Are out there practical applications of dialectical materialism? something on sciences, engineering or art?
▻ AMBIGUITY OF 'PRACTICAL APPLICATION'
There is no doubt that politicians, academics, activists and others have used the label, 'dialectical materialism', some in good faith and others not, to describe or justify the policies they adopted and the analyses they made. In that sense dialectical materialism has had a great deal of practical application.
The more interesting question, at least philosophically, is whether dialectical materialism actually works as a tool of analysis or a principle of scientific method to yield predictions, to illuminate a subject-matter, to explain a historical development, to forecast the rise or collapse of economic systems.
▻ DIALECTICAL MATERIALISM - WHAT ARE WE TALKING ABOUT ?
No-one who snaps their fingers and produces a quick formula is worth listening to. So I had better avoid that mistake myself. Dialectical materialism ('DM') is often equated with the triad, 'thesis-antithesis-synthesis', but Engels was mainly responsible for this. While it is not a complete caricature of Marx's thought it crudifies it.
Marx was not a materialist in the sense that widely prevailed in the 19th century. He did not believe that reality is wholly composed of 'stuff', of atoms with forces between them governed by laws ('mechanical materialism'). He also did not believe that every mental state of event is identical with some material or physical state of event. He was a materialist mainly in the looser but anyway different sense that he was concerned with the transformation of natural objects into produced objects, objects transformed by labour into objects that satisfy needs or serve other human purposes. What matters centrally in history is how human beings produce their means of subsistence. 'The German Ideology' makes this clear :
The way in which men produce their means of subsistence depends first of all on the nature of the actual means they find in existence and have to reproduce. As individuals express their life, so they are. What they are, therefore, coincides with their production, both with what they produce and how they produce. The nature of individuals thus depends on the material conditions determining their production. ('The German Ideology' (1846), ed. R. Pascal, New York: International Publishers, 1967, p.7.)
This talk of 'material conditions' is poles apart from mechanical materialism. Human beings are thinking, imaginative agents who can plan and imagine beyond the confines of mechanical materialism :
We presuppose labor in a form that stamps it as exclusively human. A spider conducts operations that resemble those of a weaver, and a bee puts to shame many an architect in the construction of her cells. But what distinguishes the worst architect from the best of bees is this, that the architect raises his structure in imagination before he erects it in reality. At the end of every labor-process, we get a result that already existed in the imagination of the laborer at its commencement. (K. Marx, 'Capital', I..3.7.)
Further in 'The Holy Family' :
History does nothing, it 'possesses no colossal riches,' it 'fights no fight'! It is rather man - real, living man - who acts, possesses, and fights in everything; it is by no means 'History' which uses man as a means to carry out its ends as if it were a person apart, rather History is nothing but the activity of man in pursuit of his ends. (Marx & Engels, 'The Holy Family', ch. VI, 1845 : www.marxists.org/archive/marx/works/1845/holy-family/ch06_2.htm.)
So much for materialism. Where does 'dialectical' fit in ? The story is roughly as follows. There are objective conditions of human life which belong to a world of nature independent of consciousness [thesis]. We confront this world with our needs and other purposes [antithesis] and transform it through labour into into objects of production that satisfy needs or serve other human purposes [synthesis]. This process generates tensions and contradictions in social life; new technologies of production generate different patterns of ownership, which create social and economic inequalities. Classes emerge, rise and fall. The ultimate synthesis will be the domination of a single class whose victory will create a classless society in which the full potential of human creativity will be released.
That's the picture. Don't try to read off my own views.
▻ PRACTICAL APPLICATION (1) - EX POST FACTO DESCRIPTION
Human history can be read in the way described but DM appears to have little if any predictive value. Everything that happens can be interpreted in line with it. DM could be totally true yet not be able, as it was not able, to forecast the new technologies of the late 20th and early 21st centuries and the resultant social and economic changes. That we can after the event describe what has happened in DM terms hardly confers much value on it. Like an autopsist it can explain why the patient died but not how long s/he would live.
▻ PRACTICAL APPLICATION (2) - FALSE TELEOLOGY
Even if DM had predictive power, it grafts a teleology on to history which it can't really justify. Since we can't predict inventions, hence new technology, then we can't predict new patterns of ownership. Hence we can't predict what social classes will emerge into dominance. There is no guarantee, whatever Marx may have thought to the contrary, that the end-point of history - or the start of 'truly human' history - will be the emergence of a class that will abolish all classes.