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Placebo treatments, informed consent and ‘the grip of a false picture’
  1. Shane Nicholas Glackin
  1. Correspondence to Dr Shane Nicholas Glackin, Department of Sociology, Philosophy, and Anthropology, University of Exeter, Rm 350, Amory Building, Rennes Drive, Exeter EX4 4RJ, UK; shane.n.glackin{at}


It is widely supposed that the prescription of placebo treatments to patients for therapeutic purposes is ethically problematic on the grounds that the patient cannot give informed consent to the treatment, and is therefore deceived by the physician. This claim, I argue, rests on two confusions: one concerning the meaning of ‘informed consent’ and its relation to the information available to the patient, and another concerning the relation of body and mind. Taken together, these errors lead naturally to the conclusion that the prescription of placebos to unwitting patients is unethical. Once they are dispelled, I argue, we can see that providing ‘full’ information against a background of metaphysical confusion may make a patient less informed and that the ‘therapeutic’ goal of relieving the patient of such confusions is properly the duty of the philosopher rather than the physician. Therapeutic placebos therefore do not violate the patient's informed consent or the ethical duties of the doctor.

  • Autonomy
  • Informed Consent
  • Philosophical Ethics
  • Philosophy of Medicine
  • Truth Disclosure

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It is widely supposed that the prescription of placebo treatments to patients for therapeutic purposes (rather than in the context of placebo-controlled trials) is ethically problematic on the grounds that the patient cannot give informed consent to the treatment.i This claim, I argue, rests on two confusions; once these are dispelled, it can be maintained only by taking an implausible view of the physician's duties, qua physician, to the patient.

The first confusion primarily affects theorising about the meaning of ‘informed consent’, and has to do with the relation between information and informedness. The second affects both the patient purportedly ‘deceived’ by receiving a placebo treatment and those of us who speculate about his or her decision-making, and it concerns the relation of body and mind. Taken together, they lead naturally to the conclusion that the prescription of placebos to unwitting patients is unethical; however, as I shall show, they are both false.

There are some similarities between my approach and that recently advanced by Gold and Lichtenberg in these pages;4 however, there are also significant differences. While both views target ‘Cartesian’ accounts of the mind–body relation, mine is concerned specifically with an underlying Cartesian intuition, rather than with any particular theoretical position. And whereas Gold and Lichtenberg distinguish between lying and deceiving a patient in order to defend a virtues-based paternalism against concerns about patient autonomy, my approach denies that any such deception, or violation of autonomy, takes place.

I begin by briefly sketching the main ethical case against placebo treatments, to which my argument responds. Following this sketch, I discuss in turn the two confusions which the case involves before examining the remaining duties towards her patient which a physician could reasonably be thought to break by the provision of placebo treatments.

For purposes of argument, I assume here that at least some placebo treatments are efficacious in at least some circumstances. This is not uncontroversial. Likewise, while the conceptual soundness of the term ‘placebo’ has been forcefully challenged,2 ,3 ,5 ,6 I do not address those concerns in the present paper; my analysis here focuses on the concepts of information and informed consent as they pertain to placebo treatments, rather than on the placebo concept itself.

The case against placebo treatments

The American Medical Association is unambiguous in condemning the prescription of placebos to unwitting patients; the physician may administer a substance that ‘has no specific pharmacological effect upon the condition being treated … for diagnosis or treatment only if the patient is informed of and agrees to its use.’7 Such treatments are widely regarded as deceptive, and therefore as infringing on the autonomy and informed consent of the patient.8 In Britain, the House of Commons Select Committee on Science and Technology likewise concluded that placebo treatment ‘removes informed patient choice, because the patient is being asked to make decisions under false pretences’, rendering that choice ‘meaningless’.9 Nevertheless, these conclusions have been challenged,4 ,10–12 and the practice of physicians reflects reasonably widespread ethical approval: 62% of US rheumatologists and internists responding to a recent survey believed the practice to be permissible, 3%–5% reported administering such treatments on a regular basis, and only 5% of those explicitly described them to patients as placebos when doing so.13 In the UK, 12% of general practitioners report using ‘pure’ placebos at least once in their career, and 1% at least once per week; 66% regarded the practice as ethical.14 ii

The objections revolve around the familiar principle of informed consent or the notion, first explicitly articulated in Salgo v. Leland Stanford, Jr. University Board of Trustees,15 that a patient must ‘with substantial understanding and in substantial absence of control by others, intentionally [authorise] a health professional to do something’ before any such procedure can be carried out.16 The reasoning is not hard to see; if I am not told, as a patient, that the proposed treatment is pharmacologically inert, then I am not in an epistemic position to consent to being administered such a substance. A salient piece of information, which we have good reason to think might affect my decision, has been consciously withheld from me by my physician. I therefore lack, in making my decision, substantial understanding of the treatment; arguably, too, I lack substantial absence of control by another, since my doctor is manipulating my decision by restricting information in this way.

Put this way, the argument is an intuitively attractive one, and closely parallels a central line of reasoning in Kant's ethics. As he argues in the Groundwork of the Metaphysics of Morals, a lying promise is not possible under the Formula of Humanity, since ‘the man whom I seek to use … by such a promise cannot possibly agree with my way of behaving to him, and so cannot himself share the end of the action.’17 In the placebo case, we may presume that the patient does share the doctor's end, which is to treat him, or at least to relieve his symptoms; nevertheless, the argument goes, it is impossible for him to agree with the treatment, since by definition he does not know what it is he is agreeing to.

Defenders of placebo treatments have tended, in the main, to reject this deontological reasoning and to argue that such violations of informed consent as are involved in their prescription are morally justified in view of other considerations and that patient autonomy is therefore not a moral absolute.4 ,10 ,12 ,18 Nevertheless, physicians’ intuitions do not appear to support such claims: 82% of British general practitioners reported that they believed placebos to be ethically unacceptable when they involved deception.14 I have no wish to further prosecute the venerable debate between deontological virtue-theoretic and consequentialist views of ethics here; what I wish to demonstrate is that even deontological arguments against deception of a patient do not preclude placebo treatments, properly understood.iii

Accordingly, I will not attempt here to refute a second influential and widely held14 line of ethical argument against placebo treatments, which concerns the resulting potential for a breakdown of trust between patients and physicians.6 ,11 This seems to me a significant objection, but not one that establishes the moral impermissibility of placebo treatments. As a piece of consequentialist rather than deontological reasoning, what it shows instead is that physicians must carefully and cautiously weigh up the pros and cons of prescribing placebo treatments in individual circumstances; it does not forbid placebo treatments as such. Indeed, it will not affect the reasoning of a physician who considers himself or herself morally obliged to treat a particular patient in this way. Moreover, if the argument I make in this paper becomes better and more widely understood, the potential for a breakdown in trust as a result of such treatments will be reduced.

In what follows, I shall contend, first, that the concern about deception of the patient is misguided, and that the withholding of information in this way may in fact raise the level of informedness with which the patient consents to treatment and, second, that in cases where the patient would have decided differently given the information that the proposed treatment was a placebo, withholding the information would indeed have raised his or her level of informedness.

Having more information is not being more informed

It is natural to assume a simple grammatical relationship between information and informedness; to provide somebody with information is to inform them, and to be informed is to have been provided with information. It is a natural assumption, but—at least as the term is meant in the phrase ‘informed consent’—it is a false one.

What we require for informed consent, recall, is ‘substantial understanding’ of the procedure in question. But of course, simply gaining some pertinent extra datum does not necessarily increase one's understanding and in some cases it may reduce it, by causing (or exacerbating) confusion. ‘Raw’ scientific data, Sabina Leonelli demonstrates, are neither true nor false in themselves, but require interpretation in the context of particular scientific theories.20 More generally, as David Lewis has pointed out:(e)xplanatory information may be provided in such a way that the recipient has difficulty in assimilating it, or in disentangling the sort of information he wants from all the rest. He may be given more than he can handle, or he may be given it in a disorganized jumble. Or he may be given it in so unconvincing a way that he just doesn't believe what he's told. If he is hard to convince, just telling him may not be an effective way to provide him with information.21

There are numerous ways, then, in which being provided with relevant information may nonetheless fail to inform us. Not every piece of information we can give to a patient will contribute positively to his or her substantial understanding of the proposed treatment for which consent is required.

In some circumstances, against a background of false beliefs, extra information may have a negative effect on our overall understanding. To take a toy example, suppose that I am visiting the UK, maps of which I have spent my life unwittingly looking at upside-down, and wrongly believe London to be several hundred miles north of my current location in Edinburgh. Wishing to drive to London to speak at a conference, I enquire of a passer-by which direction is north. But though he tells me truthfully, this information does not help me find my way to London to give my talk; in fact, it only deepens my confusion.

Throughout the Philosophical Investigations, Ludwig Wittgenstein constantly refers to the idea of being ‘held captive’ by ‘a picture’.22 ‘Pictures’, in this sense, are particular ways of understanding the world, often useful or fruitful in a limited range of application, but which lead us astray when, as we are prone to do, we apply them too widely.23 It is ‘in the grip’ of these false pictures, these systematically misleading conceptions of the world, that gaining new information is most likely to further diminish our understanding of the situation; the duty of a philosopher, on this view, is therefore the ‘therapeutic’ one of releasing their hold on us and allowing us to see these representations of the world as merely particular cognitive tools appropriate to particular contexts of reasoning.24

As I shall now argue, much of the sense of impropriety which is felt about ‘deceiving’ a patient by the prescription of placebo treatments derives from just such a false picture of the relation between mind and body. In particular, the idea that the patient would have chosen differently if told the treatment was pharmacologically inert depends on the assumption that the patient is himself or herself in the grip of that picture. Not only is that picture demonstrably false, I will go on to show, but the ‘Wittgensteinian therapy’ of loosening its grip is not properly the concern of the physician.

The false picture of ‘naïve Cartesianism’

As a matter of routine, doctors do not tell patients the biochemical details of how and why their treatments work. Patients receiving ibuprofen are not told about cyclo-oxygenase inhibition nor those receiving penicillin about DD-transpeptidase catalysis rates. Nobody, I think, sees anything untoward about this; the great majority of patients simply lack the background knowledge necessary to make sense of this information. It is not the responsibility of doctors, moreover, to remedy this lacuna in their understanding.

68% of physicians who administer placebos report describing them to patients as some variation of ‘a medicine not typically used for your condition but [which] might benefit you.’13 An alternative, and more fastidious, locution which has been suggested in the literature is ‘I would like to offer you a pill which I believe can help lessen your suffering. I do not know exactly how it works. I have other pills to offer whose mechanism is clearer, but I am not sure that they will work better for you, and they may also entail more serious side effects.’12 Both of these descriptions are plainly true, but are widely regarded as nevertheless deceptive, since they withhold the information that the pill or medicine is pharmacologically inert. But as noted above, it is entirely normal for physicians to leave out details about the precise causal pathways by which medicines work. So what, exactly, differentiates placebo cases from more conventional prescriptions?

One possible answer might be that we have reason to think the patient will not consent if informed the treatment is a placebo, whereas that is less likely to happen in more standard cases. Thus, by deliberately withholding information relevant to the decision, the doctor violates the Gricean ‘Maxim of Quantity’ and thereby wrongfully implies that the treatment is an active one.25 iv But, if true, this response only postpones the issue; we are still left with the question of why patients might refuse inert treatments.

For both questions, the explanatory intuition seems to be connected with a sense of deception or trickery, an association which even proponents of placebo treatments have sometimes conceded; see e.g. the titles of these references.10 ,11 ,18 ,26 The placebo does not act on the body, on this view, but merely ‘fools’ the mind into believing that the body has been treated, thereby causing it to trigger or accelerate the body's own supplementary healing mechanisms.

This dichotomy, between acting on the patient's body and ‘merely’ acting on his or her psyche, is an intuitively appealing one. However, it results from what, following Wittgenstein, we may term a false picture of the mind–body relation. What it presumes is that there is a total causal separation between the mind and body, such that acting on the mind is not thereby also acting on the body. Call this picture ‘naïve Cartesianism’.

The notion of a ‘Cartesian fallacy’ or ‘an outmoded Cartesian prejudice’ underpinning the antiplacebo case has been raised elsewhere in the literature.4 ,12 By referring to naïve Cartesianism, however, I wish to emphasise explicitly that the picture in question is not part of any contemporary theoretical position. That is, to sustain the argument I am making, we need not reject sophisticated modern versions of mind–body dualism like David Chalmers;27 and their adherents are likewise not committed to the moral impermissibility of placebo treatments. For those who believe in any form of mind–brain identity, naïve Cartesianism is clearly false; acting on the mind is acting on the brain, and the brain is assuredly part of the body. But for those more sympathetic to dualist reasoning, this ‘folk’ version of the theory is similarly plainly false. Indeed, no further demonstration of its falsehood is necessary than the very fact that placebos work. The placebo may have no direct pharmacological effect, but it has a measurable and observable indirect one, mediated by complex biopsychosocial mechanisms that we do not as yet understand very well.28 One thing we do know about the mechanisms: they do not seem to be dependent on trickery, or ‘fooling’ the mind, since—again—placebos seem to be at least somewhat effective even when the patient is informed.1

The suggested locutions are therefore perfectly accurate; the treatment is known to relieve symptoms, and we are not really sure why, or what the causal pathways are. This is the basic information which the patient requires to make an informed decision and given the prevalence of belief in the naïve Cartesian picture, further information is not only superfluous, but is apt to actively misinform the patient as to the nature and effect of the treatment.

What doctors do and what philosophers do

The root of the Kantian case against false promising, we saw, was that the promisee cannot possibly consent to be deceived, and so cannot share the promissor's ends. We have defused the first part of this worry as it applies to placebo treatments: that the treatment is pharmacologically inert is a merely incidental part of what the patient is asked to consent to, at a level of causal detail far beyond what she standardly needs to understand her decision. By way of insurance, though, we can also disregard the second part of the Kantian worry: the ends of the doctor in most circumstancesv are exactly those of the patient. ‘The central aim of medicine is making people better,’ as the House of Commons report quoted above held,9 and in this respect there seems to be no real worry about the deception resulting in a use of the patient merely as a means to the doctor's own ends. This enables us to establish counterfactual consent to treatment by placebo. That is, even if we take its placebo nature to be an essential feature of the treatment, given the aim of getting better the patient would have consented to the treatment as long as he or she were in possession of all relevant information, including the falsity of naïve

But even if we know intellectually that the naïve Cartesian picture is false, it is no easy matter to shake its intuitions. This is what Wittgenstein means by being held captive or ‘caught in the grip’ of such pictures; they are not merely propositions or descriptions of the world, with which we may agree or disagree, but are buried deep in our understanding of the world, and in the grammar of our language for talking about it. The proper role of the philosopher, Wittgenstein therefore holds, is in its own fashion therapeutic; it is to diagnose the resilient metaphysical confusions which afflict us, and to relax their grip, allowing us to ‘go on’ in the world, untroubled by philosophical perplexities.

But this ‘therapy’ is very different in its content from that pursued by the doctor. The whole duty and aim of the doctor qua doctor is, again, to make the patient better. Correcting the patient's metaphysical errors is no part of the doctor's duties and it is probably not high on a sick patient's list of priorities either. That is to say, a doctor who sought to assuage his or her conscience by fastidiously ensuring that the patient's consent is fully informed would end up thwarting the patient's ends in the matter just as surely as one who failed to prescribe what he or she considered to be the best available treatment due to the supposed logical impossibility of the patient's consenting to being deceived.

Leaving it to the physician to decide how much information a patient needs looks, of course, very much like paternalism and despite the enthusiasm of some pro-placebo ethicists,2 ,10 paternalism is not widely favoured in contemporary medical ethics. Does the argument made here thereby readmit paternalism ‘by the back door’?vii If so, I think it is a relatively innocuous, second-order or ‘epistemic’ form of paternalism: the doctor is not asked to make an evaluative judgement about what is best for the patient, but a factual one about which information will render the patient more informed and which not.

The duty of the physician is to treat the patient as efficaciously as possible, subject to the patient's informed consent to the treatment. Where, in the doctor's judgement, the best treatment is a placebo, withholding the fact that it is inert does not violate the patient's informed consent. Either the fact would simply have been irrelevant to the patient's decision-making process, or—if the patient was in the grip of the naïve Cartesian picture—it would have reduced the level of the patient's informedness, and the quality of consent.


I am grateful to Sinéad Glackin, Michael Hauskeller, Martha Henriques, and Louisa Owens, among others, for their helpful discussion of these issues, as well as to two anonymous reviewers for this journal for their comments and suggestions, all of which improved my arguments significantly.



  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • i For the purpose of isolating the ethical issue, I will disregard the growing evidence that even ‘open’ placebos, where the patient is fully aware of their inert nature, can be efficacious.1 I will also limit the discussion, for purposes of conceptual clarity, to ‘pure’ placebos. While physicians sometimes prescribe so-called ‘impure’ placebos—substances which are not pharmacologically inert but have no known effect on the patient's specific condition—the soundness of this concept has been disputed.2 ,3 I therefore discuss only ‘pure’ placebos in what follows, and reserve judgement about whether the arguments are similarly applicable to a wider class of treatments.

  • ii It should be noted that these empirical studies have been criticised in the literature.2 ,3 Nevertheless, the ethical and conceptual issues discussed here are worth pursuing even if the actual use of placebo treatments turns out to be very rare indeed.

  • iii The argument thus also obviates the felt need for ‘negatively informed consent’ as an alternative to informed consent in placebo cases.19

  • iv On this understanding, the distinction drawn by Gold and Lichtenberg4 and Cohen and Shapiro,26 among others, between ‘lying’ and ‘deceiving’ would be seen as insignificant from the perspective of linguistic pragmatics, and thus as rather shaky ground on which to build an ethical defence of clinical placebo use.

  • v Of course, we can imagine a situation where the doctor prescribes a placebo so as to, e.g. get a troublesome or annoying patient off his back.12 I do not refer to such cases.

  • vi So-called ‘Full Information’ accounts of value are an influential branch of contemporary meta-ethics.29

  • vii I thank an anonymous referee for pressing this concern.

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