Right, the fact that there's significant correlation between schizophrenia and cannabis use is well known, but I not aware that there's any decent evidence for or against causation. Schizophrenics have generally higher rates of substance use/abuse so a higher rate of cannabis use is not not odd, per se.
IIRC, there's also a very high correlation between schizophrenia and early substance abuse/overuse in general (such as high alcohol/caffeine use). Are these substances causal too?
there is casual evidence that alcohol and caffeine increase hospitalisations for schizos. With marihuana its a harder riddle, what is a cause of another, I guess you can ask the same about other substances and origin
