, to the neglect of an elementary conception which reduces them to unity. On the other hand, when such a conception has once been obtained, […] the explaining conception may frequently be prescinded from the more immediate ones and from the impressions” (W 2:51, 1867). A similar idea is detectable in Peirce’s phaneroscopy or phenomenology, which shows that “[t]he universal categories […] belong to every phenomenon, one being perhaps more prominent in one aspect of that phenomenon than another but all of them belonging to every phenomenon” (EP 2:148, 1903).¹ That is to say, prescission can show that the categories are necessary in order to account for our mental experience, because they are essential in order to make sense of the latter, while, on the other hand, they can be prescinded from experience in general.

Peirce’s use of prescission in phaneroscopy has been accounted for in various ways in the secondary literature. Because phaneroscopy sorts out the fundamental elements in our cognition from an analysis of “the sum of all we have in mind in any way whatever, regardless of its cognitive value” (EP 2:362, 1905), various scholars have compared it to Husserl’s phenomenology, which also investigates what is immediately given in consciousness, disregarding the question of whether representations have any cognitive value (cf. Spiegelberg 1957). In this context, Peirce’s prescission shows resemblances to some procedures used in Husserl’s eidetic variations (cf. Dougherty 1980; Hauser 1989; Stjernfelt 2007: ch. 6, 7, 14). Besides, scholars have defended different views on the role of prescission in phaneroscopy. Some scholars have maintained that prescission, together with hypostatic abstraction, still plays a central role in this science (cf. Houser 1989; Gava 2014, ch. 1). Moreover, insofar as Peirce can be read as using prescission to argue that the categories are necessary conditions for making sense of our mental experience, prescission can be understood, both in the “New List” and in Peirce’s later phaneroscopy, as a modest transcendental strategy of argument (cf. Gava 2011a; Gava 2011b; Gava 2014, ch. 5). In contrast to readings that stress the fundamentality of prescission for phaneroscopy, it has also been argued that Peirce’s phaneroscopy largely abandons the procedures used in the “New List,” including prescission, and leans towards a purely empirical investigation that rejects a priori justification (cf. Short 2007, ch. 3).

References

Notes