ISSA Proceedings 2014 – Ethos And Authority Argumentation: Four Kinds Of Authority In Medical Consultation

Abstract: The authority that the patient ascribes to the doctor in medical consultation influences the way in which this consultation proceeds. In an argumentative discussion, this ascribed authority can affect the acceptability of the doctor’s argumentation. To analyse a doctor’s authority argumentation in medical consultation, I shall make a fourfold analytical distinction between ways in which authority can influence the outcome of an argumentative discussion.

Keywords: Authority argumentation, doctor-patient consultation, ethos, pragma-dialectics

1. Introduction
In medical consultation, a patient typically requests a medical consultation to have his health problem diagnosed by the doctor and, based on this diagnosis, to obtain medical advice. By his request, the patient indicates that he does not know what is the matter with him, how serious his health problem is, or how to best handle this problem, but trusts that the doctor knows this – or can refer him to a specialist based on a medical examination. The patient, thus, ascribes authority on his health problem to the doctor.

The authority ascribed to the doctor influences the way in which the consultation proceeds. The patient will expect the doctor to guide, and thereby structure, the communicative exchange in order to come to an appropriate advice (or parts thereof, such as the diagnosis and prognosis). Moreover, in case of an argumentative discussion in medical consultation, the authority that the patient ascribes to the doctor can influence the acceptability of his argumentation to the patient. First of all, the simple fact that the patient regards the doctor as an authority on his health problem might be enough for the patient to accept the doctor’s argumentation about this problem. Secondly, the doctor can attempt to convince the patient of a medical advice by emphasising his expertise in the course of the consultation or by presenting this expertise as an argument in support of the medical advice.

To analyse a doctor’s use of authority in argumentative discourse, I shall, in this contribution, distinguish analytically between four ways in which authority can influence the outcome of a discussion. More specifically, I shall discuss: existing ethos (section 2), acquired ethos (section 3), the argument from authority (section 4) and the argument by authority (section 5).

2. Existing ethos
A patient requests a consultation by a doctor because of the doctor’s medical qualifications. These qualifications for practicing medicine are highly regulated. Council Directive 93/16/EEC (Art. 23), for instance, lays down which standards that doctors have to meet to practise medicine within the European Union: amongst others, doctors have to possess “adequate knowledge of clinical disciplines and practices, providing him with a coherent picture of mental and physical diseases, of medicine from the points of view of prophylaxis [treatment intended to prevent disease], diagnosis and therapy and of human reproduction”.

A patient who requests a consultation is not sure what his health problem is about, how serious it is, or what to do about it, whereas the doctor’s qualifications indicate that he possesses the medical knowledge and expertise to provide adequate diagnosis and advice. In the consultation, there is consequently an asymmetry between the doctor and patient: the doctor acts as the expert and the patient as a layman (see, on the intrinsic nature of this asymmetry, Pilnick and Dingwall, 2011).

The excerpt of the consultation in Case 1a illustrates this asymmetry in medical expertise between the doctor and the patient.[i] In this consultation, the patient asks for the diagnosis of a health problem that he experienced in the past. He makes clear that he expects the doctor to possess the expertise that is necessary to provide such a diagnosis.

Case 1a
Excerpt of an argumentative discussion between a doctor (D) and a patient (P) about the patient’s possible inguinal rupture

1. D: It could be the case that it had been a fracture.
2. P: Yes.
3. D: But that is also not sure.
4. P: No, no, but I thought that doctors could feel that just like that.

The statement “but I thought that doctors could feel that just like that” (turn 4) shows that the patient requests the consultation because of his expectations about the doctor’s medical expertise. The doctor does not completely live up to these expectation: he cannot determine for sure whether the patient suffered from an inguinal rupture in the past (turns 1 and 3). Nonetheless, the doctor possesses the knowledge and expertise to judge whether and with how much certainty he can diagnose the possible fracture. Contrastingly, the patient requested the consultation because he lacks the medical expertise to diagnose the problem himself.

The asymmetry in medical knowledge and expertise between the doctor and the patient can influence the acceptability of the doctor’s argumentation. A patient might find argumentation on medical issues presented by a doctor more acceptable than the same argumentation presented by someone who is not a doctor. The authority of the discussion party on the issue under discussion then renders his argumentation more acceptable (see also Walton, 1996, p. 64).

The potential effect that a speaker’s authority has on the acceptability of his argumentation has already been studied in classical rhetoric. The rhetorical term ethos is used to denote the persuasiveness of a person’s character. This term stems from Aristotle (The art of rhetoric, I2-1356a), who distinguishes it from pathos (the persuasiveness of emotions) and logos (the persuasiveness of examples or enthymemes). Traditionally, a distinction is made between ethos derived from a person’s expertise (“what one knows”) and ethos derived from his status (“what one is”) (Tindale, 2011, p. 343). From a rhetorical perspective, the doctor’s medical expertise contributes to his ethos in the first sense: ethos derived from what the doctor knows.

The doctor can also be expected to possess ethos in the second sense: ethos derived from his status. Even though the doctor’s role in medical consultation has changed since the 1960s from a paternalistic one to one in which he acts as the patient’s guide (Helmes, Bowen & Bengel, 2002, p. 150), doctors possess professional status due to their advisory role on issues of medicine.

Because of their professional status, doctors can be expected to provide medical advice that is in the patient’s best interest. In case 2, the doctor makes this explicit after an apparently hypochondriac patient expresses doubt about the way in which doctors practise medicine.

Case 2
Excerpt of an argumentative discussion between a doctor (D) and a patient (P) who complains about doctors

1. D: You know, we truly try our utmost to do it as well as possible for you […] And you do have to trust on that.
2. P: Yes.
3. D: Because that really is the case.

In this excerpt, the doctor makes explicit that she and her colleagues do everything in their power to adequately diagnose and advise the patient (turn 1). This is a rather exceptional situation: characteristically, doctors do not make their good intentions explicit in the consultation; these intentions are simply presupposed. Codes of conduct, such as the Hippocratic Oath and the Declaration of Geneva, provide for them. The doctor’s professional status, thus, generally provides him with existing ethos. Nevertheless, in case 2, the patient complaints about doctors, which leads the doctor to assure that there is no need for distrusting them (turn 1).[ii]

3. Acquired ethos
For the analysis of a discussion party’s ethos, it is necessary to distinguish between the ethos that the party possesses at the start of the argumentative discourse and the ethos that he acquires during this discourse. A discussion party can acquire ethos during the discourse by demonstrating his authority, expertise, knowledge, professionalism, status or trustworthiness (“I was just advising a colleague on how he could better consult his client when it occurred to me that …”). The persuasiveness of the party’s ethos then depends on the manner in which he builds ethos in the discussion, not simply on the ethos that is already in place.

As these ways in which a discussion party can come to possess ethos affect the discourse differently, I shall make the analytical distinction between ‘acquired ethos’ (built in the discourse) and ‘existing ethos’ (already in place at the start of the discourse). This distinction is similar to Aristotle’s ideas on persuasive means in oratory. He distinguishes between artistic proofs (entechnoi pisteis; sometimes also translated as ‘intrinsic proofs’ or ‘technical proofs’) and inartistic ones (atechnoi pisteis; also ‘extrinsic proofs’ or ‘non-technical proofs’). The artistic proofs are the verbal persuasive means that the speaker uses within the discourse, while the inartistic proofs are the persuasive means that exist independently of the speaker. So, acquired ethos corresponds with Aristotle’s concept of artistic proofs, while existing ethos with his concept of inartistic proofs.

Case 3 illustrates how a doctor can acquire ethos in a medical consultation. The example consists of a fragment of a Dutch paediatric consult in which the paediatrician is in the process of diagnosing a toddler with behavioural and developmental problems.

Case 3
Excerpt of an argumentative discussion between a doctor (D), who is a paediatrician, and the mother (M) of a toddler with behavioural and developmental problems

1. D: There’s, yeah, there’s a very small indication [that there is an anomaly] in that [the child’s] digestion, but they [the lab] say we can only determine or see that if we do an additional blood test.
2. M: But that, that it wouldn’t function well or, or, how do I erm…
3. D: Roughly speaking, erm, you have to think about that. That there’s a small mistake somewhere there in the digestion which, erm, could explain the problems. But, I’ve got to say, I think it’s but a tiny indication. I don’t think like “Oh, now, that’s fantastic; we’ve found something and, erm, we can work with that”. I’m like “Well, yeah, it’s an indication” and I’m like, well, god, if you do such a test and so you’ve already done those steps, and if they [the lab] advise that – it’s a good bunch that checks that – then I’d be tempted to do that in any case.

In case 3, the doctor implicitly puts forward the standpoint that the mother should let her daughter undergo an additional blood test: in turn 1, she asserts “They [the lab] say we can only determine or see that if we do an additional blood test” and she subsequently agrees with this by stating “I’d be tempted to do that in any case” in turn 3. From the reasons that the doctor provides for this advice in turn 3 (“If you get such a test, and so you already did those steps, and if they advise that – and it’s a good bunch of people that checks that”), it appears that the doctor assumes the mother is hesitant to adopt her advice – otherwise there would be no need for the presented argumentation.

In this consultation, the doctor acquires ethos by showing that she is knowledgeable about problems in the digestive system. After the mother indicates that she does not fully understand what it means for her daughter to have an anomaly in her digestion (“But that, that it wouldn’t function well or, or, how do I erm”, in turn 2), the doctor explains what such an anomaly could amount to (“there’s a small mistake somewhere there in the digestion which, erm, could explain the problems”, in turn 3) and tells the mother with how much certainty she can say the daughter suffers from this anomaly (“I think it’s but a tiny indication”, in turn 3).

The doctor, of course, also possesses existing ethos because of her medical knowledge. She, in fact, ‘acquires’ ethos in the consultation by making explicit that she possesses existing ethos. However, for the analysis, I shall consider making explicit existing ethos – or reinforcing existing ethos – as a way of acquiring ethos. Determining whether the acquired ethos is indeed grounded in a discussion party’s existing ethos is namely a matter for the evaluation, not the analysis – in fact, the evaluation needs to be conducted based on the analysis. As it is possible that the discussion party’s acquired ethos is not grounded in his actual existing ethos (for instance, because he is boasting), the ethos that he claims to have should not automatically be taken for granted in the analysis.

Furthermore, the doctor also acquires ethos by demonstrating that she is considerate in providing her advice (“I’m like “Well, yeah, it’s an indication” and I’m like, well, god, if you do such a test and so you’ve already done those steps, and if they [the lab] advise that – it’s a good bunch that checks that – then I’d be tempted to do that in any case”, in turn 3). By emphasising that, given the circumstances, it makes sense to let the child patient undergo an additional blood test, she demonstrates her practical wisdom – and appeals to that of the mother.

Additionally, by saying “I’d be tempted to do that in any case” (turn 3) the doctor makes explicit that she has the patient’s best interests at heart. If she herself would be tempted to let her own child undergo the additional test if she were in the mother’s position, then surely it is best to let the child patient undergo this test. The doctor’s earlier remark that “there’s a very small indication [that there is an anomaly] in that [the child’s] digestion, but they [the lab] say we can only determine or see that if we do an additional blood test” (turn 1) functions in the same way. It implies that the doctor has done everything in her power to examine whether there is an anomaly in the patient’s digestion, but the only way in which this can be determined for sure is by letting the patient undergo an additional blood test. In these contributions, the doctor can be said to build ethos by stressing her goodwill.

4. Argument from authority
Acquired or existing ethos should not be confused with authority argumentation. In authority argumentation, a discussion party presents the opinion of a supposed authority on the issue under discussion as a sign of the acceptability of his standpoint (van Eemeren and Grootendorst, 1992, p.163; and Garssen, 1997, p.11). The idea behind this type of argumentation is that the opinion referred to in the argumentation indicates the acceptability of the standpoint because the opinion shows that an authority on the discussion topic agrees with the standpoint in question. Figure 1 provides a representation of the argument scheme of authority argumentation.

Figure 1
The argument scheme of authority argumentation

1 – X is the case.
1.1 – Authority A is of the opinion that X.
1.1’ – A’s opinion indicates that X is the case.

In this scheme, the standpoint (1) “X is the case” is supported by the premises “Authority A is of the opinion that X” (the minor premise, 1.1) and “A’s opinion indicates that X is acceptable” (the major premise, 1.1’). In this scheme, X could be any proposition (descriptive, evaluative, inciting). An example of an authority argument would be: “I advise you to undergo psychosomatic physiotherapy, as I am sure you’ll benefit from it”. It should be noted that, in an authority argument, the authority referred to does not have to make explicit his opinion as such; instead, the opinion could be inferred from his behaviour, experiences, preferences, questions, remarks, etcetera. This is the case in the example: “I advise you to undergo psychosomatic physiotherapy, as I have very positive experiences with it”.

From a pragma-dialectical perspective, authority argumentation is a subtype of the main type of symptomatic argumentation (van Eemeren & Grootendorst, 1992, p. 163; Garssen, 1997, p. 11). In symptomatic argumentation, a discussion party presents that which is claimed in the argument as a sign of that which is claimed in the standpoint. For authority argumentation, this main scheme can be specified by regarding the authority’s opinion as the sign of the acceptability of the standpoint.

By presenting premises 1.1 (“Authority A is of the opinion that X”) and 1.1’ (“A’s opinion indicates that X is the case”) of an authority argument, the discussion party performs the speech act of asserting.[iii] To felicitously perform this speech act, the discussion party needs to fulfil the sincerity condition that he believes the asserted proposition to be true (Searle, 1969, pp.66-67). A discussion party who presents authority argumentation can, hence, be held accountable for believing that the supposed authority really possesses authority on the subject matter and can be held accountable for viewing this authority’s opinion as a sign of the acceptability of the standpoint. He therefore needs to take on the burden of proof for these premises if the antagonist indicates doubt about or opposition to them (“Tell me why you are an authority on this matter” or “But why does this prove your point?”).

Herein lies the difference between authority argumentation on the one hand, and acquired and existing ethos on the other. In contrast to an authority argument, a discussion party’s ethos does not support a specific (sub-)standpoint. The party’s ethos is, in fact, potentially persuasive on all levels of the argumentation, influencing the effectiveness of every proposition that he puts forward. For that reason, a discussion party does not have a burden of proof for the justificatory force of his ethos. After all, he does not claim that his ethos is a sign of the acceptability of the standpoint. This is in stark contrast with the burden of proof that a discussion party has for authority argumentation, since he commits himself to the premise “Authority A’s opinion indicates that X is the case” by presenting this argument.

In the extant literature, the authority that a discussion party refers to in an authority argument is typically an external source – such as an expert in the field, a dictionary or an official institution (Walton, 1997, pp. 63-90). The argument takes the form “He should change his diet, because the dietician said so and, if a dietician says so, then that must be the case”. In case 3, the doctor presents such an authority argument. In this consultation, the doctor refers to the advice of the laboratory in support of the standpoint that the child patient should undergo an additional blood test (“They [the lab] advise that – it’s a good bunch that checks that” in turn 3). Figure 2 provides a reconstruction of this argument.

Figure 2
Reconstruction of the doctor’s argument from authority in case 3

(1) – (You [the mother] should let your daughter undergo an additional blood test.)
(1).1 – They [the lab] advise that.
((1).1’) – (If the lab advises you to let your daughter undergo an additional blood test, then you should let your daughter undergo this test.)

Following the pragma-dialectical terminology for authority arguments in which the referred to authority is an external source, I shall call these arguments more specifically ‘arguments from authority’ (van Eemeren and Grootendorst, 1992, p. 163; Garssen, 1997, p. 11).

5. Argument by authority
Instead of referring to an external source in an authority argument, a discussion party can also present himself as the authoritative source in this type of argumentation. For instance, in the authority argument in case 4, the doctor refers to himself as the authority. The example is taken from a consultation about, amongst other things, the patient’s atheroma cyst (a slow-growing, non-cancerous tumour or swelling of the skin) in a Dutch general practice.

Case 4
Excerpt of an argumentative discussion between a doctor (D) and a patient (P) about the removal of the patient’s atheroma cyst;

1. P: And then I wanted to ask something else right away.
2. D: Yes?
3. P: Is it possible to get a referral note to the hospital for that lump on my head or, ehm, do I just have to let it be done by you here?
4. D: Well, you don’t have to do anything, but …
5. P: No, the point is, yeah, my mother had had it removed in the hospital and she says ‘Dear, go to the same, it …’
6. D: I think that I can do it just as well as and perhaps even better than those people at the hospital. It was such a, such a, such an atheroma cyst on your head, wasn’t it?
7. P: Yeah, it becomes yes, my mother, she, ehm, she brings it up every day of course…
8. D: Well …
9. P: Yes …
10. D: You don’t have to let it be removed by me, but I’m telling you, to be sure, I can do it just as well as someone at the hospital. I’ve removed a dozen of those things and it’s, in itself, a piece of cake.
11 P: Yes.

In case 4, the doctor implicitly advises the patient to let the atheroma cyst on his head be removed by the doctor himself, rather than at the hospital. Even though the doctor does not present his advice explicitly – he, in fact, emphasises that it is up to the patient to decide by whom to let the cyst be removed (turn 4) – the doctor’s advice can be inferred from his reactions to the patient’s request for a referral note (turn 3). The doctor points out that there is no need for such a referral: he could perform the surgery “just as well as and perhaps even better than” they could do at the hospital (turn 6). The doctor indeed argues that he has a lot of experience with removing atheroma cysts (turn 10).

The doctor’s argument that he could remove the atheroma cyst just as well as and perhaps even better than the people at the hospital constitutes an authority argument. The doctor namely explicitly emphasises his expertise in removing the atheroma cyst in support of the advice that the patient should let him remove the cyst, thereby presenting his authority on this matter as an indication of the acceptability of his advice.[iv] The argument can be reconstructed as follows (figure 3).

Figure 3
Reconstruction of the doctor’s argument by authority in case 4

(1) – (It is advisable to let me [the general practitioner] remove the patient’s atheroma cyst.)
(1).1 – I can remove an atheroma cyst just as well as, and perhaps even better than, people at the hospital.
((1).1’) – (If I can remove an atheroma cyst just as well as, and perhaps even better than, people at the hospital, then the patient should let me remove his atheroma cyst.)

The authority argument in case 4 differs from the argument from authority in case 3. In case 4, the doctor refers to his own authority, whereas, in case 3, she refers to the authority of an external source (“the lab”). In order to accurately analyse these different forms of authority argumentation, I shall distinguish between them by using the term ‘argument by authority’ exclusively for the kind of authority argumentation in which the authority referred to is the discussion party that presents the argumentation (as in case 4) and ‘argument from authority’ exclusively for the kind in which the authority referred to is a source outside of the discussion (as in case 3).

6. Authority in practice
The distinction between existing ethos, acquired ethos, the argument from authority and the argument by authority is an analytical one, meaning that it is necessary for an adequate analysis of (the use of) authority in argumentative discourse: by using this distinction, it can be analysed how the authority of a particular source influences the discussion outcome. In turn, this analysis provides the basis for the soundness evaluation of (the use of) authority. For example, analysing a discussion contribution as an argument by authority means that the discussion party can be held accountable for claiming that his authority indicates the acceptability of his standpoint. As a consequence, evading the burden of proof for this claim should be evaluated as fallacious.

In practice, the analytically distinct ways in which authority can influence the outcome of an argumentative discussion might coincide. For example, in case 1b, which is a continuation of the argumentative discussion between the doctor and patient from case 1a, the doctor acquires ethos by affirming part of the existing ethos that the patient ascribes to him.

Case 1b
Excerpt of an argumentative discussion between a doctor (D) and a patient (P) about the patient’s possible inguinal rupture

4. P: No, no, but I thought that doctors could feel that [an inguinal hernia] just like that.
5. D: If it really is a big fracture, then you can see it just like that.
6. P: Yeah.
7. D: I mean, then, then I can do it with my eyes closed.
8. P: Oh.
9. A: But if something is really small, then you sometimes just miss it. So it’s a doubtful case then. But okay, so you keep having problems with it and we don’t actually know what it is, because I haven’t felt that it was a fracture for sure. If it were a clear fracture, then I’d have felt it. True.

In case 1b, the patient makes clear that he expected doctors to be able to simply feel an inguinal hernia by means of a physical examination in the consultation (turn 4). So, he believes the doctor’s existing ethos to consist of the expertise to constitute whether a patient suffers from an inguinal rupture. In reaction to this, the doctor plays down the extent to which doctors possess expertise on this issue: they cannot always diagnose such a rupture with certainty (“But if something is really small, then you sometimes just miss it. So it’s a doubtful case then”, turn 9). The doctor nonetheless affirms that, in case of a big fracture, they can “see it just like that” (turn 5) or, at least, he can (“I mean, then, then I can do it with my eyes closed”, turn 7). The doctor, thereby, reinforces the idea that he is competent on diagnosing inguinal hernias. This reinforcement can be analysed as a way of acquiring ethos; after all, the doctor does not simply depend on his existing ethos, but feels the need to stress this ethos by stating he can diagnose a big inguinal rupture with closed eyes. Thus, the doctor’s existing ethos and acquired ethos coincide. In fact, for acquired ethos (and also for an argument by authority), it is imperative that the discussion party possesses the authority that he claims to have in the discourse. Since this authority can be reconstructed as his existing ethos, the party needs to possess the acclaimed existing ethos for convincingly arguing by authority and using acquired ethos.

The analytical distinction between the ways in which authority can influence discussion outcomes can, in practice, also be blurred because a discussion party can acquire ethos by presenting an argument by authority or an argument from authority. In case of an argument by authority, the discussion party’s authority as referred to in the argument could influence the acceptability of his later contributions to the discourse, even though the discussion party does not specifically present his authority in support of them. The doctor’s argument “I advise you to undergo psychosomatic physiotherapy, as I have very positive experiences with it” could, for instance, function in this way. Before the doctor presents this argument, the patient might not be aware of his experience with psychosomatic physiotherapy. In such a situation, the argument brings the doctor’s experience to light, which can positively affect the doctor’s subsequent contributions (“With all his experience, he must know what he’s talking about”).

In case of an argument from authority, the fact that the discussion party refers to the authority of an external source could acquire ethos in a similar manner. The party can show that he is knowledgeable (“I’m familiar with the work of Aristotle”) or that he is well connected (“I know these experts”) by presenting an argument from authority (“The practice of medicine should be regarded as a practical art, since Aristotle considered it as such” or “The bird flu virus can cause a worldwide pandemic, as my colleagues from virology showed at our research colloquium”).

Although the ways in which authority can influence a discussion outcome can overlap in practice, it is necessary to analytically separate them. Each way provides the discussion party with distinct possibilities for strategic manoeuvring, due to differences in directness and the burden of proof it places on the party. These differences should be made clear to adequately evaluate the soundness of (the use of) authority in argumentative discourse.

7. Conclusion
In this chapter, I proposed a fourfold analytical distinction between the ways in which authority can influence the outcome of an argumentative discussion. These ways are outlined in figure 4.

Figure 4
Four ways in which authority can influence the outcome of an argumentative discussion:

Existing ethos: The discussion party’s authority that is in place at the start of the argumentative discussion.

Acquired ethos: The discussion party’s authority that he constructs during the argumentative discussion, but that he does not present in support of a specific (sub-)standpoint.

Argument from authority: The argument in which a discussion party refers to an external source’s authority to support a specific (sub-)standpoint.

Authority in practice: The argument in which a discussion party refers to his own authority to support a specific (sub-)standpoint.

Based on this fourfold distinction, the doctor’s authority on medical matters can be expected to influence the outcome of an argumentative discussion in medical consultation in the following ways. First of all, the doctor’s existing ethos can positively influence the patient’s evaluation of his argumentation about the health problem at issue. After all, the patient regards the doctor as an authority on health problems – otherwise he would not have requested a consultation by the doctor. Additionally, the patient might ascribe existing ethos to the doctor because of the doctor’s status as a medical professional. Secondly, the doctor can acquire ethos during the medical consultation. By his discussion contributions, he might, for instance, demonstrate that he is trustworthy or that he possesses the necessary medical knowledge and expertise to deal with the patient’s health problem. Thirdly, the doctor can refer to his authority to make a medical advice (or parts thereof) acceptable by means of an argument by authority. The doctor then presents his authority as an indication of the acceptability of the medical advice or parts thereof.

Acknowledgements
I would like to thank Frans van Eemeren and Nanon Labrie for their help. The proposed fourfold distinction is based on personal communication with Frans van Eemeren, and Nanon Labrie drew my attention to the medical consultation of case 1a and 1b.

NOTES
i. The examples in this contribution are obtained from the database compiled by the Netherlands Institute for Health Services Research (transcriptions and translations from Dutch, RP).
ii. The doctor’s assurance can, therefore, be reconstructed as an attempt to (re-)establish her ethos. In the next section, I shall analyse (re-)established ethos as ‘acquired ethos’.
iii. In practice, a discussion party does not always make both premises explicit. If one of them is left implicit, it can be made explicit based on the concept of logical validity and pragmatic principles (van Eemeren & Grootendorst, 1992, pp.60-72). The unexpressed element is, then, reconstructed as an indirect assertion, to which the discussion party can be held committed.
vi. The doctor also draws a comparison between the medical professionals at the hospital and himself (“just as well as and perhaps even better than”). As the comparison is part of the authority argument and I focus on the way in which the authority argument supports the standpoint, I shall refrain from analysing this comparison.

References
Aristotle. Ars rhetorica [The art of rhetoric]. Trans. Lawson-Tancred, H.C. (2004). London: Penguin Books.
Council Directive 93/16/EEC of 5 April 1993 to facilitate the free movement of doctors and the mutual recognition of their diplomas, certificates and other evidence of formal qualifications. Retrieved from http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31993L0016:EN:HTML on 9 September 2014.
Eemeren, F.H. van, & Grootendorst, R. (1992). Argumentation, communication, and fallacies: A pragma-dialectical perspective. Hillsdale: Lawrence Erlbaum Associates.
Garssen, B.J. (1997). Argumentatieschema’s in pragma-dialectisch perspectief: Een theoretisch en empirisch onderzoek [Argument schemes from a pragma-dialectical perspective: A theoretical and empirical investigation]. Amsterdam: IFOTT.
Helmes, A.W., Bowen, D.J., & Bengel, J. (2002). Patient preferences of decision-making in the context of genetic testing for breast cancer risk. Genetics in Medicine 4, 150-157.
Pilnick, A., & Dingwall, R. (2011). On the remarkable persistence of asymmetry in doctor/patient interaction: A critical review. Social Science & Medicine 72, 1374-1382.
Searle, J.R. (1969). Speech acts: An essay in the philosophy of language. Cambridge: Cambridge University Press.
Tindale, C.W. (2011). Character and knowledge: Learning from the speech of experts. Argumentation 25(3), 341-353.
Walton, D. (1996). Argument schemes for presumptive reasoning. Mahwah: Lawrence Erlbaum Associates, Inc.
Walton, D. (1997). Appeal to expert opinion: Arguments from authority. University Park: The Pennsylvania State University Press.