I came into contact with Marxism twenty-five years ago. Twenty years ago, I came into contact with the Maoists (also called the M-L groups). After intense debates with them, I finally joined one group, the Communist League of India (Marxist-Leninist).
But I only began reading Trotsky a year ago. It was a revelation! It was writing in the best tradition of Marx, Engels and Lenin.
It came as a shocker to me. I had always taken Marxism-Leninism as a science; I did not consider myself to be a dogmatist. In fact, one of my favourite quotations is from the Great Debate between the Communist Party of China (CPC) and the Communist Party of the Soviet Union (CPSU): Marxism-Leninism is a science, and science fears no debate. But then why had I not read Trotsky earlier? Because no one in the Maoist movement read Trotsky. The journals of the various Maoist groups did not carry any articles on Trotsky’s views or on the debate between Trotsky and Stalin; in the discussions within my group or with other groups, Trotsky was never discussed. Some independent Marxist magazines like the Monthly Review occasionally carried articles by Trotskyites or by independent Marxists criticizing this or that aspect of the Stalin period, but they were simply ignored. All criticisms of Stalin (apart from that done by Mao and the CPC) were dismissed as bourgeois propaganda.
I assumed that Stalin and the CPSU must have seriously debated and refuted Trotsky’s arguments on the basis of Marxist-Leninist theory. They must have tried to convince Trotsky of the erroneousness of his views. I was not very sure why was he expelled from the CPSU and sent into exile, but I assumed there must have been good reason to do so. Then, Mao and the CPC too had rejected Trotsky, they must have analysed his arguments and rejected them on the basis of Marxism-Leninism. And then, the entire leadership of the Third International too had rejected Trotsky’s criticisms of Stalin. If this entire galaxy of revolutionary leaders had considered Trotsky’s arguments to be erroneous, they had read, discussed and rejected his views, had even considered him to have become in the 1920s-30s an enemy of the working-class movement, why then should I waste my time reading Trotsky, when there was so much else to read? So, I did not read Trotsky.
After reading Trotsky’s History of the Russian Revolution a year ago, I realized I should have read it years ago. It brilliantly revealed aspects of the Russian revolution about which I had absolutely no idea; it was a book which deepened my “faith” in the science of Marxism-Leninism; there was nothing ‘anti-working class’ in it. I understood why Paul Sweezy has written that it was this book which made him a Marxist.
And so, I read more Trotsky. I next read Trotsky’s The Revolution Betrayed. And I was stunned. It was a thoroughly scientific criticism of Stalin’s theory and policies. It revealed facts about the Stalin period, about the domestic and foreign policies of the Soviet Union during Stalin’s leadership, which were very disturbing, actually unbelievable, which if true meant that Stalin’s policies were not oriented towards advancing socialist construction in the Soviet Union and instead were taking it in the opposite direction, towards restoration of class society. Many of Trotsky’s criticisms were on the same lines as Mao’s criticism of Khrushchev. There was no slander or abuse of Stalin; on the contrary, it actually did not blame the individual Stalin for the mistakes, and instead traced the mistakes to their material basis, to the problems inherent in socialism as a transition period from capitalist society to a classless society. Nevertheless, having heard so much criticism of Trotsky, I still felt there must be another side to the picture presented by Trotsky. So I read Stalin’s reply to Trotsky’s criticisms. I discovered, to my utter surprise, that Stalin’s replies were weak and evasive, that he was twisting Lenin’s quotations to support his theories, that on many issues he was distorting Trotsky’s arguments and then charging him with slandering Leninism. I then tried to find out what Mao had written about Trotsky. Once again I was surprised. I found that Mao was silent on Trotsky; I have not been able to find even a single paragraph written by Mao or the CPC on Trotsky’s criticisms of Stalin’s policies, despite the fact that Trotsky had made a masterly analysis of the reasons for the rise of a bureaucracy in a socialist society, and Mao had to grapple with the same problem after the Chinese revolution and because of which there took place intense inner party struggles within the CPC after the revolution. However, I did come across occasional comments about Trotsky, dubbing him a renegade, an anti-Leninist, an enemy of communism, and so on. This was most disappointing; the approach of the CPC towards Trotsky was exactly the same as Khrushchev’s criticism of Stalin, for which the CPC had rightly denounced Khrushchev.
Likewise, the Maoist movement in India is silent on Trotsky’s criticisms of Stalin, criticisms which are totally in the spirit of Marxism-Leninism. Instead, ‘Trotskyite’ has become an abuse; if someone has to be denounced as a revisionist, or as betraying the ideology of Marxism-Leninism-Mao Tse-tung thought, he is dubbed as a Trotskyite. It is an approach which was condemned by Lenin: “Not to reply to an argument of one’s opponent on a question of principle, and to ascribe only ‘pathos’ to him, means not to argue but to turn to abuse.” 
One may not agree with Trotsky, but he has to be read, discussed and replied to. That is the only Marxist method; it is the method of science. I therefore decided to summarize what little I have read of the Stalin-Trotsky debate, and propagate it, in an attempt to provoke a debate. Considering the immense prejudice in the Maoist movement as regards anything to do with Trotsky, I am not sure if my effort will elicit any response; nevertheless, I have decided to make my effort.
It is only a very modest and incomplete attempt. For, I have not read much of Trotsky, nor much of Stalin. This is a summary of the most important issues raised by Trotsky in his work the Revolution Betrayed, and some other writings; and Stalin’s reply to Trotsky’s criticism’s, as compiled in the two collections of his articles and speeches On the Opposition and Problems of Leninism. Even if just a few readers ruthlessly dissect this work, I would feel my effort to have been amply rewarded.
 V. I. Lenin, Some Remarks on the 'Reply' by P. Maslow, Collected Works, Eng. Edn., Foreign Languages Publishing House, Moscow, 1963, Vol. XV, p. 255