Reductio ad absurdum is

A method of proof which proceeds by stating a proposition and then showing that it results in a contradiction, thus demonstrating the proposition to be false.

See Wolfram MathWorld:
<http://mathworld.wolfram.com/ReductioadAbsurdum.html>

The validity of this method of refuting a proposition was acknowledged by the Supreme Court of Canada as early as 1914 and as recently as 2000. See Townsend v. Northern Crown Bank, 49 SCR 394 at 397-98 (“That is almost a reductio ad absurdum, and Mr. Laidlaw, of course, did not assume any such untenable position, rather he tried to escape for it.”)  and R. v. Proulx, 2000 SCC 5 at para. 53, [2000] 1 SCR 61 (used to describe an analysis leading to a “penalogical paradox”).

A CanLII search done on August 23, 2012  has the earliest reported use on its database in a 1887 Ontario Court of Appeal decision and the most recent early in 2012. One of the cases produced by that search is R. v. Renouf, 2001 NFCA 56, 160 CCC (3d) 173 where, at para. 16, the Newfoundland & Labrador Court of Appeal quoted from one its 1999 decisions: “”On their face, the above results appear to defy common sense. However, the law is replete with possibilities of “reductio ad absurdum” situations which in reality do not occur regularly and, indeed, can usually be avoided by the exercise of a modicum of care.”

But then, of course, sometimes these situations do occur regularly in law and cannot be avoided even by the exercise of the utmost care (at least by a judge).

The proposition is that the material contribution doctrine as explained by the Supreme Court of Canada in Clements v. Clements, 2012 SCC 32 is incoherent.

What you’re about to read is:

(1)  an explanation that shows why the material contribution doctrine, as described in Clements v. Clements, 2012 SCC 32, amounts to a restatement of the existing indivisible injury doctrine when applied to claims that involve multiple  tortious causes with multiple wrongdoers where the evidence is that each of those causes, by itself, would have been a but-for cause of at least some of the injury and losses alleged by plaintiff;

(2)  an explanation of why one of the two categories of situation that fall within the Clements “bright line” statement of when material contribution to risk applies – the application of the doctrine premised on the assumption that plaintiff cannot validly establish factual causation on the balance of probability so but should be allowed to prove causation regardless – is a situation where the plaintiff has established factual causation on the balance of probability against at least two or more of the tortfeasors.

Reduction ad absurdum.

So, pull up  chair, grab a tipple, and let’s begin.

We now know that the indivisible injury doctrine (as explained in Athey v. Leonati [1996] 3 SCR 458, 1996 CanLII 83) must be understood to be premised on the assumption that each of the tortious causes could be a but-for cause, on its own, of the indivisible injury but the existence of the multiple tortious causes, each of which could be a but-for cause on its own, prevents the court from attributing the injury to any one of the causes and not the other(s).

And we have to understand, until we’re told otherwise, that the indivisible injury doctrine is a doctrine of factual causation established on the balance of probability.

And we now know that the Clements version of material contribution applies only to claims that involve multiple tortious causes with multiple wrongdoers where the evidence is that each of those causes, by itself, would have been a but-for cause of at least some of the injury and losses alleged by plaintiff, and the existence of  the multiple tortious causes, each of which could be a but-for cause on its own,  prevents the court from attributing the injury to any one of the causes and not the other(s).

And we also now have to understand, until we are told otherwise, that the Clements material contribution doctrine which also applies only where there are multiple wrongdoers tortious causes is not a doctrine of factual causation established on the balance of probability.

Two doctrines premised on antithetical assumptions applying to the same facts.

Do you consider that a contradiction?

Reductio ad absurdum

For example.

Assume a plaintiff alleges  injury as the result of more than one tortious incident and seeks to hold all of the multiple tortfeasors jointly and severally liable for all of the damages alleged to have been caused by the combined effects of the multiple incidents.

The British Columbia Court of Appeal wrote in Bradley v. Groves, 2010 BCCA 36 at paras. 20-21,  leave to appeal dismissed 2011 CanLII 20960, referring to Athey v. Leonati [1996] 3 SCR 458, 1996 CanLII 83:

[20]     In the course of the discussion, Major J. (for the Court) described injuries produced by more than one cause as either “divisible” or “indivisible”. Divisible injuries are those capable of being separated out and having their damages assessed independently. Indivisible injuries are those that cannot be separated or have liability attributed to the constituent causes. …

[21]     Accordingly, liability to a plaintiff for indivisible injuries is joint and several.

The reference Athey includes para. 25:

[25]     In the present case, there is a single indivisible injury, the disc herniation, so division is neither possible nor appropriate. The disc herniation and its consequences are one injury, and any defendant found to have negligently caused or contributed to the injury will be fully liable for it

So, then, according to Athey, a necessary precondition for the application of the doctrine of indivisible injury is that the defendant’s negligence be found to have been a cause of the indivisible injury.

That, of course, does not answer the question: how is the defendant’s negligence  to be found to have  been a cause, in law, of the indivisible injury?

We now know that, for Canadian negligence law, there are two methods open to a plaintiff: the but-for test and the Clements-Resurfice material contribution test. The Supreme Court wrote in Clements v. Clements, 2012 SCC 32 at para. 46:

[46]     The foregoing discussion leads me to the following conclusions as to the present state of the law in Canada:

(1)      As a general rule, a plaintiff cannot succeed unless she shows as a matter of fact that she would not have suffered the loss “but for” the negligent act or acts of the defendant. A trial judge is to take a robust and pragmatic approach to determining if a plaintiff has established that the defendant’s negligence caused her loss. Scientific proof of causation is not required.

(2)      Exceptionally, a plaintiff may succeed by showing that the defendant’s conduct materially contributed to risk of the plaintiff’s injury, where (a) the plaintiff has established that her loss would not have occurred “but for” the negligence of two or more tortfeasors, each possibly in fact responsible for the loss; and (b) the plaintiff, through no fault of her own, is unable to show that any one of the possible tortfeasors in fact was the necessary or “but for” cause of her injury, because each can point to one another as the possible “but for” cause of the injury, defeating a finding of causation on a balance of probabilities against anyone.

So we know now, from Clements, that the exceptional material contribution doctrine can apply only where there are multiple negligent persons each of whose negligent conduct would be a but-for cause if the negligence of all of the other persons had not occurred and  only where there are no non-tortious events which could be but-for causes.

And, we also know, from Athey, para. 41.1,  that the indivisible injury doctrine applies only where are no non-tortious causes (excluding the contributory negligence of the injured person) which non-tortious cause(s) would be a but-for cause of the negligence did not exist.

[41.1]     If the disc herniation would likely have occurred at the same time, without the injuries sustained in the accident, then causation is not proven.

And we know from Athey that the consequences of the application of the indivisible injury doctrine to any defendant held liable is joint and several liability.

But, as explained in Athey, the reason that the injury is called “indivisible” is that “division” – meaning allocation of the injury to the various causes is “neither possible nor appropriate”.

It wasn’t appropriate in Athey because (as confirmed in Clements) all of the two tortious incidents and the non-tortious exercise where cumulatively necessary causes of the disc herniation. (See Athey para. 41.2 and Clements paras. 22-23)  It also wasn’t possible for that reason.

But, let’s, now, vary the Athey facts. In the first variation, the only causes were the two separate tortious acts each of which would be sufficient but-for causes if the other had not occurred. In the second, we’ll keep the exercise and assume that it, too, would have been a but-for cause even if the accidents had not occurred.

We can easily dispose of the second variation. There is no liability. See Athey para. 41.1 quoted above.

That leaves the first variation: each of the two motor vehicle accidents would have been but-for causes if the other had not occurred.

That makes it the situation described in Clements, para. 46 (2)

That makes it Bradley v. Groves. In Bradley, the plaintiff was injured in two separate motor vehicle accidents each of which was caused by negligence of another person.

(To give you a hint where this is going is: why do we need Clements 46(2) – the Clements version of material contribution if the situation can be described as one of indivisible injury; and if it can, what’s the difference between an indivisible injury situation and one to which Clements material contribution applies?)

So let’s go back to what Bradley said are the consequences of indivisible injury, taking into account Athey and subsequent Supreme Court of Canada decisions.

[22]    The conclusions in Athey were further refined in the decision of the Supreme Court in E.D.G. v. Hammer, 2003 SCC 52 (CanLII), 2003 SCC 52, [2003] 2 S.C.R. 429. Though not dispositive of that appeal, the judgment reinforced the distinction between divisible and indivisible injuries, and the principle that tortfeasors who cause or contribute to a single injury will be held jointly liable. E.D.G. was a case involving a plaintiff who had suffered sexual abuse as a child at the hands of the defendant, Mr. Hammer, who was a janitor at her school. The plaintiff was also sexually abused by a number of other individuals as a child. She sought to recover from, in addition to Mr. Hammer, the School Board which had employed him.

[23]    In E.D.G. the majority of the Court per McLachlin C.J.C., said as follows:

3.  Did the Trial Judge Properly Apportion the Damages Between Mr. Hammer and E.D.G.’s Subsequent Abusers?

[28]    Since I have concluded that the Board is not liable to E.D.G. for any of the damage caused by Mr. Hammer, it is not strictly necessary to consider the issue raised on the Board’s cross-appeal. However, because the Board rests its challenge on the claim that Vickers J. misapplied a principle laid out in Athey v. Leonati,1996 CanLII 183 (SCC), [1996] 3 S.C.R. 458, it will be useful to consider the Board’s challenge.

[29]    The Board’s challenge concerns that portion of the damages that was, in the view of Vickers J., caused jointly by Mr. Hammer and the subsequent abusers. Vickers J. held Mr. Hammer liable for the sum total of these damages, stating that “[a]s long as he [Mr. Hammer] is a part of the cause of the injury, even though his acts alone did not create the entire injury, his responsibility for the [entire] damage that flows from that injury is established” (para. 57). As an authority for this proposition, Vickers J. cited Major J.’s claim in Athey, supra, at para. 17, that “[a]s long as a defendant is part of the cause of an injury, the defendant is liable, even though his act alone was not enough to create the injury”. ([underline] emphasis in original).

[30]    In the Board’s submission, Vickers J. was incorrect in applying this principle to the case at bar. The principle applies, the Board claims, only where the other cause is non-tortious and is a precondition of the injury, not where it is tortious and occurs subsequently.

[31]    In my view, the Board’s reading of the principle articulated in Athey is overly narrow. After making the claim cited above, Major J. further expanded upon his reasoning, stating at para. 19 that:

The law does not excuse a defendant from liability merely because other causal factors for which he is not responsible also helped produce the harm …. It is sufficient if the defendant’s negligence was a cause of the harm…. [First emphasis added; second emphasis in original.]

(This principle is not confined to cases involving non-tortious preconditions. It applies to any case in which the injuries caused by a number of factors are indivisible. DC

Back to  Bradley v. Groves.

[32]    The matter is governed by the Negligence Act, R.S.B.C. 1996, c. 333, s. 4, which provides that “[i]f damage or loss has been caused by the fault of 2 or more persons”, then “(a) they are jointly and severally liable to the person suffering the damage or loss”. This rule implies that Mr. Hammer is liable to E.D.G. for the full cost of any injuries that are indivisible and caused both by Mr. Hammer and by the subsequent tortfeasors.

[Underline emphasis in original; bold emphasis added. DC]

[24]    We take from this that indivisible injuries, whether occasioned by a combination of non-tortious and tortious causes or solely by tortious causes, result in joint liability for tortfeasors. This does not prevent jointly liable parties from seeking contribution and indemnity from each other under the Negligence Act, R.S.B.C. 1996, c. 333.

[25]    This conclusion is supported by the Supreme Court’s comments on apportionment in Blackwater. Blackwater was a case involving an individual who was repeatedly and brutally sexually assaulted at a residential school, for which assaults the defendants, Canada and the United Church of Canada, were found liable. However, the plaintiff was already injured by previous traumas. Although the reasons for judgment dealt primarily with the question of how to address the plaintiff’s pre-existing elevated susceptibility to injury (sometimes referred to as a “thin-skull”) and the likelihood the plaintiff would continue to suffer debilitating effects from other injuries even without additional tortious harm (sometimes referred to as a “crumbling skull”), there is helpful commentary on the effect of a finding of indivisibility (or, conversely, a finding of divisibility). Chief Justice McLachlin, for the Court [in Blackwater v. Plint: DC], stated:

[78]    It is important to distinguish between causation as the source of the loss and the rules of damage assessment in tort. The rules of causation consider generally whether “but for” the defendant’s acts, the plaintiff’s damages would have been incurred on a balance of probabilities. Even though there may be several tortious and non-tortious causes of injury, so long as the defendant’s act is a cause of the plaintiff’s damage, the defendant is fully liable for that damage. The rules of damages then consider what the original position of the plaintiff would have been. The governing principle is that the defendant need not put the plaintiff in a better position than his original position and should not compensate the plaintiff for any damages he would have suffered anyway: Athey. Mr. Barney’s submissions that injury from traumas other than the sexual assault should not be excluded amount to the contention that once a tortious act has been found to be a material cause of injury, the defendant becomes liable for all damages complained of after, whether or not the defendant was responsible for those damages.

…

[35]     This is not a case of this Court overturning itself, because aspects of Long v. Thiessen were necessarily overruled by the Supreme Court of Canada’s decisions in Athey, E.D.G., and Blackwater. Other courts have also come to this same conclusion: see Misko v. Doe, 2007 ONCA 660 (CanLII), 2007 ONCA 660, 286 D.L.R. (4th) 304 at para. 17.

[36]     It may be that this represents an extension of pecuniary liability for consecutive or concurrent tortfeasors who contribute to an indivisible injury. We do not think it can be said that the Supreme Court of Canada was unmindful of that consequence. Moreover, apportionment legislation can potentially remedy injustice to defendants by letting them claim contribution and indemnity as against one another.

[37]    We are also unable to accept the appellant’s submission that “aggravation” and “indivisibility” are qualitatively different, and require different legal approaches. If a trial judge finds on the facts of a particular case that subsequent tortious action has merged with prior tortious action to create an injury that is not attributable to one particular tortfeasor, then a finding of indivisibility is inevitable. That one tort made worse what another tort created does not automatically implicate a thin or crumbling skull approach (as in Blackwater), if the injuries cannot be distinguished from one another on the facts. Those doctrines deal with finding the plaintiff’s original position, not with apportioning liability. The first accident remains a cause of the entire indivisible injury suffered by the plaintiff under the “but for” approach to causation endorsed by the Supreme Court of Canada in Resurfice Corp. v. Hanke, 2007 SCC 7 (CanLII), 2007 SCC 7, [2007] 1 S.C.R. 333. As noted by McLachlin C.J.C. in that case, showing that there are multiple causes for an injury will not excuse any particular tortfeasor found to have caused an injury on a “but-for” test, as “there is more than one potential cause in virtually all litigated cases of negligence” (at para. 19). It may be that in some cases, earlier injury and later injury to the same region of the body are divisible. While it will lie for the trial judge to decide in the circumstances of each case, it is difficult to see how the worsening of a single injury could be divided up.

I’m going to repeat two of the statements  in Bradley:

 [24]    We take from this that indivisible injuries, … occasioned by a combination of …. tortious causes, result in joint liability for tortfeasors.

[37]    … If a trial judge finds on the facts of a particular case that subsequent tortious action has merged with prior tortious action to create an injury that is not attributable to one particular tortfeasor, then a finding of indivisibility is inevitable. …

The emphasis is mine.

But we already know that we don’t need the indivisible injury doctrine  if can say, on the balance of probability, that all of the tortious causes were necessary for the injury.

So we only need the indivisible injury doctrine when we can’t say that, on the balance of probability that any of the tortious causes is a but-for cause (for reasons other than the lack of evidence even if it was the only cause). And, of course, we can’t say that when each of the tortious causes are, themselves, capable of being a but-tor cause.

In which case, when we apply the indivisible injury doctrine, we treat all of the tortious causes as causes-in-fact and this produces joint liability.

But, as we now know, Clements material contribution also applies to this situation, if we take Clements at its word.

In passing (1):  light of Clements,  Athey 41.3 cannot now be understood to permit the use of the Clements version of a material contribution doctrine in instances where the non-tortious act could be a but-for cause. Of course, this is for the Clements material contribution to risk doctrine, which Clements informs us is not a the material contribution to injury doctrine. But, then, according to Clements, it also appears that we no longer have (if we ever did) a material contribution to injury doctrine (test) separate from the but-for test.

In passing (2): in Resurfice, which is the basis for Clements, the Supreme Court stated, at para. 19, ““there is more than one potential cause in virtually all litigated cases of negligence”. The context was the Court’s explanation of why the Alberta Court of Appeal had erred in applying Athey material contribution.

[19]      The Court of Appeal erred in suggesting that, where there is more than one potential cause of an injury, the “material contribution” test must be used. To accept this conclusion is to do away with the “but for” test altogether, given that there is more than one potential cause in virtually all litigated cases of negligence. If the Court of Appeal’s reasons in this regard are endorsed, the only conclusion that could be drawn is that the default test for cause-in-fact is now the material contribution test. This is inconsistent with this Court’s judgments in Snell v. Farrell, 1990 CanLII 70 (SCC), [1990] 2 S.C.R. 311; Athey v. Leonati, at para. 14; Walker Estate v. York Finch General Hospital, 2001 SCC 23 (CanLII), [2001] 1 S.C.R. 647, 2001 SCC 23, at paras. 87-88, and Blackwater v. Plint, 2005 SCC 58 (CanLII), [2005] 3 S.C.R. 3, 2005 SCC 58, at para. 78.

But, if it is the case that “there is more than one potential cause in virtually all litigated cases of negligence” involving two or more negligent parties, at least so long as the case is not one where the negligence of all is cumulatively necessary, then the instances of multiple tortfeasors to which  Clements material contribution applies aren’t exceptional at all. If that is so, then, paraphrasing Resurfice “[t]o accept this conclusion is to do away with the “but for” test altogether [in such instances], given that there is more than one potential cause in virtually all [such] litigated cases of negligence.” [Words in brackets added].

Or, more to the point, in every case  involving multiple negligent parties where it is the case that the negligent conduct of each could be a but-for cause.

But that argument is made, and will continue to be made,  in most litigated cases where there are multiple tortious incidents.

So if one were to suggest that one consequence of Clements will be less need for judges to deal with the meaning of material contribution, that suggestion is demonstrably false if Clements is taken at its word. Of course, if we assume judges will ignore the ordinary grammatical meaning of the text of Clements, for what they believe the Court intended to say, because the judges conclude the grammatical meaning is … problematic? … then we won’t have the problem of the apparent meaning of Clements. We might have pecking order problems, but that’s a different issue.

I’ve shown, in a posting now on Slaw – http://www.slaw.ca/2012/09/15/k-k-k-k-k-katmandu/ – that, if we take para 46(2) of Clements at its word, the material contribution doctrine applies to every instance of negligent double omissions other than those which are cumulatively necessary. If they are cumulatively necessary then the finger-pointing shtick never occurs, because everybody’s negligence is necessary.

Reductio ad absurdum

In passing (3):

But the Supreme Court created both doctrines?

Do they produce the same result? The indivisible injury doctrine produces joint and several liability.

We haven’t yet been told what Clements material contribution produces.

If it produces joint and several liability? Then why do the Clements version of  material contribution at all?

Can you think of an example which won’t trigger both doctrines?

What material contribution doesn’t produce joint and several liability?

Reductio ad absurdum.

In passing (4):

Recall Clements‘ summary, in para. 46(2) of when the material contribution doctrine applies:

(2) Exceptionally, a plaintiff may succeed by showing that the defendant’s conduct materially contributed to risk of the plaintiff’s injury, where (a) the plaintiff has established that her loss would not have occurred “but for” the negligence of two or more tortfeasors, each possibly in fact responsible for the loss; and (b) the plaintiff, through no fault of her own, is unable to show that any one of the possible tortfeasors in fact was the necessary or “but for” cause of her injury, because each can point to one another as the possible “but for” cause of the injury, defeating a finding of causation on a balance of probabilities against anyone.

The examples of the situations that satisfy this description fall into one of two categories: (1) the evidence is not enough for the judge or jury to decide which of the two or more negligent persons is responsible for the negligence which was the but-for cause – as was the case in Cook v. Lewis, , [1951] SCR 830, 1951 CanLII 26; or, (2) there’s evidence to allow the judge or judge to identify the negligence two or more of tortfeasors as but-for causes, so long as one ignores the traditional rule that there can’t be multiple sufficient but-for causes, because, none of the causes can be necessary if each one can be a but-for cause if the other had not occurred.  That is, each tortfeasor’s negligence would be a valid but-for cause if the other tortfeasors’ negligence had not occurred.

in the second category, the approach used by the judge or jury to decide that each of the negligent acts would be a factual cause is a sufficient condition test.  It shows that each of the negligent acts is a factual cause on the balance of probability.

But if it shows that, why is the material contribution to risk doctrine being applied, which is based on the premise that factual causation can’t be proven on the balance of probability?

Reductio ad absurdum.