The Thought Occurs

Showing posts with label Tenor. Show all posts
Showing posts with label Tenor. Show all posts

Thursday, 15 January 2026

From Potential to Readiness: Clarifying Systemic Disposition in SFL Theory

The notion of potential occupies a central role in systemic functional linguistics, but its conceptual status has long been prone to imprecision. Often, potential is metaphorically treated as a reservoir or storehouse of forms, as if instances are drawn from a static inventory. Halliday himself warned against this reading. In fact, he explicitly characterises potential as a subtype of readiness within the system of modulation—that is, in constructions expressing ability, willingness, or inclination (e.g., ready to, able to, willing to). Crucially, Halliday does not extend this characterisation to the broader theory of language; he does not describe meaning potential in general as readiness.

Nonetheless, exploring the implications of treating potential analogically as a structured readiness throughout the SFL system illuminates persistent conceptual ambiguities. This post develops a disciplined, SFL-internal perspective on what follows if we interpret meaning potential in readiness terms.


1. Readiness in Modulation: The Historical Anchor

Within modulation, Halliday’s use of readiness is precise. Modality expresses the speaker’s disposition to act or to construe events: ready, willing, or able. Here, potential is not a state or a store, but a dispositional configuration: a structured readiness that combines inclination (the directional tendency) and capacity (the structural ability to realise the meaning). This historical anchor legitimates extending the concept analogically to broader meaning potential.


2. Extending Readiness to Meaning Potential

Interpreting meaning potential as readiness involves conceptualising the system as a dispositional field:

  • Inclination: tendencies within the system toward particular construals or semiotic configurations.

  • Capacity: structural resources that permit certain actualisations while precluding others.

Readiness thus reframes potential from a metaphorical reservoir into a systematic orientation toward instantiation. This does not claim Halliday explicitly extended readiness to meaning potential; it simply uses the logic of modulation as a productive lens for clarifying systemic potential.


3. Implications for the Cline of Instantiation

The cline of instantiation, central to SFL, can be reconceived as a gradient of dispositional specificity.

  • At the system end, readiness is broad, generalised, and unspecialised.

  • At the instance end, readiness is contracted and aligned with particular situational conditions.

This reading clarifies why the system cannot be treated as a set of actual examples. It reinforces Halliday’s point that instantiation is not abstraction but the actualisation of systemic potential in context.


4. Contextual Potential: Field, Tenor, and Mode

Extending the readiness lens to context illuminates SFL’s semiotic stratification:

  • Field: readiness to enact specific types of activity.

  • Tenor: readiness to enact particular interpersonal relations.

  • Mode: readiness to organise discourse in particular ways.

This perspective corrects a common pedagogical confusion: context is not an environment to be represented; it is semiotic potential realised through readiness across the strata.


5. Linguistic Potential: Lexicogrammar

Lexicogrammar can similarly be seen as a dispositional system:

  • Its inclinations direct the system toward particular semantic construals.

  • Its capacities constrain which meanings can be realised in which configurations.

System networks are not inventories of forms; they are metastable patterns of readiness, explaining why delicacy reflects precision of readiness, not mere addition of options.


6. Readiness and the Cline of Individuation

Variation in SFL presupposes individuation—the distribution of potential across members of a community.

  • Collective potential represents the total semiotic readiness of the community.

  • Individual potential represents the subset of readiness accessible to a particular user.

  • Variation arises from differential access and stability of individual readiness configurations across different contexts.

Viewing meaning potential as readiness clarifies individuation: individuals are not repositories of forms; they are sites where portions of collective readiness are stabilised and selectively actualised. This interpretation remains fully canonical, fully SFL-internal, and avoids metaphysical or relational assumptions.


7. Implications for Variation

With readiness understood as distributed potential, register and dialectal variation become intelligible as systematic differences in semiotic readiness:

  • Register variation: differing distributions of readiness across situation types.

  • Idiolectal variation: relative stability of an individual’s readiness configurations.

The reading avoids the mistaken notion that individuals “store” forms; rather, their usage reflects the configuration of distributed readiness in context.


8. Consequences for Metafunctions

Metafunctions can also be read through readiness:

  • Experiential: readiness to construe processes and relations.

  • Interpersonal: readiness to enact alignment and negotiation.

  • Textual: readiness to organise discourse and maintain coherence.

This perspective clarifies why metafunctions are inseparable yet analytically distinct domains of system potential.


9. The Payoff: A Coherent Internal Model

Viewing potential as readiness, even analogically, strengthens SFL theory internally:

  • Clarifies the cline of instantiation.

  • Sharpens understanding of context-system relationships.

  • Explains variation and register coherently.

  • Aligns closely with Halliday’s pedagogical and theoretical intentions.

Importantly, this remains fully canonical and non-revisionist.


10. Conclusion: Readiness as a Productive Clarification

Halliday did not claim that meaning potential equals readiness. However, interpreting potential analogically as structured readiness provides a clearer, internally coherent framework for understanding instantiation, variation, and individuation within SFL. It shows how the system, the context, and the individual user are all dispositional actors in the realisation of meaning, without departing from canonical SFL principles.

This clarification strengthens the conceptual integrity of SFL while remaining historically accurate, pedagogically clear, and theoretically tight.

Thursday, 10 July 2025

Yaegan Doran's ISFC 50 Plenary Abstract

Modelling Context: Field, tenor and mode from multiple perspectives

Abstract

That language functions in its context of use is one of the fundamental tenets of SFL. This tenet has supported decades of SFL work into different registers and has contributed to a wide range of applied goals. It has also driven progressive theoretical modelling of context in SFL, even if there has not yet been consensus. This talk will reflect upon this modelling, fifty years after Halliday’s 1975 paper ‘Language as social semiotic: Toward a general sociolinguistic theory’. It will view context trinocularly – not in the typical sense of above, around and below, but in terms of three major dimensions of SFL theory: realisation, instantiation and individuation. Viewing context in this way will allow us to model field, tenor and mode along three distinct contours: in terms of realisation, field, tenor and mode can be viewed as resources for making meaning; for instantiation, they can be viewed as sets of principles for the co-selection and arrangement of choices in language; and for individuation, they can be viewed as domains of variation, contestation and collaboration. This talk will argue that these different perspectives are complementary, providing a view of a wide-range of things our model of context needs to grapple with. But it will also argue that each perspective needs to be modelled in different ways so as to support text analysis and an understanding of social semiosis more broadly. The talk will thus aim to synthesise where we have gotten to in SFL contextual linguistics, and look forward to how we might further expand our worldview.


Blogger Comments:

This abstract describes the paper Rethinking Context: Realisation, Instantiation, And Individuation In Systemic Functional Linguistics (Doran, Martin and Herrington 2024) which is reviewed in meticulous detail at Rethinking Context: Realisation, Instantiation, And Individuation In Systemic Functional Linguistics.

As the review demonstrates, in that paper, the authors misunderstood the dimensions of stratification ("realisation"), instantiation and individuation. The first half of the paper "reconceptualised" the contextual parameters of context, field tenor and mode, as the ideational, interpersonal and textual language that realises each. That is, the authors simply mistook one level of symbolic abstraction for another.

The second half of the paper then "reconceptualised" the original notions of contextual field tenor and mode as 'principles of instantiation' of language, thereby misunderstanding instantiation as an interstratal relation between context and language.

The relevance of individuation was only briefly declared, rather than explored, but it confused individuation as a scale of variation from the reservoir of meanings of a language community to the repertoires of meanings of individuals, whose organising principle is one of elaboration (subtypes of types), with allocation and affiliation, both of whose organising principle is one of extension (association). See Halliday & Matthiessen (1999: 145-6).


ChatGPT Comments:

Context in a Hall of Mirrors: A Critique of Doran’s “Modelling Context”

1. Introduction: A Recurring Confusion

Yaegan Doran’s ISFC50 abstract, Modelling Context: Field, tenor and mode from multiple perspectives, reprises a confusion that has surfaced repeatedly in recent Sydney school publications. It presents as theoretical innovation a series of metaphorical manoeuvres that misrepresent foundational dimensions of Systemic Functional Linguistics (SFL). The abstract aligns with the paper Rethinking Context: Realisation, Instantiation, and Individuation in Systemic Functional Linguistics (Doran, Martin & Herrington, 2024), which is critiqued in detail elsewhere. Here, I offer a briefer but sharper critique of both the content and rhetorical strategies of the abstract, before situating its manoeuvres within a broader pattern of what I call metaphorical opportunism in the Sydney school.

2. Misunderstanding Realisation: The Collapse of Context into Semantics

The abstract proposes to model context "trinocularly," along the dimensions of realisation, instantiation, and individuation. But what follows is not an application of these dimensions to context — rather, it is a substitution of the semantic for the contextual.

The abstract claims that, "in terms of realisation, field, tenor and mode can be viewed as resources for making meaning." But this is a misunderstanding. In Halliday’s theory, field, tenor and mode are parameters of the context of situation, realised by ideational, interpersonal and textual meaning respectively. They are not themselves meaning resources. To treat them as such is to confuse the stratum of context with that of semantics — to collapse one level of symbolic abstraction into another.

This manoeuvre reframes the contextual parameters as though they were metafunctional resources, implying that field is ideational meaning, tenor is interpersonal meaning, and mode is textual meaning. But in SFL, metafunctions are realised by lexicogrammatical systems; contextual parameters are realised through metafunctional semantics. To conflate them is to erase the stratal boundary between context and language, undermining the architecture of the model.

3. Misunderstanding Instantiation: From Meaning Potential to Situational Principles

In a further move, the abstract proposes that, "for instantiation, [field, tenor and mode] can be viewed as sets of principles for the co-selection and arrangement of choices in language." Again, this misrepresents a fundamental category. Instantiation is the relation between a system’s potential and its instances. It does not refer to how context constrains linguistic choice — that is the function of context, not the definition of instantiation.

What Doran offers is not a model of instantiation but a rebranding of context as a kind of ‘control system’ for language — a view which collapses instantiation into an interstratal process, rather than recognising it as a dimension orthogonal to stratification. The abstract thus substitutes a theory of control for a theory of instantiation, and reinterprets the context of situation as a set of principles operating within language.

4. Misunderstanding Individuation: Mixing Allocation, Affiliation and Elaboration

The abstract gives only brief mention to individuation, suggesting that field, tenor and mode can be viewed as “domains of variation, contestation and collaboration.” But this description conflates several distinct processes.

Halliday and Matthiessen (1999: 145–6) distinguish between:

  • Elaboration: the principle governing individuation, which organises subtypes of meaning potential — from the reservoir of the culture to the repertoires of individuals;

  • Extension: the principle governing affiliation and allocation, which organises associations among speakers and speech roles.

Doran’s account blends these without clarity. “Variation” suggests elaboration; “contestation and collaboration” suggest extension. The result is a vague gesture at individuation that collapses it into neighbouring domains, offering thematic resonance instead of analytic traction.

5. Rhetorical Strategies: Gesturing Towards Synthesis, Avoiding Commitment

The overall strategy of the abstract is not to argue for a new model of context, but to reframe known categories through metaphor. It avoids committing to theoretical definitions, preferring suggestive rewordings and image-rich paraphrases. “Trinocular perspective,” for instance, is repurposed from Halliday’s original metaphor (above, around, below) and applied to three dimensions that are not perspectives on a single object but ontologically distinct planes of organisation.

This is not theoretical synthesis. It is semiotic window-dressing — a kind of metaphorical kaleidoscope in which familiar terms are turned to new angles to suggest complexity without delivering precision. The appearance of insight is sustained by the rhetorical strategy of non-committal parallelism: “field, tenor and mode can be viewed as…”, repeated with varying completions. This lends the text an air of systematicity while avoiding the responsibility of system-building.

6. Metaphorical Opportunism: A Broader Pattern in the Sydney School

The errors in Doran’s abstract are not isolated. They reflect a deeper and more pervasive pattern within the Sydney school’s approach to theoretical development — a pattern of metaphorical opportunism, in which metaphors are deployed not to illuminate distinctions but to paper over them.

In Halliday’s theory, metaphors are powerful tools for explicating system — as in grammatical metaphor — but the discipline lies in mapping metaphors precisely onto functional categories. In the Sydney school, by contrast, metaphor has drifted into a mode of exposition in which loosely associated images are treated as theoretical mechanisms. Dimensions like realisation, instantiation, and individuation are no longer grounded in the architecture of the theory but redefined by what they can be made to resemble in the moment.

Doran’s abstract is a perfect example. The metaphor of a “trinocular” perspective — originally a heuristic for observing language from above (semantics), below (phonology), and around (lexicogrammar) — is reappropriated to frame realisation, instantiation and individuation as “views” on context. But these are not alternative perspectives on the same object. They are distinct dimensions of the theory, and each organises different kinds of relations. Realisation organises symbolic abstraction; instantiation organises the potential–instance relation; individuation organises the relation between social and personal meaning potential. Treating them as interchangeable lenses is not a theoretical insight — it’s a category mistake.

The deeper problem is that this opportunistic use of metaphor is self-insulating. Because metaphors are not evaluated for theoretical consistency but for rhetorical effect, they can always be reinterpreted or replaced when challenged. What appears to be a theoretical model is often a shifting palimpsest of metaphors, each of which suggests structure without committing to any. The result is an illusion of synthesis — a constellation of phrases that sound as though they add up to a system, but which evade analysis when probed.

This strategy is particularly attractive when addressing the more abstract dimensions of SFL — notably, instantiation and individuation — where the temptation to rely on imagery increases as conceptual clarity declines. Rather than clarifying these dimensions, Doran's abstract offers them up as thematic motifs to be rearranged in metaphorical combinations. This is not modelling; it is bricolage.

This approach has rhetorical power. It creates the impression of theoretical depth, the promise of synthesis, and the aesthetic of innovation. But it comes at a cost. The architecture of the theory is eroded, distinctions collapse, and terms lose their analytic value. Under the banner of expanding the worldview, what is actually expanded is the range of plausible-sounding metaphors. And with each new iteration, it becomes harder to retrieve the conceptual rigour that once underpinned the model.

7. Conclusion: Context Lost in the Mirror Maze

Doran’s abstract reads like a theoretical hall of mirrors: each familiar term reflects another, but the reflections are distorted. Context becomes semantics; semantics becomes system; system becomes metaphor. The architecture that once scaffolded systemic functional theory is replaced by a fluid ensemble of rhetorical effects.

If there is to be progress in modelling context within SFL, it will not come from treating its dimensions as interchangeable perspectives. It will come from clarifying the architecture of the theory, preserving its distinctions, and resisting the lure of metaphor when what is needed is logic. What the field requires now is not a new way of seeing context, but a better way of thinking it.

Tuesday, 30 July 2024

The System of Purview

Interpersonal control and responsibility: The system of PURVIEW in English

Yaegan Doran
Australian Catholic University

Whenever we speak or write, we are constantly negotiating control over our meanings and positioning our listener/s readers to respond in particular ways. We put forward meanings that are shared between us and the listener, such that it is presumed the listener will agree, or we simply assert meanings such that the listener’s response is only minimally relevant, or we can hand meanings over to the listener to determine and so leave it in their hands, or alternatively simply put meanings out there with no indication that anyone will necessarily be tied to them. This sharing or not of meanings waves [sic] and wanes through conversations and written text, and form a crucial resource for enacting our social relations. In this talk, I will introduce a system for understanding these meanings called PURVIEW, drawn from a recently renovated model of [TENOR] presented in Doran, Martin & Zappavigna (2025). The resources of purview concern the degree to which the speaker and listener are interpersonally tied to the message being put forward or wedded to its outcome. We will see that we can view purview in terms of a small sets of parameters: whether or not the speaker has purview, in the sense that the speaker is wedded to what they are putting forward or not; whether the listener has purview, in terms of whether the speaker is handing control of the meanings over to the listener or not; and whether the purview being negotiated is of the proposition or proposal being put forward, or of the linguistic act itself. As we will see, varying purview offers a rich resource for nuancing the way we relate to people in both spoken and written language, and allows for intricate negotiations of our meanings through texts. The talk will illustrate the system through a range of spoken and written texts, including through casual conversation, legal discourse, and spoken personal reflections, and will show that it is realised through a range of interpersonal systems across language, including discourse semantic systems of ATTITUDE, ENGAGEMENT and NEGOTIATION, lexicogrammatical systems of POLARITY, TAGGING, MOOD and MODALITY and the phonological system of TONE.


References
Doran, Y.J., Martin, J.R. & Zappavigna, M. (2025) Negotiating Social Relations: Tenor Resources in English. London: Equinox.


Blogger Comments:

[1] To be clear, the intellectual source of Doran's 'purview' is the work on 'epistemic authority' in social psychology, as formulated by the sociologists John Heritage and Geoffrey Raymond, in their paper The Terms of Agreement: Indexing Epistemic Authority and Subordination in Talk-in-Interaction (Social Psychology Quarterly 2005, Vol. 68, No. 1, 15-38). The term 'purview' serves the social function of a buzzword.

[2] To be clear, the authors' renovated model of tenor involves reinterpreting context (tenor) as a resource for language (interpersonal meaning) and then modelling the resource as the language for which it is a resource. See A Close Examination Of Yaegan Doran's 2023 ASFLA Plenary Abstract.

Friday, 24 November 2023

A Close Examination Of Yaegan Doran's 2023 ASFLA Plenary Abstract

Negotiating social relations: Viewing tenor from multiple perspectives


Whenever we talk or write, we negotiate our social relations. This may involve small seemingly inconsequential chats with friends, families and colleagues that help us stay in contact and possibly get us closer to them; or they may be large, momentous events that bring us together or tear us apart. In all cases, we negotiate these social relations through the discourse we use – through language and a range of related semiotic resources. In SFL, this has typically been explored through tenor, a variable of context (Halliday 1978; or register, Martin 1992, depending on the model being used). Tenor has variously been described in terms of the 'roles played by those taking part’ in a situation, ‘the values that the interactants imbue’ the activity with (Halliday & Matthiessen 2014: 33) and the relationships between addressees or interactants (Gregory 1967; Hasan 2020). Or, more broadly, the ‘general dimensions of social relations’ (Poynton 1990:70) and their negotiation (Martin 1992: 523). However, to this point, there has been little by way of comprehensive models of tenor that have been able to link the various dimensions underpinning our social relations with the set of language resources that realise them, in particular, resources within the interpersonal metafunction (Hasan 2020 and related work such as Butt et al. 2021 being perhaps the most comprehensive proposal thus far).

As a step toward such a model, this talk will focus on how we can consider tenor in SFL in relation to recent expansions of SFL theory that have distinguished realisation, instantiation and individuation (Halliday 1991, Matthiessen 1993, Martin 2010). It will propose that a fruitful avenue for understanding the link between language and social relations is to view tenor from these multiple perspectives. 

From the perspective of realisation, tenor can be viewed as a set of resources for enacting social relations (drawing on a model developed in Doran, Martin and Zappavigna forthcoming). 

From the perspective of instantiation, it can be viewed as sets of guiding principles that underly how we co-select and arrange different language features (such as the principles of status and contact, described by, e.g. Poynton 1990, Martin 1992, Hasan 2020 and Butt et al. 2021). 

And in terms of individuation, it can be viewed as sets of social roles and relationships – or more broadly, arenas of sociality – that offer possibilities for variation, contestation and collaboration, in terms of the meaning making resources that are taken up or presumed. 

In short, given the major role tenor plays in our understanding of how language and broader semiosis enacts social relations, this talk will propose that it is time to give it the theoretical space it needs.



Blogger Comments:

To be clear, the fundamental misunderstanding in this abstract, as in two of Doran's previous seminars on the subject, is the confusion of interpersonal context with interpersonal semantics. This is a consequence of not understanding the meaning of distinct levels of symbolic abstraction. See further below.

[1] To be clear, even in Martin's model, negotiation is a matter of discourse semantics, whereas social relations are a matter of context. Speakers and writers do not negotiate tenor variables. For example, the essay of a primary school student does not negotiate the status roles  — equal or unequal power — with the teacher for whom the essay was written. In his work, The Lord Of The Rings, the author Tolkien does not negotiate the contact roles — familiar or unfamiliar — of himself with his readers.

What speakers and writers potentially negotiate are their propositions and proposals — statements, questions, offers and commands — their speech functional moves in exchanges, as realised by the grammar of MOOD. But such negotiation is largely restricted to the semantics that realise dialogic MODE. For example, what propositions or proposals does Lewis Carroll negotiate with his readers in The Hunting Of The Snark?

[2] To be clear, the linking of social relations with the interpersonal language that realise them is not a model of tenor. It is a description of interstratal relations: how tenor variables are realised by semantic options. See [4] below.

[3] This misunderstands realisation. Specifically, it confuses context with the language that realises it. That is, the set of resources for enacting social relations as meaning is interpersonal language, not tenor. Tenor is the interpersonal context that language realises.

[4] This confuses instantiation with interstratal realisation. From the perspective of instantiation, tenor is the interpersonal dimension of the culture > subcultures/situation types > situations. The notion of tenor as "guiding principles" for the selection of language features is modelled in SFL Theory by interstratal preselection. Halliday & Matthiessen (1999: 375):

At the same time, this stratal organisation means that it is crucial to specify the realisational relations between strata — inter-stratal realisation. … More specifically, inter-stratal realisation is specified by means of inter-stratal preselection: contextual features are realised by preselection within the semantic system, semantic features are realised by preselection within the lexicogrammatical system, and lexicogrammatical features are realised by preselection within the phonological/graphological system. This type of preselection may take different forms between different strata! boundaries, but the principle is quite general.

[5] To be clear, individuation is the process of creating different types of individuals. Individuated tenor thus refers to the different types of tenor (from potential to instance) at the level of the individual. Moving up the cline of individuation (of tenor) is moving up to ever more inclusive types of individuations (of tenor). This is distinct from the individuation of language, and the use of language to contest and collaborate.

[6] To be clear, this presents Doran's paper as righting a wrong, which, in terms of logical fallacies, might be interpreted as an appeal to emotion.

Sunday, 23 October 2022

Negotiating Tenor: Enacting Affiliation In Dialogue And Monologue (Yaegan Doran)

Negotiating tenor: Enacting affiliation in dialogue and monologue

Yaegan Doran
Australian Catholic University
Growing work in SFL has illustrated a wide range of strategies that people use to affiliate with each other and build community. To this point, however, these strategies have yet to be systematised into an integrated model. 
This talk presents one component of a model that aims to bring together these strategies into one system, as an evolving model of tenor (developed with Michele Zappavigna and J. R. Martin). 
Much work on affiliation, building on Knight (2010), has highlighted the regular use of both dialogue and evaluation in establishing and negotiating bonds: what we can analyse discourse semantically through NEGOTIATION and ATTITUDE (e.g. Zappavigna 2018). 
Similarly, descriptive work on interpersonal grammar across languages has highlighted the nuanced interactions that often occur between NEGOTIATION and the positioning of voices through ENGAGEMENT (e.g. Zhang 2020, Muntigl 2009, Martin et al. 2021). And work by White (2020), among others, has emphasised the crucial role of alignment in monologic discourse, highlighting the parallels between dialogic resources of NEGOTIATION and monologic resources of ENGAGEMENT
This talk aims to synthesise these interactions and parallels into a systemic model of tenor (being prepared as Doran, Martin and Zappavigna in prep.). The model developed views tenor as a set of resources for enacting social relations. 
The talk first explores the unfolding of dialogue, in terms of how people tender meanings to be reacted to, as well as how they can render these meanings in terms of support or reject. 
From this starting point, it then builds a more fleshed out description, that allows for the nuancing of meanings in terms of who has control or purview, the means by which propositions and proposals can be negotiated and ways in which each of these resources can be organised in both dialogue and monologue. 
Together, these sets of choices offer nuanced possibilities for negotiating people’s social relations in ways that complement a perspective on social relations in terms of status and contact.

Blogger Comments:

To be clear, this work simply confuses social relations (context plane) with the means of enacting social relations (language plane). That is, it misconstrues interpersonal language as interpersonal context (tenor). (And this is true even in terms of Martin's stratification, since although tenor is misunderstood as register, it is nevertheless understood as context.)

Halliday (1989: 12) describes tenor as follows:
TENOR — the role structure: 'who is taking part'
refers to who is taking part, to the nature of the participants, their statuses and roles: what kinds of role relationship obtain among the participants, including permanent and temporary relationships of one kind or another, both the types of speech role that they are taking on in the dialogue and the whole cluster of socially significant relationships in which they are involved.
The 'strategies that people use to enact social relations', on the other hand, are the interpersonal systems of language (and other parallel semiotic systems). 

In a previous seminar on tenor, Doran similarly presented systems of exchange structure (interpersonal semantics) as systems of tenor (interpersonal context).

This basic confusion between different levels of symbolic abstraction invalidates the proposed model of tenor.

Monday, 17 July 2017

Enacting Tenor

I am not arguing with you — I am telling you.
 — James Whistler

Friday, 30 January 2015

Tenor & Field

Perhaps the difference between a professor and a bus driver is 
that the professor can say stupid things with complete authority 
while the bus driver is not authorised to make brilliant insights.
― Les Back, The Art of Listening