Bioethics and Bad Reasoning: The Slippery Slope of Using Slippery Slope Arguments

Slippery Slopes and Euthanasia

A ‘slippery slope argument’ (SSA) is a particular style of argument which particularly raises my ire (a phrase I’ve always wanted an excuse to employ) as they are so often raised against points I am trying to make, but also worries me in the frequency and potency of its use. These arguments are used to disrupt or even halt debate on some particularly controversial and important themes, and – tragically – are often simply accepted at face value, as they seem powerful at first glance, but perhaps do not stand up to logical scrutiny. In its most basic form, the Slippery Slope Argument suggests that if we allow position A to come about then it is highly likely, even certain, that, through some direct or indirect connection, position Z will eventually also come about.[1] However, the validity of many of these arguments is questionable at best; David Enoch goes as far as to point out that they are often referred to as ‘slippery slope fallacies’.[2] Nonetheless, these types of argument have been used in the legal, philosophical and political spheres for many years and in debates ranging from conspiracy theories about a One World Government[3] to the question of stricter firearms control in the US[4] to discussion about abortion law reform.[5] A key aspect of SSAs is that position A is often regarded as not inherently wrong, or at least not nearly as wrong as Z, and yet it is argued that A should not be allowed happen because it may lead to Z – the primary reason for prohibiting A itself in fact has very little to do with the characteristics of A alone.

To illustrate many of the problems with using SSAs we can take the controversial area of euthanasia, in which just such arguments are frequently employed. The term “euthanasia” itself is a often confusing and disputed one, but briefly summarised, the types of procedures talked about are; Physician Assisted Suicide (PAS), in which the patient performs the final act themselves; Voluntary Active Euthanasia (VAE), also known as ‘physician accomplished suicide’, in which the doctor or other third party performs the final act; Non-Voluntary Active Euthanasia (NVAE), where the patient is unable to consent due to permanent or temporary incompetence; and finally Involuntary Active Euthanasia (IVAE), the most controversial of all – where the patient is able to consent but has not. The final three are often referred to simply as ‘euthanasia’ as they involve an active role rather than the passive role of PAS or withdrawal of treatment.[6] Many opponents of “euthanasia” will admit that they have little against  PAS,[7] or even limited cases of VAE, in principle, however they see an unacceptable risk of these actions being legalised leading to NVAE and IVAE being accepted as the norm and society descending into one where the old or infirm were coerced, even forced, into euthanasia. The most extreme end-result  suggested by this particular slippery slope argument is often considered to be something akin to the Nazi forced euthanasia program.[8]

One of the primary and best proponents of the SSA against assisted dying and euthanasia is John Keown.[9] Indeed it is his relatively clear and well reasoned version of the argument that Stephen W. Smith[10][11] takes issue with in his critiques of the uses of both logical and practical SSAs in this debate. Keown raises two primary concerns about legalising any form of assisted dying or euthanasia: Firstly, that if PAS and VAE are legalised then NVAE and IVAE may also become acceptable; and secondly, that apart from leading to other forms of euthanasia, such acceptance of PAS and VAE might lead to them being considered a more frequent form of treatment and no longer merely a last resort.[12]

Keown seems to suggest that the “opening of the floodgates” will mean that PAS and VAE easily allow for a move to involuntary and non-voluntary euthanasia. This strikes this author as quite a leap, whatever the statistics in countries with types legalised euthanasia, such as the Netherlands, might show. Many people (myself for one) could accept PAS and VAE being introduced, but would very much hesitate at even a slight move towards NVAE or IVAE. Perhaps where there was a valid living will or advance directive or very compelling evidence that such was the patient’s wishes (remember, many cases of this sort may fall within the ambit of medical futility or refusal of treatment) the issue may be ‘considered’. But that is a far cry from saying the former two practices lead to acceptance of the latter two. One of the primary arguments in favour of allowing PAS and VAE is personal autonomy, which cannot work as an argument in favour of NVAE or IVAE – quite the opposite.

Smith references statistics showing very little difference between attitudes of doctors in the US and Netherlands regarding PAS and Euthanasia,[13] which goes against the argument that a change in law has forced a change in attitude towards these practices;

“Moreover, the difference in attitude about the patient who believes he or she is a burden suggests the Dutch physicians have a stricter standard about PAS than their US counterparts. This might suggest that instead of making physicians have a less strict attitude towards the value of life, the regulations in the Netherlands have actually increased physicians’ desires not to endorse practices that are more morally suspect.”[14]

He goes on to analyse much of the evidence for a practical slippery slope in the Netherlands and the impression is that doctors’ and the public’s attitudes remain either unclear or changeable at best, but certainly not definite evidence of a devaluing of human life. On a practical note he states “there does not appear to be any evidence from the three Dutch studies that shows that doctors are more frequently using non-voluntary or involuntary euthanasia in the Netherlands” and if fact points out that one study indicated Australia and Belgium had higher rates of NVAE or IVAE, with an inter-European survey showing similar results.[15]

In one argument for the ‘logical’ slippery slope Keown plays down the importance of autonomy, essentially saying that the doctor will always be making the critical decision in a euthanasia or assisted dying situation because although the patient might initiate the request, the doctor still has to decide on its legitimacy.[16] He worries this means there is little logical distinction between VAE and NVAE or IVAE. David Price points out that;

“Lillehammer however maintains that Keown’s argument is specious and founded upon a logical confusion, a misunderstanding of the value of autonomy, or both. He argues that voluntary euthanasia may be seen to rest upon an autonomous request in conjunction with the doctor’s judgment, i.e. they are both necessary though not sufficient elements of a valid instance of euthanasia, and thus only the empirical slippery slope remains to be countered.”[17]

Keown fails to take into account that because the doctor has an intervening decision it does not follow that theirs becomes the ultimate decision to end the life. Why would the doctor’s intervening decision cause them to be the ultimate decider but the patient retaining a veto up to the very end for VAE and performing the actual deed in PAS not also intervene to deem them the ultimate decider once more? The only cases in which this might be a reasonable risk are with NVAE or IVAE, but Keown has the cart before the horse if that is the case, as his argument suggests that this will lead to NVAE or IVAE, which cannot be so if they are the only two where it might play out.

The necessity to acknowledge the involvement of both the  doctor and patient is also addressed by Smith in his critique of the logical SSA.[18] He then addresses Keown’s other argument which suggests that. if autonomy is in fact taken seriously, the SSA indicates everyone would be entitled to assistance in dying, for any reason. Smith first points out that this is not in fact a SSA, but rather an argument from consistency, where points A and Z are substantially the same regarding the relevant criterion,[19] then moves on to point out that judges may also make the mistake of overly focussing on either autonomy or the doctor’s judgement, which seems to be evidenced by the Dutch cases,[20] and finally states that the argument that a second doctor’s opinion is no good as a safeguard because they will be ‘pro-euthanasia’ is a logical fallacy.[21] They are simply a doctor who accepts it may be appropriate in some cases. They will still have to make a balanced decision. It is facile and insulting to say that all second opinions will come from doctors who think euthanasia is a brilliant idea for everyone or who mindlessly follow the first doctor’s decision.

The Self-Contradictory Slippery Slope

Perhaps the hardest blow dealt to the SSA is David Enoch’s suggestion that SSAs as argumentative devices inherently do no stand up to scrutiny in the first place.[22] He cleverly constructs a SSA against the use of SSAs using the same (il)logical steps employed by the SSAs against assisted dying or euthanasia to point out the dangers of relying on such arguments when dealing with important legal and moral questions. He argues that SSAs take advantage of our being less than perfect at making and following distinctions once we embark on a certain course of action.

“Being less than perfect at making the second-order distinction between distinctions we’re good at abiding by and those we’re bad at abiding by, we’re bound to fail to make the distinction between good and bad SSAs.”[23]

The conclusion of his meta-SSA is that we therefore should refrain from using any SSAs at all, even good ones.[24] To explain the very real ‘bad consequence’ of using SSAs he suggests that if the SSA against voluntary euthanasia is in fact a bad one (because we are actually good at distinguishing between voluntary and involuntary euthanasia) then failing to notice that this is a bad argument (because acceptance of SSAs in general allows these bad arguments to be taken seriously) could lead to the continued suffering and humiliation of those wishing to die with some dignity and control over the end of their life.[25]

Enoch states that all SSAs rely on the ‘essential premise’ that we are bad at making these distinctions between what should or shouldn’t be an acceptable development towards point ‘Z’ once we allow ‘A’. Suggesting that ‘we’ are bad at making distinctions is quite patronising and quite a serious assertion, even if it can be quite clearly evidenced in certain cases. It also contradicts the SSA supporter’s challenge to Enoch’s meta-SSA against the use of such arguments. The SSA supporter must show that the ‘we’ they are talking about are worse at making distinctions between types of euthanasia or assisted dying than ‘we’ are at making distinctions between good and bad SSAs.[26] This seems unlikely; people would generally be better at making a distinction between issues regarding the ending of a life than of which arguments are sound. People are notoriously bad at filtering logical fallacies, yet hold fairly definite views on matters of life and death.

Neither myself nor Enoch preach strictly against the use of such arguments in all casesl,[27] but rather that reliance on SSAs can be more dangerous than other forms of justification.[28] First of all, we, as semi-reasonable debators, tend to be somewhat better at evaluating other forms of argument; but more significantly, the consequences are less dire for accepting a bad non-SSA argument. If someone accepts a bad argument, they are wrong, but the argument may be disproven. If someone accepts a bad SSA they are wrong but it may be very hard to change their mind – even proving them ‘wrong’ may not be enough. Proving the SSA wrong, they may think you are merely saying that A is not morally wrong, when you are in fact arguing against their reasoning for not allowing A in the first place (as it may lead to Z). If they sense they are wrong, they may cling to the ‘necessity’ of not even making the first step down the slippery slope.

Not to say that SSAs are the only reason not to make a move towards some form of euthanasia, but for the purpose of my current argument it sheds some light on the suggestion that SSAs should not be the strong determining factor that they seem to be in these cases. If judges want to take a stand they should not hide behind persuasive sounding logical fallacies that say little and run the risk of sacrificing the individual to the greater good.[29] The question is whether or not the courts in Britain and elsewhere have relied too heavily on such arguments. The evidence seems to indicate that they have. Most of the major cases and debates connected to this issue raise the worries about ‘slippery slopes’,[30] that the ‘floodgates’ will open,[31] that the vulnerable in society must be protected,[32] or that this sets a dangerous precedent or might be ‘crossing the Rubicon’;

“So to act is to cross the Rubicon which runs between on the one hand the care of the living patient and on the other hand euthanasia – actively causing his death to avoid or to end his suffering. Euthanasia is not lawful at common law.”[33]

~ Shane

Photo Credit: Paul Graham Raven via photopin cc


[1] A and Z are being used here rather than the perhaps more traditional A and B. David Enoch uses the A and Z formula to better illustrate the large number of possible intermediary positions (B-Y) between the two positions being discussed. D Enoch ‘Once You Start Using Slippery Slope Arguments You’re On a Very Slippery Slope’ (2001), Oxford Journal of Legal Studies 21(4), 629-647.

[2] Ibid, at 629.

[3]A Trimble, ‘America’s Slippery Slope Has Become a Cliff’ 23 Dec 2012, and ‘Think We’re Not Sliding Down A Slippery Slope?’ 22 Aug 2012, Unreported World News available at

[4] “Take away assault weapons, and it’s a slippery slope to taking away all guns. And so it goes. Guns don’t kill, people do. Every family needs a gun to protect itself from home invasion. A majority of Americans don’t buy into these arguments, but they silently acquiesce to them.” from D Chopra, ‘Gun Control Is About the Silent Majority’ 24 Dec 2012, Huffington Post Politics Blog, available at  as well as H Abdullah and A Brennan ‘Gun owners fear new legislation could tread on their rights’ 21 Dec 2012, CNN Election Center, available at

[5] R Smith ‘Euthanasia: Time for a Royal Commission’ (1992) BMJ, Vol 305,  728.

[6] For a clear illustration of the euthanasia and assisted dying spectrum broken down based on voluntariness and the active/passive distinction see J K Mason and G T Laurie, Mason and McCall Smith’s Law and Medical Ethics, (2011), 8th Edition, Oxford, Oxford University Press, at fig 18.1.

[7] As Phillipa Foot points out they would have to accept that “There could be acts of voluntary euthanasia both active and passive against which neither justice nor charity would speak”. See P Foot ‘Euthanasia’ in Virtues and vices and other essays in moral philosophy, (1978), Oxford, Basil Blackwell.

[8] Apologies for confirming that Godwin’s Law applies to Medical Jurisprudence papers, but Reductio ad Hitlerum argumentation about Nazi euthanasia programs does unfortunately crop up quite regularly in this debate. See J Rachels, The End of Life, (1996), Oxford, Oxford University Press, at 175–178.

[9] J Keown, Euthanasia, Ethics and Public Policy: An Argument Against Legalisation, (2002),Cambridge University Press.

[10] S W Smith ‘Fallacies of the Logical Slippery Slope in the Debate on Physician-Assisted Suicide and Euthanasia’ Summer 2005, Medical Law Review, 13(2), 224-243

[11] S W Smith ‘Evidence for the Practical Slippery Slope in the Debate on Physician Assisted Suicide and Euthanasia’ Spring 2005, Medical Law Review, 13, 17–44 at 24..

[12] Ibid

[13] Ibid at 25, citing Willems et al ‘Attitudes and Practices Concerning the End of Life’ (2000), 160 Archives of Internal Medicine, 63–68.

[14] Ibid at 27.

[15] Ibid 36-39.

[16] n 9 above at 77.

[17] D Price ‘What shape to euthanasia after Bland? Historical, contemporary and futuristic paradigms’ (2009), 125 LQR (Jan), 142-174 at 165, citing H Lillehammer ‘Voluntary Euthanasia and the Logical Slippery Slope Argument'(2002), CLJ 545.

[18] n 10 above at 233

[19] Ibid at 230

[20] Ibid at 237

[21] Ibid  at 242.

[22] n 1 above.

[23] Ibid at 629.

[24] Ibid at 635.

[25] Ibid at 636.

[26] Ibid at 640.

[27] It would certainly be something of a disadvantage to those in the legal profession.

[28] n 1 above at 641-642

[29] While fears about regulation are tied to the SSA, a more reasoned approach to dealing with these fears might be to address them head on by analysing the possible methods of regulation rather than simply dismissing the idea outright. “[…] while we might sympathise with each individual who is suffering and requests to die, can we be sure of establishing a regulatory framework that will respect their wishes while protecting the interests of those who have not, and cannot, express any such wish?”, see G Laurie ‘Physician Assisted Suicide in Europe: Some Lessons and Trends’ (Editorial, 2005), 12 European Journal of Health Law, 5–8.

[30] R (Pretty) v Director of Public Prosecutions (Secretary of State for the Home Department intervening) [2002] 1 A.C. 800, para 54.

[31] LIFE ‘An attempt to open the floodgates to euthanasia: the case of Tony Nicklinson’, available at

[32] n 30 above para 96-97 with similar comments made in the ECtHR case, see Pretty v United Kingdom (2346/02), (2002) 35 EHRR 1, paras 74 and 89.

[33] In the Bland case, Airedale NHS Trust v Bland [1993] AC 789, Lord Goff’s comments at 865. Relied heavily upon in In Re A (Children) (Conjoined Twins: Surgical Separation) [2001] Fam 147.



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s