First of all let us consider its qualifications as a film before coming to its content and finally its name. A feature film should have drama. Well this film singularly lacks drama except for some artificially contrived debates among some of the protagonists over jaded philosophical issues and the contrived ending is meaningless instead of being climactic. There is some good cinematography but once again it is contrived and not part of the story line except in the third story. The film could have been shorter and tighter without many of its contrived scenes.
Coming to the content, the focus of the film is on organ replacement and donation. The medical procedures for organ replacement are extremely costly and so accessible only by rich or well connected people either in this country or abroad. So it is not of any concern for the billions of poor people and if some of them suffer from organ malfunction then they have no option but to be disabled or die. Instead the poor are sufferers of a racket of organ stealing which is rampant in this country as is the illegal clinical testing of drugs without their informed consent on poor patients who visit hospitals. The issues of cruelty to animals in drug testing and the suffering of the poor from whom organs are stolen do come into the narrative in a peripheral way but they are not taken to their logical conclusion and are left hanging in the air. This is because the overwhelming stress in the film is on organ replacement and its philosophical and ethical basis. Since this is a phenomenon that is a part of capitalist medicine catering to a very few rich people across the world, I at least fail to see how it can be an all important existential question of our times to catapult this film on the basis of its content into one of the best ever given that in film making terms also it is quite pedestrian!!
Finally coming to the name of the film which refers to a philosophical conundrum posed by the ancient Greek philosophers about whether a ship, all of whose parts have been replaced during repair is still the same ship. Now, even in those times when scientific knowledge was not advanced enough, this paradox was a thought experiment that was of peripheral concern to the philosophers such as Socrates and Plato, whose main concern was with the meaning of human existence. Currently in the light of modern scientific knowledge about our bodies, in the case of human beings at least, this paradox has become obsolete and useless. Our bodies are mostly made of cells which vary in age from a few days to about ten years except for a few cells in the cortex of the brain which are there from birth to death and determine the continuity of life over this period. Thus, our bodies are continuously changing and so are our personalities because we imbibe new ideas from our social environment and discard others that we may have acquired earlier either consciously or unconsciously. As Descartes famously said - "I think therefore I am"!! Medical replacement of an organ, thus, does not pose any great philosophical or existential problem per se though obviously it affects the physical, mental and emotional makeup of a person especially in the case of a blind person who gets eyesight. The ending tries to refer to another of Socrates' thought experiments - the cave allegory. Suppose we are all prisoners in a cave and are able to see only the wall in front of us and the shadows falling on it due to the sunlight behind us. Then we will think that those shadows are the reality. Only when we come out of the cave will we realise that the shadows are not the reality. One is left wondering as to whether the director is hinting that the people who got organ replacements are akin to people who have come out of a cave in which they were earlier. Even if that is not so and the director is trying to picturise the play of illusion and reality, then also he is not doing anything path breaking because the likes of Ingmaar Bergman have pretty much exhausted this line of picturisation in a much more accomplished manner.
One gut response answer to whether a film is great or not is whether one would like to see it again and again. Well, another multiple story film which has a deep philosophical undercurrent (and mind you in this film there is no overt philosophical debating as in the Ship of Theseus because the philosophical problematic comes out from the gripping narrative itself) is the Akira Kurosawa classic "Rashomon". I have seen this film a number of times and would love to see it again and again because each time I find myself cogitating over which of the stories is the true story and my answer depends on my own philosophical position in life at the time I am seeing this film. I am afraid I can't say the same for the "Ship of Theseus" which is eminently forgettable and can't be considered to be a great film by a long shot let alone hold a candle to Rashomon. One just has to compare the virtuoso film making, cinematography, content, drama, story telling, climax and the superlative acting of Rashomon with Ship of Theseus to understand that the latter is nothing but a load of crap!!
This brings me to the way in which the media these days is manipulated by the capitalists and in turn manipulates the intelligentsia. A total non-problem that concerns only the rich is cynically magnified into being an existential problem of our times and the intelligentsia goes ga ga over it.