Cathy Legg

Robert Brandom’s expressivism argues that not all semantic content may be made fully explicit. This view connects in interesting ways with recent movements in philosophy of mathematics and logic (e.g. Brown, Shin, Giaquinto) to take diagrams seriously - as more than a mere “heuristic aid” to proof, but either proofs themselves, or irreducible components of such. However what exactly is a diagram in logic? Does this constitute a semiotic natural kind? The paper will argue that such a natural kind does exist in Charles Peirce’s conception of iconic signs, but that fully understood, logical diagrams involve a structured array of normative reasoning practices, as well as just a “picture on a page”.

Charles Peirce's diagrammatic logic — the Existential Graphs — is presented as a tool for illuminating how we know necessity, in answer to Benacerraf's famous challenge that most ‘semantics for mathematics’ do not ‘fit an acceptable epistemology’. It is suggested that necessary reasoning is in essence a recognition that a certain structure has the particular structure that it has. This means that, contra Hume and his contemporary heirs, necessity is observable. One just needs to pay attention, not merely to individual things but to how those things are related in larger structures, certain aspects of which relations force certain other aspects to be a certain way

Charles Peirce famously divided all signs into icons, indices and symbols. The past few decades have seen mainstream analytic philosophy broaden its traditional focus on symbols to recognise the so-called essential indexical. Can the moral now be extended to icons? Is there an “essential icon”? And if so, what exactly would be essential about it? It is argued that there is and it consists in logical form. Danielle Macbeth’s radical new “expressivist” interpretation of Frege’s logic and Charles Peirce’s existential graphs are mobilized in support of this claim.

In many diagrams one seems to perceive necessity – one sees not only that something is so, but that it must be so. That conflicts with a certain empiricism largely taken for granted in contemporary philosophy, which believes perception is not capable of such feats. The reason for this belief is often thought well-summarized in Hume's maxim: ‘there are no necessary connections between distinct existences’. It is also thought that even if there were such necessities, perception is too passive or localized a faculty to register them. We defend the perception of necessity against such Humeanism, drawing on examples from mathematics.

Whereas Charles Peirce’s pragmatist account of truth has been much discussed, his theory of perception still offers a rich mine of insights. Peirce presented a ‘two-ply’ view of perception, which combines an entirely precognitive ‘percept’ with a ‘perceptual judgment’ that is located in the space of reasons. Having previously argued that Peirce outdoes Robert Brandom in achieving a hyper-inferentialism (“Making it Explicit and Clear”, APQ, 2008), I now wish to examine his philosophy in the light of inferentialism’s ‘original fount’ – Wilfrid Sellars. Does Peirce’s percept commit him to the Myth of the Given? I argue that it does not, because although the percept is understood as nonepistemic, it is not understood to justify the perceptual judgment. Rather, the perceptual judgement indexes the percept. I explain this original view, then argue that Peirce and Sellars actually have a great deal in common in their rare diachronically mediated yet at the same time direct perceptual realism, and the ‘critical commonsensist’ epistemology to which it gives rise.

Charles S. Peirce’s semiotics uniquely divides signs into: i) symbols, which pick out their objects by arbitrary convention or habit, ii) indices, which pick out their objects by unmediated ‘pointing’, and iii) icons, which pick out their objects by resembling them (as Peirce put it: an icon’s parts are related in the same way that the objects represented by those parts are themselves related). Thus representing structure is one of the icon’s greatest strengths. It is argued that the implications of scaffolding education iconically are profound: for providing learners with a navigable road-map of a subject matter, for enabling them to see further connections of their own in what is taught, and for supporting meaningful active learning. Potential objections that iconic teaching is excessively entertaining and overly susceptible to misleading rhetorical manipulation are addressed.

We discuss the one–many problem as it appears in the Philebus and find that it is not restricted to the usually understood problem about the identity of universals across particulars that instantiate them (the Hylomorphic Dispersal Problem). In fact some of the most interesting aspects of the problem occur purely with respect to the relationship between Forms. We argue that contemporary metaphysicians may draw from the Philebus at least three different one–many relationships between universals themselves: instantiation, subkind and part, and thereby construct three new ‘problems of the one and the many’ (an Eidetic Dispersal Problem, a Genus–Species Problem, and an Eidetic Combination Problem), which are as problematic as the version generally discussed. We then argue that this taxonomy sheds new and interesting light on certain discussions of higher-order universals in recent Australian analytic philosophy.

This paper contrasts the scholastic realisms of David Armstrong and Charles Peirce. It is argued that the so-called 'problem of universals' is not a problem in pure ontology (concerning whether universals exist) as Armstrong construes it. Rather, it pertains to which predicates should be applied where, issues which Armstrong sets aside under the label of 'semantics', and which from a Peircean perspective encompass even fundamentals of scientific methodology. It is argued that Peirce's scholastic realism not only presents a more nuanced ontology (distinguishing existence and reality) but also illuminates why scholastic realism is a position worth fighting for.

Much mainstream analytic epistemology is built around a sceptical treatment of modality which descends from Hume. The roots of this scepticism are argued to lie in Hume’s (nominalist) theory of perception, which is excavated, studied and compared with the very different (realist) theory of perception developed by Peirce. It is argued that Peirce’s theory not only enables a considerably more nuanced and effective epistemology, it also (unlike Hume’s theory) does justice to what happens when we appreciate a proof in mathematics.

Would be fairer to call Peirce’s philosophy of language “extensionalist” or “intensionalist”? The extensionalisms of Carnap and Quine are examined, and Peirce’s view is found to be prima facie similar, except for his commitment to the importance of “hypostatic abstraction”. Rather than dismissing this form of abstraction (famously derided by Molière) as useless scholasticism, Peirce argues that it represents a crucial (though largely unnoticed) step in much working inference. This, it is argued, allows Peirce to transcend the extensionalist-intensionalist dichotomy itself, through his unique triadic analysis of reference and meaning, by transcending the distinction between (as Quine put it) “things” and “attributes”.

Neopragmatism has been accused of having ‘an experience problem’. This paper begins by outlining Hume's understanding of perception according to which ideas are copies of impressions thought to constitute a direct confrontation with reality. This understanding is contrasted with Peirce's theory of perception according to which percepts give rise to perceptual judgments which do not copy but index the percept (just as a weather-cock indicates the direction of the wind). Percept and perceptual judgment thereby mutually inform and correct one another, as the perceiver develops mental habits of interpreting their surroundings, so that, in this theory of perception, as Peirce puts it: “[n]othing at all…is absolutely confrontitional”. Paul Redding has argued that Hegel’s “idealist understanding of logical form” ran deeper than Kant’s in recognising that Mind is essentially embodied and located, and therefore perspectival. Peirce’s understanding arguably dives deeper still in distributing across the space of reasons (and thus Being) not just Mind’s characteristic features of embodiedness and locatedness, but also its infinite corrigibility.

Although certain recent developments in mendacious political manipulation of public discourse are horrifying to the academic mind, I argue that we should not panic. Charles Peirce’s pragmatist epistemology with its teleological arc, long horizon, and rare balance between robust realism and contrite fallibilism offers guidance to weather the storm, and perhaps even see it as inevitable in our intellectual development. This paper explores Peirce’s classic “four methods of fixing belief”, which takes us on an entertaining and still very pertinent tour through tenacity, authority and a priori speculation to the method of science – the only method which is both public and self-correcting. Although in the West we (mostly) proudly self-conceive as living in a ‘scientific age’, I argue that this is premature. Precisely insofar as we treat the misbehavior of governments as a harbinger of doom, we remain trapped in authoritarian modes of thinking which Peirce identified with medievalism, although modernity is increasingly quickening around us in worldwide information-sharing practices that are shaped entirely by mutual help. With this framework in mind, many tactics of recent media are most helpfully seen as belonging not to a post-truth, but a pre-truth stage of human intellectual development. Advice on this is sought from Plato, who of course also faced a world that was ‘pre-academic’.

Enactivism has influentially argued that the traditional intellectualist ‘act-content’ model of intentionality is insufficient both phenomenologically and naturalistically, and minds are built from world-involving bodily habits – thus, knowledge should be regarded as more of a skilled performance than an informational encoding. Radical enactivists have assumed that this insight must entail non-representationalism concerning at least basic minds. But what if it could be shown that representation is itself a form of skilled performance? I sketch the outline of such an account from the perspective of Peirce’s pragmatist semiotics, which theorises signs as habits of associating specific cues with appropriate acts and schemas of ensuing experience. Within this framework, I argue, a naturalistic account of propositional structure can be constructed which transcends the symbolic – and in some instances even the linguistic – sphere, and offers new insights regarding the Information Processing Challenge, and the Hard Problem of Content.

Necessity is a touchstone issue in the thought of Charles Peirce, not least because his pragmatist account of meaning relies upon modal terms. We here offer an overview of Peirce’s highly original and multi-faceted take on the matter. We begin by considering how a self-avowed pragmatist and fallibilist can even talk about necessary truth. We then outline the source of Peirce’s theory of representation in his three categories of Firstness, Secondness and Thirdness, (monadic, dyadic and triadic relations). These have modal purport insofar as the first category corresponds to possibility, the second to mechanical necessity and the third to a kind of semantic or intentional necessity. We then turn to Peirce’s explicit modal epistemology and show how it began as information-relative, with different modalities (e.g. logical, physical, practical) distinguished in terms of respective ‘designated states of information’, and shifted later in his life towards a more robust realism founded in direct perception of ideas in their relations. We then turn to Peirce’s formal logic, focusing on his diagrammatic system of Existential Graphs where he did his most serious logical research. Finally we discuss Peirce’s modal metaphysics and its implications for determinism and realism about universals.

The word “hacker” has an interesting double meaning: one vastly more widespread connotation of technological mischief, even criminality, and an original meaning amongst the tech savvy as a term of highest approbation. Both meanings, however, share the idea that hackers possess a superior ability to manipulate technology according to their will (and, as with God, this superior ability to exercise will is a source of both mystifying admiration and fear). This book mainly concerns itself with the former meaning. To Thomas this simultaneously mystified and vilified, elusive set of individuals exemplifies “the performance of technology” xx), showing the way in which “the cultural, social and political history of the computer...is fraught with complexity and contradictions” ix). In fact, he claims that hacking is more a cultural than technological phenomenon, citing Heidegger’s, “[t]he essence of technology is not anything technological” (56).

This paper offers an expressivist account of logical form, arguing that in order to fully understand it one must examine what valid arguments make us do (or: what Achilles does and the Tortoise doesn’t, in Carroll’s famed fable). It introduces Charles Peirce’s distinction between symbols, indices and icons as three different kinds of signification whereby the sign picks out its object by learned convention, by unmediated indication, and by resemblance respectively. It is then argued that logical form is represented by the third, iconic, kind of sign. It is noted that icons uniquely enjoy partial identity between sign and object, and argued that this holds the key to Carroll’s puzzle. Finally, from this examination of sign-types metaphysical morals are drawn: that the traditional foes metaphysical realism and conventionalism constitute a false dichotomy, and that reality contains intriguingly inference-binding structures.

Wikipedia is a goldmine of information; not just for its many readers, but also for the growing community of researchers who recognize it as a resource of exceptional scale and utility. It represents a vast investment of manual effort and judgment: a huge, constantly evolving tapestry of concepts and relations that is being applied to a host of tasks. This article provides a comprehensive description of this work. It focuses on research that extracts and makes use of the concepts, relations, facts and descriptions found in Wikipedia, and organizes the work into four broad categories: applying Wikipedia to natural language processing; using it to facilitate information retrieval and information extraction; and as a resource for ontology building. The article addresses how Wikipedia is being used as is, how it is being improved and adapted, and how it is being combined with other structures to create entirely new resources. We identify the research groups and individuals involved, and how their work has developed in the last few years. We provide a comprehensive list of the open-source software they have produced.

Mainstream philosophy has seen a recent flowering in discussions of intellectualism which revisits Gilbert Ryle’s famous distinction between ‘knowing how’ and ‘knowing that’, and challenges his argument that the former cannot be reduced to the latter. These debates so far appear not to have engaged with pragmatist philosophy in any substantial way, which is curious as the relation between theory and practice is one of pragmatism’s main themes. Accordingly, this paper examines the contemporary debate in the light of Charles Peirce’s habit-based epistemology. We argue both that knowing-that can be understood as a particularly sophisticated form of knowing-how, and that all bodily competencies—if sufficiently deliberately developed—can be analysed as instantiating propositional structure broadly conceived. In this way, intellectualism and anti-intellectualism are seen to be not opposed, and both true, although Peirce’s original naturalistic account of propositional structure does lead him to reject what we shall call ‘linguistic intellectualism’.

Much discussion of meaning by philosophers over the last 300 years has been predicated on a Cartesian first-person authority (i.e. “infallibilism”) with respect to what one’s terms mean. However this has problems making sense of the way the meanings of scientific terms develop, an increase in scientific knowledge over and above scientists’ ability to quantify over new entities. Although a recent conspicuous embrace of rigid designation has broken up traditional meaning-infallibilism to some extent, this new dimension to the meaning of terms such as “water” is yet to receive a principled epistemological undergirding (beyond the deliverances of “intuition” with respect to certain somewhat unusual possible worlds). Charles Peirce’s distinctive, naturalistic philosophy of language is mined to provide a more thoroughly fallibilist, and thus more realist, approach to meaning, with the requisite epistemology. Both his pragmatism and his triadic account of representation, it is argued, produce an original approach to meaning, analysing it in processual rather than objectual terms, and opening a distinction between “meaning for us”, the meaning a term has at any given time for any given community and “meaning simpliciter”. the way use of a given term develops over time (often due to a posteriori input from the world which is unable to be anticipated in advance). This account provocatively undermines a certain distinction between “semantics” and “ontology” which is often taken for granted in discussions of realism.

Philosophical discussion of truthmaking has flourished in recent times, but what exactly does it mean to ‘make’ a truth-bearer true? I argue that ‘making’ is a concept with modal force, and this renders it a problematic deployment for truthmaker theorists with nominalist sympathies, which characterises most current theories. I sketch the outlines of what I argue is a more genuinely realist truthmaker theory, which is capable of answering the explanatory question: In virtue of what does each particular truthmaker make its particular truthbearer(s) true? I do this by drawing on recent work by Frederik Stjernfelt on Charles Peirce’s account of the proposition as having a ‘particular double structure’, according to which a proposition not only depicts certain characters of an object, it also depicts itself claiming those characters to pertain to the object. This double structure, I shall argue, also resolves important issues in analytic philosophers’ truthmaker theory, including the proper distinction between reference and truthmaking, and a dilemma concerning an infinite regress of truthmaking.

Peirce wrote that Hume’s argument against miracles (which is generally liked by twentieth century philosophers for its antireligious conclusion) "completely misunderstood the true nature of" ’abduction’. This paper argues that if Hume’s argumentative strategy were seriously used in all situations (not just those in which we seek to "banish superstition"), it would deliver a choking epistemological conservatism. It suggests that some morals for contemporary naturalistic philosophy may be drawn from Peirce’s argument against Hume.

It seems possible to know that a mathematical claim is necessarily true by inspecting a diagrammatic proof. Yet how does this work, given that human perception seems to just (as Hume assumed) ‘show us particular objects in front of us’? I draw on Peirce’s account of perception to answer this question. Peirce considered mathematics as experimental a science as physics. Drawing on an example, I highlight the existence of a primitive constraint or blocking function in our thinking which we might call ‘the hardness of the mathematical must’.