What is the effect of the old rule of probable cause on contributory negligence?

Moreover, the ensuing discussion runs only to that portion of the old rule which turned upon the issue of proximate cause and held that the consumption rather than the furnishing of the liquor was the proximate cause of injury. Vesely points out that one whose negligence 'is a substantial factor in causing injury, * * * is not relieved of liability because of the intervening act of third person (the drinker) if such act was reasonably foreseeable at the time of his negligent conduct.' (p. 163, 95 Cal.Rptr. p. 630, 486 P.2d p. 158.) Thus the seller's negligent act remains an actionable proximate cause, even though the drinker's consumption is a contributing cause. The Vesely discussion emphasizes that there may be more than one actionable cause of an injury, and it follows that not every intervening act breaks the chain of causation as to an injured third party. But application of this rule of probable cause does not sustain the right of the injured drinker himself to recover. Rather, if the concurrent negligence of the plaintiff is a proximate contributing cause of his injury, his own recovery is barred by his contributory negligence. It is clear that contributory negligence of the decedent bars recovery by his heirs (Buckley v. Chadwick, 45 Cal.2d 183, 194--201, 288 P.2d 12, 289 P.2d 242).