Marxism
Marxism is a socio-economic, political, and philosophical theory developed primarily by Karl Marx (1818-1883) and Friedrich Engels (1820-1895).He  explains that  people  see  the  world  with love  and  gratitude,  however,  this  world  is  also  full  of  bad people who want to exploit the others by fulfilling their worse intentions (See page 22)
The  above  explained  text  citation  is  the  clear  depiction  of  the  application  of  the "Marxist" theory. The writer describes the  poor  and  unlucky  condition  of  the common people after the end of the Civil War. He is of the view that great societal change occurs when some famine or warrior condition persists for long duration of time. In  addition,  in  the  above  mentioned  text  citation,  the author  explains  the Irish people's condition when they used to deal with  corn  and  severe  scarcity of potato prevailed all around for the year of 1847. It articulates Marxist concerns, propounded by Karl Marx and Friedrich Engels, about economic determinism and class struggle in consequence of dialectic opposition between the oppressor and the oppressed leading to betterment in the society. The passage presents a critique of unjust civil practices caused by the economic elements due to civil war, and the same is the aim of Marxist criticism
? Economic conditions and social relationships: 
The story of the Boyle family shows how the material conditions influence behavior and beliefs and explains the power dynamics based on economic status though the conflicts that affect the family who is enduring oppression under industrial capitalism. Moreover, the creation of a classless society and an end to exploitation as predicted by Marx has been equated to the situation in O' Casey's play where the oppressed attempt to pull themselves out of the swamp of tyranny and make progress to lead a better life through freedom. There is no doubt that the work constitutes a sharp criticism of the organized institutions of Civil War and their respective representatives, just like "Jack Boyle," who has been represented as a failed captain and leader of his family.The relation between text and production is a relation of labour". The Marxist critic simply is a careful reader or viewer who keeps in mind issues of power and money. Key concepts include:
? Class struggle between the proletariat (working class) and bourgeoisie (ruling class) 
? Economic determinism: the idea that economic relationships determine social structures 
? Historical materialism: viewing history through the lens of class struggles 
? Alienation of workers from their labor and its products 
? Critique of capitalism as an exploitative system
Main Marxist Ideas Relevant to Sean O'Casey's Juno and the Paycock: 
In the story of "Juno and  the Paycock", the narrator explains the nature of human being as well as his observing power  towards  the  surrounding.So Marxists generally view literature "not as works created in accordance with timeless artistic criteria, but as 'products' of the economic and ideological determinants specific to that era" (Abrams 149). Literature reflects an author's own class or analysis of class relations, however piercing or shallow that analysis may be.
Marxist literary theory is predicated on the idea that literature is a product of social forces and ideology. However, Terry Eagleton insists that "The literary text is not the 'expression' of ideology, nor is ideology the 'expression' of social class.His works: "The Communist Manifesto" (1848), "Das Kapital" (1867) developed theories of historical materialism and class struggle and critique of capitalism. Karl Marx perceived human history to have consisted of a series of struggles between classes--between the oppressed and the oppressing. Whereas Freud saw "sexual energy" to be the motivating factor behind human endeavor and Nabokov seemed to feel artistic impulse was the real factor, Marx thought that "historical materialism" was the ultimate driving force, a notion involving the distribution of resources, gain, production, and such matters....?