
527 P.2d 252 (1974)
Ralph E. CARLSON, Respondent,
v.
The MAY DEPARTMENT STORES COMPANY, Doing Business As Meier & Frank Co., Appellant.
Supreme Court of Oregon.
Argued and Submitted October 8, 1974.
Decided October 24, 1974.
Richard A. Roseta, Eugene, argued the cause for appellant. On the briefs were William G. Wheatley and John E. Jaqua, Eugene.
Darst B. Atherly, Eugene, argued the cause and filed a brief for respondent.
Before O'CONNELL, C.J., and McALLISTER, TONGUE, HOWELL, SLOPER and LEAVY, JJ.
SLOPER, Justice Pro Tem.
This is an action for personal injuries brought by plaintiff for an injury to his right foot allegedly occurring while trying on a pair of shoes in defendant's store. Trial was had before the court upon a waiver of a jury and defendant appeals from a judgment in favor of plaintiff.
Defendant's sole assignment of error is that plaintiff's proof and the court's findings are legally insufficient to support the judgment. Under our previous decisions, the scope of our review in this case is limited to a determination of whether the trial judge's decision is supported by any competent substantial evidence. It is not our function to pass on the credibility of witnesses or to weigh the evidence, and on appeal we must view the evidence in the light most favorable to plaintiff. See Sexton v. Kelly, 185 Or. 1, 12, 200 P.2d 950 (1948); Cronn v. Fisher, 245 Or. 407, 416, 422 P.2d 276 (1966); Anaheim Co. v. Holcombe, 246 Or. 541, 548, 426 P.2d 743 (1967); and Boyce v. Standard Investment Co., 263 Or. 82, 84, 501 P.2d 65 (1972). We must, therefore, examine the evidence to determine its sufficiency, to withstand defendant's attack, by the standards previously referred to.
Plaintiff, in company with his wife and son, visited defendant's store to purchase a pair of shoes for the son. While plaintiff's son was being fitted for a pair of shoes, plaintiff discovered a pair of shoes that he wished to try on. Plaintiff and his wife seated themselves and asked the clerk for a shoe in plaintiff's size. The clerk returned with several pairs of shoes and proceeded to put one on plaintiff's right foot. The clerk had been working in the shoe store for about one month. As the *253 shoe clerk was attempting to assist plaintiff in putting plaintiff's right foot into the shoe, plaintiff experienced intense pain, jumped up out of the chair in which he had been sitting and exclaimed, "You really got me," and then the clerk asked if he should help put on the other shoe and plaintiff declined and said, "Oh, no. I'll put the other one on myself." The clerk when using a shoehorn used a metal shoehorn with a lip at the top and testified that the lip hooks over the forefinger of the right hand and that the bottom of the shoehorn rests loosely in the shoe and that the shoehorn is not otherwise guided or braced. The clerk has no recollection of the incident described by plaintiff, although he acknowledges that he, in fact, sold the shoes in question to plaintiff. The shoes were of a soft suede type. Until the occurrence described by plaintiff on March 15, 1971, plaintiff had been a physically active person and had no prior pain or difficulty with his right heel. Since the time of the occurrence plaintiff has experienced pain in his right heel of a sufficient severity that he has been forced to curtail to a substantial degree his normal activities. Three associates of plaintiff, including his orthopedic surgeon, corroborated his continuing difficulties, having on various occasions personally observed outward manifestations of physical pain associated with his right heel. Plaintiff's medical expert diagnosed plaintiff's condition to be one of chronic degenerative tendonitis with calcification and testified that in his opinion and to a reasonable medical certainty the injury was caused by the incident with the shoehorn and that it is probable that in the future plaintiff's condition will require corrective surgery.
While there was no eyewitness testimony of the precise manner of the manipulation of the shoehorn by the clerk, plaintiff using his sense of feel could certainly feel the shoehorn as it came into contact with his foot. It is well settled that negligence and causation may be proven by circumstantial evidence. Ehler v. Portland Gas & Coke Co., 223 Or. 28, 38, 352 P.2d 1102, 1106, 353 P.2d 864 (1960). This rule, however, is subject to certain limitations; one limitation being that the evidence must be such that there is a rational basis for concluding that it was more probable than not that defendant's negligence caused plaintiff's injury. Kaufman v. Fisher, 230 Or. 626, 636, 371 P.2d 948 (1962). It is not necessary for plaintiff to eliminate all other possible causes of plaintiff's injuries to make a jury question. Eitel v. Times, Inc., 221 Or. 585, 596, 352 P.2d 485, 5 A.L.R.3d 86 (1960). Professor Prosser, who is quoted in several of our decisions, expresses the proposition as follows:
"* * * What is required is evidence from which reasonable men may conclude that, upon the whole, it is more likely that there was negligence than that there was not. Where the conclusion is a matter of mere speculation or conjecture, or where the probabilities are at best evenly balanced between negligence and its absence, it becomes the duty of the court to direct the jury that the burden of proof has not been sustained." Prosser, Torts (2d ed.) 200, § 42.
Our most careful examination and consideration of the evidence before us and of the prior decisions of this court, convinces us that plaintiff's evidence was sufficient to permit the trial judge to find that it was more probable than not that defendant's negligence was the cause of plaintiff's injury.
The case is affirmed.
