In this thesis ”The Dialectics of Technology: Ambivalences and Ruptures in Herbert Marcuses’ Philosophy of Technology” I present a thorough analysis of Herbert Marcuses’philosophy of technology as it developed from the late 1940s until his death in 1979. Whereas, previous studies have tried to reduce his philosophy of technology to one coherent project, I argue that his philosophy of technology is characterised by ambivalences and ruptures and therefore cannot be reduced to such a coherent totality. Marcuses’ philosophy of technology vacillates between what I, with Andrew Feenbergs’ concepts, callan instrumentalist and substantialist notion of technology. An instrumentalist notion is one where technology is understood merely as a tool to be wielded by external actors, in Marcuses’ case that of the capitalist class and the state. In contrast to this, Marcuse also precents a substantialist philosophy of technology, where it is imbued with its own agency and direction.The previous scholarship has largely reduced Marcuses’ philosophy to one of these positions, rather than emphasising how both of them are present through out the text. Furthermore, I argue that his substantialist understanding of technology itself is characterised by ruptures and ambivalences, where technology is viewed both as inherently emancipatory and as inherently subjugating. It is in regard to this duality I argue that his philosophy of technology should be understood as dialectical, in the sense that technology at the same time can be a central part of human subjection and one of the most important vehicles for emancipation. In relation to this, I agree with Samir Gandesha that one of the most fruitful directions Marcuses’ philosophy opens is an understanding of technology as bearer of a historical substance, that is to say that technology is imbued with certain goals, desires and world-views beyond those of the wielder, while at the same time understanding that this substance can be changed through historical processes. Beyond the more exegetic presentation of Marcuses’ philosophy and the critique against the previous scholarship, I argue for critical theory, and especially Marcuses’, relevance for current debates around technology and automation. In the current debates between left wing accelerationist cheerleaders of technology and those radicals more sceptical of technologies emancipatory potential, an investigation into the nature of technology itself is severely lacking. While, the former uncritically embraces the technology arisen in capitalist society and views it as a direct path towards a utopian post-scarcity communism,the latter solely focuses on technology as a tool of capitalist class power. In relation to this, I argue that the historical and dialectical understanding of technology that can be salvaged from Marcuses oeuvre would be a welcome and useful addition to the debate.