The difference between and inference and a hunch

Jacques Home Town Dry Cleaners v. Nova Scotia (Attorney General) 2013 NSCA 4 deals with the difference between an inference and a hunch, and the importance of properly drawn inferences in the context of judicial decision-making.  The Court writes:

[31]        An inference may be described as a conclusion that is logical.  An inference is not a hunch.  A hunch is little more than a guess, a 50/50 chance at best, that may turn out to be right or wrong, once all the facts are brought to light.  Whereas an inference is a conclusion reached when the probability of its likelihood is confirmed by surrounding, established facts.  When engaged in the process of reasoning we are often called upon to draw an inference which acts as a kind of cognitive tool or buckle used to cinch together two potentially related, but still separated propositions.  In the context of judicial decision-making, drawing an inference is the intellectual process by which we assimilate and test the evidence in order to satisfy ourselves that the link between the two propositions is strong enough to establish the probability of the ultimate conclusion.  We do that based on our powers of observation, life's experience and common sense.  In matters such as this, reasonableness is the gauge by which we evaluate the strength of the conclusion reached through our reasoning.

[32]        Two examples will illustrate my point.  We anticipate it being more likely than not, that a wild toss of the football towards the sideline by a fleeing, desperate quarterback will land out of bounds.  We know where the sidelines are, we see the errant throw sail off in that direction, and we can be sure the pass will be whistled out of bounds without needing to see the proof on instant replay.  Similarly, noticing puddles on the street, and then a wet umbrella by the door tells us that it was raining, without having been outside in the rain to witness it.

[33]        When it comes to reviewing inferences on appeal we apply the same "palpable and overriding error" standard of review to inferences, as we do to facts found to exist by direct evidence.  See for example, Housen v. Nikolaisen,2002 SCC 33 (CanLII), 2002 SCC 33; H.L. v. Canada (Attorney General),2005 SCC 25 (CanLII), 2005 SCC 25; and McPhee v. Gwynne-Timothy,2005 NSCA 80 (CanLII), 2005 NSCA 80 where this Court said at ¶31-32:

[31]     A trial judge's findings of fact are not to be disturbed unless it can be shown that they are the result of some palpable and overriding error. The standard of review applicable to inferences drawn from fact is no less and no different than the standard applied to the trial judge's findings of fact. Again, such inferences are immutable unless shown to be the result of palpable and overriding error. If there is no such error in establishing the facts upon which the trial judge relies in drawing the inference, then it is only when palpable and overriding error can be shown in the inference drawing process itself that an appellate court is entitled to intervene. Thus, we are to apply the same standard of review in assessing Justice Richard's findings of fact, and the inferences he drew from those facts. [Cases omitted]

[32]     An error is said to be palpable if it is clear or obvious. An error is overriding if, in the context of the whole case, it is so serious as to be determinative when assessing the balance of probabilities with respect to that particular factual issue. Thus, invoking the "palpable and overriding error" standard recognizes that a high degree of deference is paid on appeal to findings of fact at trial. See, for example,Housen, supra, at para. 1-5 and Delgamuukw v. British Columbia,1997 CanLII 302 (SCC), [1997] 3 S.C.R. 1010 at paras. 78 and 80. Not every misapprehension of the evidence or every error of fact by the trial judge will justify appellate intervention. The error must not only be plainly seen, but "overriding and determinative."

[34]        Inferences, like findings of fact, will not be disturbed unless they fall outside a spectrum or range of reasonableness.  Such restraint and deference was explained by Professor Adrian A.S. Zuckerman in his text Civil Procedure  (London: LexisNexis U.K., 2003) cited with approval by the Court in H.L., supra, where the author stated:

...if the appeal court cannot conclude that the lower court's inference from the primary facts was wrong, in the sense that it fell outside the range of inferences that a reasonable court could make, the appeal court should allow the lower court's decision to stand ... Put another way, as long as the lower court's conclusions represent a reasonable inference from the facts, the appeal court must not interfere with its decision.

[35]        My colleague Justice Fichaud put it nicely in Johansson v. General Motors of Canada Ltd., 2012 NSCA 120 (CanLII), 2012 NSCA 120 where in the context of a non-suit motion brought in a civil jury trial he said:

[81]      ... An inference is a finding deduced or induced from a premise without direct evidence of the inferred fact. It is a factual jump on the reasoning path. The judge ensures that the span is not so broad or irrational that a reasonable jury would stumble. Otherwise the system trusts the jury's common sense and agility to mind the gap and land softly. ...