I&#x27;d argue that the main problem with the theory is that there are plenty of places where there is high income inequality (such as the United States, as indicated by the diagram) and something like ISIS seems rather unlikely† .<p>Sure, you can say that inequality may have contributed to the issue, but there are a ton of factors that have resulted in Syria being plunged in Civil War. Pointing to any one as a decisive factor seems like an inevitable simplification. Also, it doesn&#x27;t really answer the question &quot;Why _now_?&quot;. Claiming that something eventually happen is not really predictive if no time frame can be given.<p>† Or I might be overly optimistic about my own country&#x27;s stability.