1. Necessity plays a leading role in the process of historical development and plays a decisive role in the development of historical process, while contingency only plays a role in accelerating or delaying historical development. For example, the May 4th Movement marked the transformation of China's revolution from the old democratic revolution to the new democratic revolution. So why use it as a sign of change? This involves the inevitability and contingency of historical development. The May Fourth Movement has a profound historical background: the Revolution of 1911 did not complete the historical task of anti-imperialism and anti-feudalism, which prompted the people of China to continue to explore new ways to save the country and the people; Beiyang warlords betrayed the country abroad and suppressed the people's revolution at home, which deepened the national crisis; Imperialism pursues the policy of "divide and rule" and invades China, fostering various warlords to scuffle, which makes the domestic people struggling; During the "World War I", China's national capitalist industry further developed, which made the proletarian power develop and strengthened, and laid the class foundation for the May 4th Movement. The development of the new culture movement and the spread of socialist ideas after the October Revolution promoted people's ideological emancipation and laid the ideological foundation for the May 4th Movement. The victory of Russian October socialist revolution pointed out the way for China revolution. All these constitute the basic conditions for the transition from China revolution to new-democratic revolution, and the transition from old-democratic revolution to new-democratic revolution in China is an inevitable trend of historical development. In other words, even if there was no such historical event as the May 4th Movement, there would have been another event in China in the first half of the 20th century, which was a landmark event in the transformation of China's revolution from the old democratic revolution to the new democratic revolution, but the May 4th Movement accelerated the transformation of China's revolution from the old democratic revolution to the new democratic revolution. The events that can also be explained are: Qin Shihuang and Sui Wendi unified China; China became a semi-colonial and semi-feudal society; China embarked on the socialist road; The outbreak of the first and second world wars; The drastic changes in eastern Europe and the disintegration of the Soviet Union are the result of the combined action of inevitability and contingency, but they have played different roles in the historical development process.

Second, the inevitability of influencing historical development is manifested through countless accidental events. Therefore, when studying history, we must be good at finding out the inevitable laws hidden in the process of historical development through accidental events. Take the failure of the Revolution of 1911 as an example. 19110 In June, after the success of Wuchang Uprising, the provinces became independent from the Qing Dynasty, and the rule of the Qing Dynasty collapsed. However, in March, 19 12, Yuan Shikai became the provisional president of the Republic of China and usurped the fruits of the victory of the 1911 Revolution. Why did the Revolution of 1911 fail so quickly? There are many reasons: the Three People's Principles, as the program of bourgeois democratic revolution, did not clearly put forward a thorough anti-imperialist and anti-feudal proposition and could not mobilize the broad masses of the people for revolution; As a bourgeois political party leading the revolution, the League was disorganized and split at the same time as the revolution developed smoothly, so it could not play a leading role. In the process of launching the uprising, the revolutionaries simply relied on communist party and the new army, but did not mobilize the broad masses of the people and establish a strong revolutionary armed force; After Wuchang Uprising, with the rapid development of the national revolutionary situation, the constitutionalists and old bureaucrats in various provinces speculated on the revolution one after another, which led to the serious impurity of the revolutionary ranks. They controlled most of the local political power and made trouble in the revolutionary camp. After the establishment of the Nanjing Provisional Government, in the Letter to Friends, it was acknowledged that a series of unequal treaties signed by the Qing government and imperialist countries were still valid. Under the pressure of imperialism, under the attack of the constitutionalists and the old bureaucrats, and under the deception of Yuan Shikai, the revolutionaries were forced to compromise and cede power to Yuan Shikai, which eventually led to the failure of the Revolution of 1911. The crux of all these reasons stems from one thing: China's national capitalism was born in a semi-colonial and semi-feudal society, and its development was never fully developed under the double oppression of foreign capitalism and domestic feudalism. The capitalist economic power is relatively weak, which leads to political weakness and compromise of the national bourgeoisie. The reason why the Revolution of 1911 didn't complete the anti-imperialist and anti-feudal task, didn't completely change the nature of China's semi-colonial and semi-feudal society, and the road of bourgeois republic didn't work in China, in the final analysis, was that China's capitalism was not fully developed and the bourgeoisie was weak and compromised. The failure of the Taiping Heavenly Kingdom Movement, the Reform Movement of 1898 and the Boxer Movement in China's modern history can also be analyzed in a similar way.