What is the "inference principle" of causation?

With respect to the "inference principle" of causation described by Lambert J.A. in Haag v. Marshall, supra, I would respectfully adopt the reasoning of Smith J.A. in B.M. v. British Columbia (Attorney General) (2004) 31 B.C.L.R. (4th) 61, 2004 BCCA 402 at para. 153, to the effect that it is "restricted to rare cases where it is clear that the defendant(s) controlled all possible physical agents of harm and it is impossible to identify scientifically the pathogenesis of the harm and, therefore, to attribute precise responsibility for the harm as between the tortious acts of several defendants or as between one defendant’s tortious and non-tortious acts." These circumstances do not arise in this case for several reasons, including the fact no tortious act — a failure to take reasonable care — was proven.