What would have happened in both the past and the future had it not been for the accident?

The determination of what would have happened in both the past and the future had it not been for the accident, and the determination of what will happen in the future given the accident did occur, are hypothetical exercises. While actual past events must be proven on a balance of probabilities, the standard of proof in relation to hypothetical events is simple probability: Athey at para. 27. If a plaintiff establishes a real and substantial possibility, as opposed to a speculative possibility, of a hypothetical event, the event must be given weight according to its relative likelihood and compensation must be awarded based on an estimation of the chance that the event will occur: Steward v. Berezan, 2007 BCCA 150 at para. 17. The court must make allowances for the possibility that the assumptions upon which the determination is based may prove to be wrong, and all contingencies, positive and negative, that are established as realistic as opposed to speculative possibilities must be given effect.

In the result, to award damages for loss of past earning capacity, the court must be satisfied, on a balance of probabilities, that the accident caused an impairment of the plaintiff's ability to engage in some activity relevant to his income earning potential and, if so satisfied, the court must assess the chances that the plaintiff would have earned more income than he did earn in the pre-trial period had he not been injured and make an award based on that assessment that reflects all realistic contingencies: Smith v. Knudsen, 2004 BCCA 613 at paras. 31, 36-37.