Beldycki Estate v. Jaipargas, 2012 ONCA 537 has a helpful analysis of how courts approach compensation for future contingent events:
 Courts deal with alleged past events and potential future or hypothetical events in different ways.
 Past events must be proven on the evidence adduced at trial by the party who bears the onus of proof. Once proven to the applicable standard of proof, we treat those past events as certainties: Athey, at para. 28. In an action for negligence, the court must decide whether the defendant was negligent and whether the defendant’s negligence caused the plaintiff’s injury. Once proven, negligence and causation are accepted as certainties: Athey, at para. 28.
 On the other hand, hypothetical or future events, such as how the plaintiff’s life would have proceeded without the failed diagnosis, need not be proven, but simply accorded weight on the basis of their relative likelihood. A future or hypothetical possibility will be taken into account provided it is a real and substantial possibility and not mere speculation: Athey, at paras. 27 and 41.
 A trier of fact required to assess future pecuniary loss becomes engaged in an exercise that is, perforce, somewhat speculative. The ultimate questions to be decided cannot be proved or disproved in the same way as facts relating to past events. A plaintiff who seeks compensation for future pecuniary loss need not prove on a balance of probabilities a loss or diminution of future earning capacity or a requirement of future care because of a defendant’s wrong. A plaintiff who establishes a real and substantial risk of future pecuniary loss is entitled to compensation: Graham v. Rourke (1990), 75 O.R. (2d) 622 (
 However, a plaintiff who establishes a real and substantial risk of future pecuniary loss is not necessarily entitled to the full measure of that potential loss. Entitlement to compensation depends, in part at least, on the degree of risk established. Risk in this sense refers to the risk of future loss – not the degree to which causation was established. The measure of compensation will also depend on the possibility, if any, that a plaintiff would have suffered some or all of the projected losses even if the wrong done to him or her had not occurred: Graham, at pp. 634-635.
 A contingency is a chance occurrence, something that is dependent on an uncertain event. We refer to factors that affect the degree of risk of future economic loss and the possibility that all or part of these losses may have occurred apart from the tortious conduct that underpins the litigation as contingencies: Graham, at p. 635.
 As a general rule, we take account of contingencies that might affect future earnings. This is so despite the fact that these contingencies are already implicitly contained in an assessment of the projected average level of earnings of the person wronged. Not all contingencies are adverse. And some public and private schemes cushion individuals against adverse contingencies. The percentage deduction is generally small: Andrews v. Grand & Toy Alberta Ltd.,  2 S.C.R. 229, at p. 253.
 Contingencies may be general or specific. General contingencies represent the common lot of all of us. Adjustments based on general contingencies should only be modest: Graham, at p. 636. Specific contingencies are peculiar to an individual plaintiff and require evidentiary support for the conclusion that the occurrence of the contingency is a realistic, not merely a speculative possibility: Graham, at p. 636; and Schurrip v. Koot (1977), 18 O.R. (2d) 337 (