Appeal from the Circuit Court of Cook County 00 CR 26997 (03) Honorable Joseph G. Kazmierski, Judge Presiding.
 The opinion of the court was delivered by: Justice McBRIDE
 A jury convicted defendant Floyd Cummings of armed robbery. He was sentenced to natural life imprisonment as a habitual criminal. 720 ILCS 5/33B-1 (West 2000)(Habitual Criminal Act). In this appeal, Cummings first claims that his sentence is unconstitutional because the penalties for the identical offenses of armed robbery and armed violence with a category III weapon are disproportionate. Second, he claims that his natural life sentence is unconstitutionally disproportionate to the nature of the offense, his involvement in the offense, his background and character, and the sentences imposed on his co-defendants. Finally, he claims that the trial court failed to conduct an adequate inquiry into his posttrial pro se claims of ineffective assistance.
 The evidence at trial showed that on October 29, 2000, Yashika Jones, Lee Washington, and Cummings robbed a Subway Sandwich Shop located at 5300 South Kimbark, Chicago (the Subway). Jones was an employee of the Subway at the time. Washington was her boyfriend. The two planned the robbery and invited Cummings to participate.
 At about 10:30 p.m., on October 29, 2000, Jones was working at the Subway. She stepped outside and smoked a cigarette. She spoke with Washington, who was outside with Cummings. When Jones entered the Subway again, she did not lock the employee door. Washington and Cummings entered the Subway through the unlocked employee door. According to Johnny Johnson, the manager on duty at the Subway, Washington carried a baseball bat into the Subway. According to Washington and Jones, it was Cummings who carried the baseball bat. In a statement that he made to an assistant State's Attorney, Cummings claimed that Washington held the baseball bat.
 Inside the Subway, Cummings grabbed Johnson by the collar. Washington and Cummings made Johnson unlock the petty cash boxes. They took the money inside the boxes while Jones removed the money from the register in the front of the Subway. Washington and Cummings wanted more money, but Johnson was not able to open the floor safe.
 Cummings used some duct tape he found in the office to tape Johnson's hands, legs, and eyes. At one point, Johnson heard one of the men smashing the television monitors and videocassette recorder in the office. Johnson felt debris from the destruction falling on him. Washington claimed that Cummings smashed the objects with the baseball bat. Cummings claimed it was Washington who destroyed the objects using the baseball bat.
 Eventually, Washington and Cummings asked Johnson for the keys. One of the men struck Johnson when he said he did not know where the keys were. Cummings claimed that it was Washington who struck Johnson. When Washington and Cummings located the keys, Jones used them to open the door. The three left in Cummings' car with the money. They went to Cummings' house, where they divided the money.
 Cummings and Washington drove back to the Subway, hoping to open the floor safe, but as they approached the Subway, they saw the police. Instead of going inside for the floor safe, they went back to Cummings' house. Washington and Jones left Cummings' house together that night. They were arrested shortly thereafter. Each was in possession of some of the proceeds of the robbery. Washington also had the key to the petty cash boxes. Jones and Washington confessed to their participation in the robbery. They pled guilty to charges of armed robbery. Jones was sentenced to six years' imprisonment. Washington was sentenced to eight years' imprisonment.
 Washington provided information, which allowed the police to locate Cummings. Johnson viewed a lineup and identified Cummings as one of the offenders. Cummings subsequently gave a handwritten statement to an assistant State's Attorney, in which he admitted his participation in the robbery. After hearing all the evidence, which included Cummings' statement, the jury convicted Cummings of armed robbery.
 The trial court held a sentencing hearing. It heard evidence that on September 18, 1984, Cummings was sentenced to a minimum of 5 years' imprisonment and a maximum of 10 years' imprisonment for an armed robbery that occurred in Newaygo City, Michigan. Cummings was discharged from the Michigan Department of Corrections on May 10, 1996. Also, on June 19, 1967, Cummings was convicted and sentenced in Cook County for murder. He was sentenced to 50 to 75 years' imprisonment. Cummings was paroled from the Illinois Department of Corrections on May 16, 1979. The trial court found that based on the evidence of Cummings' prior convictions, it was required to sentence him as a habitual criminal. The court imposed a sentence of natural life imprisonment.
 Cummings claims that his sentence of natural life imprisonment is unconstitutionally disproportionate. He urges us to remand for resentencing. The Illinois Constitution provides that "[a]ll penalties shall be determined both according to the seriousness of the offense and with the objective of restoring the offender to useful citizenship" (Ill. Const. 1970, art. I, §11) and that "[n]o person shall be deprived of life, liberty or property without due process of law nor be denied the equal protection of the laws" (Ill. Const., 1970, art. I, §2). "These constitutional provisions mandate penalties which are proportionate to the offenses." People v. Christy, 139 Ill. 2d 172, 177 (1990).
 Cummings argues that armed robbery and armed violence predicated on robbery committed with a category III weapon are identical offenses that have disproportionate penalties. He points out that armed robbery, for which he was convicted, is a Class X felony, punishable by 6 to 30 years' imprisonment. 720 ILCS 5/18-2(b)(West 2000); 730 ILCS 5/5- 8-1(a)(3) (West 2000). Meanwhile, armed violence predicated on robbery with a category III weapon is Class 2 felony, punishable by three to seven years' imprisonment. 720 ILCS 5/33A-3(b) (West 2000); 730 ILCS 5/5-8-1(a)(5) (West 2000). "A Category III weapon is a bludgeon, black-jack, slungshot, sand-bag, sand-club, metal knuckles, billy, or other dangerous weapon of like character." 720 ILCS 5/33A-1(c)(3) (West 2000). Thus, although he was not charged with or convicted of armed violence, Cummings argues that he should be sentenced to three to seven years' imprisonment for the Class 2 offense of armed violence predicated on robbery with a category III weapon.
 Cummings relies on People v. Christy, 139 Ill. 2d 172 (1990), and People v. Lewis, 175 Ill. 2d 412 (1996). In Christy, the defendant was convicted of armed violence predicated on kidnapping with a category I weapon and one count of kidnapping. Christy, 139 Ill. 2d at 173. The defendant claimed that aggravated kidnapping and armed violence predicated on kidnapping with a category I weapon were identical offenses that had disproportionate penalties. Christy, 139 Ill. 2d at 181. The court agreed. Christy, 139 Ill. 2d at 181. It affirmed the appellate court's finding that the penalties were unconstitutionally disproportionate "because aggravated kidnapping is a more serious offense than the lesser included offense of kidnapping; yet, when armed violence is predicated on kidnapping with a category I weapon, kidnapping is, in effect, enhanced to a Class X felony and is punished more severely than aggravated kidnapping." Christy, 139 Ill. 2d at 174.
 Relying heavily on Christy, the court in Lewis held that the penalties for armed violence predicated on robbery with a category I weapon and armed robbery were unconstitutionally disproportionate. Lewis, 175 Ill. 2d at 423. In that case, the defendant was charged with one count of robbery, one count of armed violence predicated on robbery committed with a category I weapon, and one count of armed robbery. Lewis, 175 Ill. 2d at 414. The defendant brought a pretrial motion to dismiss the armed violence count claiming the penalty for that charge violated the proportionate penalties clause because it was greater than the penalty for armed robbery. Lewis, 175 Ill. 2d at 414-15. The circuit court agreed, and the supreme court affirmed. Lewis, 175 Ill. 2d at 415, 424. The ...