Hopefully this quotation may explain why an authoritarian approach was necessary to attempt in rescuing Iran from 1400 years of foreign domination (physically or ideological-wise), nation-wide poverty & disease, dis-integration of the territorial integrity of the country, banditry and lawlessness, nation-wide illiteracy, a superstitious society governed by an anti-Iranian Islamic religious establishment, and a thousand other ills which faced Iran at the time that the founder of modern Iran (Reza Shah the Great) decided to put the country on the path towards modernity, progress, and prosperity. Imagine that society, facing the thousands ills that were present at that time, being given full democratic rights, as suggested by these gullible individuals a 100 years after the realities of that period in history, the results would have been nothing short of anarchy or the powerful anti-Iranian Islamic religious establishment capitalizing on their stronghold of Iranian minds and bring further misery to a country that had at that time suffered for 1400 years...
“Authoritarian political structures sometimes work well. They offer opportunities to make rapid change and to impose firm leadership which more accountable systems lack. In the hands of honest leaders of determination and vision, they give opportunities for stability and long-term planning which democratic regimes often find difficult to achieve.”
(Kay & Silberston, 1995, National Institute Economic Review, Aug: 84-95)
Certainly authoritarianism may also lead to negative outcomes if those that exercise it do not have the interests of the nation at heart - but again any sane human being that makes an informed evaluation of the efforts of modern Iran's founding father and his successor will come to the conclusion that their actions were made with nothing but the interests of their countrymen and future generations to come. Also, it need to be said, that even with the best interests at heart there may also be negative outcomes to decisions that are made, however in general the approach that was adopted was the only feasible and realistic approach that could have been taken.