This appeal is concerned with the propriety of instructing the jury with regard to the following presumption:
“B. The requisite knowledge or belief that property has been stolen is presumed in the case of an individual or dealer who:
“(1) is found in possession or control of property stolen from two  or more persons on separate occasions * * * ” Section 40A-16-11(B), N.M.S.A.1953 (2d Repl.Vol. 6, 1972).
Defendant was convicted of receiving stolen property contrary to § 40A-16-11, N.M.S.A.1953 (2d Repl.Vol. 6, 1972). The trial court instructed the jury pursuant to § 40A-16-11 (B), supra. Defendant now appeals contending that the giving of the instruction in the manner in which it was given and under the evidence adduced at trial was error. We affirm.
Defendant’s two-fold attack on his conviction is based on the trial court’s instruction Nos. 11 and 6 which read as follows:
“11. You are further instructed that the requisite knowledge or belief that the property has been stolen is presumed in the case of an individual who is found in possession or control of property stolen from two or more persons on separate occasions.”
“6 * * *
“A presumption is a conclusion which the law requires the jury to make from particular facts, in the absence of convincing evidence to the contrary. A presumption continues in effect until overcome or outweighed by evidence to the contrary; but unless so outweighed the jury is bound to find in accordance with the presumption.”
Defendant’s initial attack on these instructions is that they fail to comply with Rule of Evidence 303, § 20-4-303, N.M.S.A. 1953 (Repl.Vol. 4, 1970, Supp.1973), and that such failure is violative of his constitutional right to due process of law. Defendant, for purposes of this portion of his argument, makes no contention that the presumption itself is unconstitutional. He argues only that the instructions in the instant case giving mandatory effect to the presumption violates R.Evid. 303(c), supra, which directs the trial court to instruct the jury that it may, but is not required, to find the presumed fact if it finds the existence of the basic facts. Thus, this portion of defendant’s argument is essentially directed at instruction No. 6. It is further submitted that R.Evid. 303(c), supra, is a codification of the United States Supreme Court’s edict against mandatory presumptions in criminal cases. See Bollenbach v. United States, 326 U.S. 607, 66 S.Ct. 402, 90 L.Ed. 350 (1945).
The instant instructions clearly violate R.Evid. 303(c), supra. R.Evid. 303(c), supra, specifically mandates an instruction that the jury is not required to find the presumed fact simply because there is sufficient evidence of the basic facts. The state argues that instruction No. 6 substantially complied with this mandate in that it told the jury that the presumption could be overcome by evidence to the contrary. The point, however, of R. Evid. 303(c), supra, is that even if there is no evidence to the contrary, the jury should be instructed that it is not bound to find in accordance with the presumption. See Committee Commentary to R.Evid. 303(b) and (c), supra. R.Evid. 303(c), supra, incorporates the constitutional requirement that presumptions not be conclusive in criminal cases even if unrebutted. See Bollenbach v. United States, supra; United States v. Gainey, 380 U.S. 63, 85 S.Ct. 754, 13 L.Ed.2d 658 (1965); Barnes v. United States, 412 U.S. 837, 93 S.Ct. 2357, 37 L.Ed. 2d 380 (1973); Bray v. United States, 113 U.S.App.D.C. 136, 306 F.2d 743 (1962).
In the case at bar, instruction No. 11 told the jury that knowledge is presumed from a certain kind of possession. Instruction No. 6 told the jury that a presumption is a conclusion required to be made unless rebutted, and further that the *113jury was bound by the conclusion unless and until evidence to the contrary outweighed it. These instructions were in direct conflict with Rule 303(c), supra. However, defendant did not object to instruction No. 6. Neither did his objection to instruction No. 11 alert the trial court to the vice of instruction No. 6. See infra. Defendant has waived the error. R.Cr.P. 41, § 41-23-41, N.M.S.A.1953 (2d Repl.Vol. 6, 1972 Supp.1973).
The second prong of defendant’s argument is directed solely at instruction No. 11. Defendant’s objection to this instruction at trial was that “ * * * it is not a proper statement of the law and is not supported by the evidence before the jury.” On appeal defendant contends only that since the evidence did not demonstrate that the defendant possessed both items of property simultaneously, the instructions were unsupported by the evidence. Defendant contends that instructions pursuant to § 40A-16-11(B), supra, may only be given when the evidence shows simultaneous possession of property stolen from two or more persons on separate occasions.
Defendant is incorrect in this assertion. We first note, however, that the record supports defendant’s contention that the evidence did not show simultaneous possession. Police officers recovered a stolen television set from the defendant’s possession in late February of 1974. The set must have been stolen shortly before that time although the owner testified that the theft occurred in March or April. In early March, the police obtained information that the defendant had possessed guns stolen in December of 1973, but had already disposed of them. There is no evidence as to when defendant possessed the guns.
It is important to realize that while the legislature (in § 40A-16-11(B), supra), the Supreme Court (in R.Evid. 303, supra), and we (in this opinion thus far) have referred to the rule contained in § 40A-16-11(B), supra, as creating a presumption, it is more appropriately denominated a “standardized inference.” See generally Me-Cormick on Evidence, §§ 342-346 (2d Ed. 1972). That is to say that a “true” presumption shifts the burden of proof; if proof of the basic facts are introduced into evidence, the presumed fact is also taken to be proved in the absence of evidence to the contrary. If no evidence to the contrary is forthcoming, the court is compelled to direct a verdict against the party now having the burden of producing such evidence. In other words, a “true” presumption is conclusive on the jury in the absence of evidence to the contrary. Territory v. Lucero, 16 N.M. 652, 120 P. 304 (1911). An inference, on the other hand, is nothing more than a permissible deduction from the evidence. Territory v. Lucero, supra.
The effect of R.Evid. 303(c), supra, is to abolish “true” presumptions in criminal cases. This puts the “presumptions” contained in § 40A-16-11 (B), supra, into the category of a mere permissible inference from the evidence provided that the jury is properly instructed under R. Evid. 303(c), supra. This contention is mandated by the constitutional requirements heretofore stated. Thus, the language of § 40A-16-11(B), supra, must be read:
“B. The requisite knowledge or belief that property has been stolen [may be] presumed * *
The question, then, with which we must deal on this appeal is whether it is permissible to infer knowledge that property is stolen from proof of two separate instances of possession of property stolen from two or more persons on different occasions.
It is settled law that evidence of a defendant’s prior possession of other stolen property is admissible to establish the knowledge of a defendant that the property was stolen. State v. Sero, 82 N.M. 17, 474 P.2d 503 (Ct.App.1970). The evidence is admissible because it is permissible to infer knowledge from proof of more than one instance of stolen property. See State v. *114Lindsey, 81 N.M. 173, 464 P.2d 903 (Ct.App.1969). The reason for this admissibility is that there is a rational connection between the facts proved and the ultimate fact inferred. Barnes v. United States, supra. The possession need not be simultaneous possession but the time span between the non-simultaneous possessions must be reasonable. What is reasonable must be decided on a case by case basis. Under the facts of the instant case we hold the time span reasonable. There was a rational connection between the facts proved and the ultimate fact inferred.
Yet the jury was not properly instructed in the case at bar. Thus defendant concludes his argument with the assertion that a mandatory presumption that attributes guilty knowledge to one in non-simultaneous possession of property stolen from two individuals on separate occasions is unconstitutional. As stated previously, no objection was made to the mandatory aspect of the instructions. We therefore view defendant’s final contention as being unreviewable unless it can be said that the error, if any, is fundamental or jurisdictional. State v. Jaramillo, 85 N.M. 19, 508 P.2d 1316 (Ct.App.1973). The doctrine of fundamental error is applicable only if the innocence of the defendant appears indisputable or if the question of his guilt is so doubtful that it would shock the conscience to permit his conviction to stand. State v. Parker, 85 N.M. 80, 509 P.2d 272 (Ct.App.1973). We have reviewed the record and conclude that the instant one is not such a case.
It is true that some constitutional violations may render a court incompetent to convict a defendant. Such jurisdictional errors may be raised for the first time on appeal. State v. Foster, 87 N.M. 155, 530 P.2d 949 (Ct.App.1974). However, in this case, the jury was properly instructed as to all the essential elements of the crime. State v. Gunzelman, 85 N.M. 295, 512 P.2d 55 (1973). The jury was instructed that defendant was presumed to be innocent and that his guilt had to be proved beyond a reasonable doubt. See State v. Harrison, 81 N.M. 623, 471 P.2d 193 (Ct.App.1970). In short, we do not believe that the error alleged with regard to the instructions in the case at bar is such as divests the trial court of jurisdiction.
Oral argument in this case is unnecessary.
Defendant’s conviction is affirmed.
It is so ordered.
WOOD C. J., concurs
LOPEZ, J., dissenting.