The opinion of the court was delivered by: Justice Freeman
 Docket No. 96884-Agenda 9-March 2004.
 The sole issue in this case is the amount an employer is obligated to compensate an injured employee under the Workers' Compensation Act (820 ILCS 305/1 et seq. (West 1996)). The resolution of this question requires this court to construe the phrase "working concurrently with two or more employers" in the context of workers in seasonal industries.
 The pertinent facts are undisputed. Larry Flynn (claimant) drove asphalt trucks for the sibling companies LaSalle County Asphalt, Universal Asphalt, and Advanced Asphalt Company from 1979 through 1996. He was a member of the Teamsters union during that time, and his employment was controlled by the union contract. Because of the weather-dependent nature of the asphalt business, claimant's employment generally began in early spring-March or April-and continued through November or December. During the winter "off-season," claimant generally signed the "referral list" or "call list" maintained by his union and was also "on call" with the asphalt companies. Claimant testified that he was sometimes called back to work by the asphalt companies during the off-season, after he had finished work for the year and before he began the next year.
 Claimant never applied for unemployment compensation during the off-season. Rather, he worked and lived on a farm which he rented from his mother. He also sometimes worked at other employment when it was available. It was during the course of one such temporary employment opportunity that he received the injury underlying the instant litigation.
 On January 16, 1997, Utica Township rented claimant's large snow blower and hired claimant to run it. Jerry Cary, the Township employee who hired claimant, testified that he knew when he hired him that claimant worked for the asphalt companies during the warmer times of the year. The Township and claimant agreed that the Township would pay claimant $67 per hour for the rental, and $8 per hour in wages. Claimant cleared snow for the Township on January 16 and 17, but while working on the latter date, after he had worked a total of seven hours clearing snow, the snow blower shaft sheared. Claimant attempted to repair the blower, but while he was using a chisel to remove the sheared bolt, the chisel jumped and hit claimant's left eye. Despite two surgeries, claimant's eye was eventually completely removed because of a detached retina and repeated intra-ocular hemorrhages.
 Claimant returned to his work as an asphalt driver in 1997, but the Illinois Department of Transportation refused to renew his license in 1998, due to his vision impairment. Consequently, claimant had to seek other employment. He found work as an armed guard at an off-track betting facility. At the time of the hearing, he was earning $9 per hour. If claimant had been able to work as an asphalt driver his wages would have been $22.59 per hour.
 Claimant initiated this proceeding pursuant to the Workers' Compensation Act (Act) (820 ILCS 305/1 et seq. (West 1996)) by filing an application for adjudication of claim with the Industrial Commission in May 1998. The arbitrator concluded that claimant's average weekly wage (AWW) as an armed guard was $360, and that his AWW as a snow blower was $56, but that his AWW "for the permanent occupation in which he was engaged at the time of the accident which permanent occupation was his usual and customary line of employment was $903.60 [$22.59 x 40]." The arbitrator found that the weekly difference between what claimant was actually earning and what he could have earned if not for his accident was $556.40 ($903.60 - $360), and ruled that pursuant to section 8(d)(1) of the Act, claimant was entitled to two-thirds of that differential, or $362.36 per week. See 820 ILCS 305/8(d)(1) (West 1996).
 The Industrial Commission rejected the arbitrator's ruling, in a decision with no majority opinion. Writing for the Commission, Commissioner Smart concluded that claimant was an employee of the Township, and thus was entitled to benefits under the Act for his injury. However, claimant was not employed "concurrently" by the Township and the asphalt companies. Accordingly, what claimant earned from the asphalt companies was irrelevant, and claimant's AWW was $56 per week. Because this was less than he was earning in his employment as a security guard, claimant was not entitled to any wage differential. Instead, the Commission ruled that claimant was entitled only to 160 weeks of compensation at the AWW of $56 per week, according to the Act's scheduled compensation for the total loss of an eye. See 820 ILCS 305/8(e)(13) (West 1996).
 Commissioners Stevenson and Sherman dissented. Commissioner Stevenson believed that claimant was not entitled to any compensation, because claimant was an independent contractor, rather than an employee. However, he agreed with Commissioner Smart that if claimant were entitled to compensation, his compensation should be based on an AWW of $56 per week, because claimant's snow blowing and asphalt truck driving employments were "serial," not concurrent. Commissioner Sherman agreed with Commissioner Smart that claimant was entitled to relief, but would have upheld the arbitrator's determination that claimant was concurrently employed by the Township and the asphalt companies and was thus entitled to wage differential based on the AWW that the arbitrator calculated.
 The circuit court of La Salle County and the Industrial Commission division of the appellate court affirmed the Commission in all respects. A divided appellate court explicitly deferred to the Commission's conclusion on the issue of whether claimant was concurrently employed, reasoning that
 "The parties to this appeal do not argue that the statute is ambiguous or dispute the ordinary meaning of `concurrently.' Instead, they disagree whether claimant falls within the statute under the facts of this case. This issue does not involve statutory construction, and the manifest weight of the evidence standard is applied." 339 Ill. App. 3d 994, 999.
 The majority held that the Commission's determination that claimant was not concurrently employed was not against the manifest weight of the evidence, stating that his "earnings from [the Township] were a substitute for, not a supplement of, his earnings as an asphalt truck driver." 339 Ill. App. 3d at 1000. The appellate majority rejected claimant's argument that his "occupation" for purposes of a wage differential award under section 8(d)(1) of the Act was his "usual and customary line of employment" as an asphalt truck driver. The appellate court noted that the statute specifically referred to the occupation "in which he is employed at the time of the accident." The majority reasoned that by the use of this modifying language, the legislature had barred consideration of an employee's earning potential in any occupation except the "job he was performing when injured." 339 Ill. App. 3d at 1001.
 Justices Goldenhersh and Holdridge dissented, arguing that the majority and the Commission failed to take into account the "recurrent sequence of claimant's employment." 339 Ill. App. 3d at 1002 (Goldenhersh, J., dissenting, joined by Holdridge, J.). The dissent would have held that claimant was concurrently employed as a snow blower and an asphalt truck driver, given the long and steady history of periodic temporary seasonal layoffs.
 Claimant petitioned this court for leave to appeal (177 Ill. 2d R. 315(a)), which we granted.
 The parties differ on the standard of review and the correctness of the Industrial Commission's ruling. Claimant argues that the decision of the Commission should be reviewed de novo and set aside, while Utica argues that the Commission's decision should be confirmed because it was not against the manifest weight of the evidence.
 First, we consider the standard of review. Claimant argues that the appellate court erred in deferring to the Commission because the only question was the application of the law to undisputed facts, a situation in which he contends review should be de novo. Utica disagrees, arguing that the appellate court was correct in ...