Is the theory of karman true?

I just read a very interesting, though relatively old, paper, Robert Goldman's Karma, Guilt and Buried Memories: Public Fantasy and Private Reality in Traditional India (JAOS 105.3, 1985).The author takes it for granted that the theory of karman cannot be "true" (in the same way as it is true that fertilizers increase crop yields, p. 415). In fact, if it were, many evidences would have been found in the many centuries of its fortune in South Asia. Hence, it is interesting and telling in regard to the communities who hold this belief notwithstanding its falsity –just like a dream is false, but tells us a lot about the dreamer.
However, I wonder whether a theory of karman could ever be proved to be true in the same way as a fertilizer is (the author does not mention any other example). One is reminded of the controversy about God's existence and the impossibility –according to the present author– to solve it in terms which have nothing to do with it (in other words: truth criteria for fertilizer are not necessarily the only possible ones). The theory of karman is of philosophical (not just psycho-analytical) interest because it is a defensible explanation of the existence of evil/the non-homogeneity of destinies/etc. A further problem in the paper is its insistence that the theory of karman is a moral one. Hence, since it is utterly immoral (because we have to suffer the consequences of former people), it does not hold. However, in most Indian philosophical texts I am aware of, the theory of karman is rather a mechanical explanation of the uninterrupted chain of actions and consequences, lacking any moral character. Lastly, the author's insistence on a Freudian interpretation of the theory of karman is challenging. However, I don't think it has anything to do with the theory of karman as a philosophical concept –rather, with its narrative and social outputs. In this sense, it does not make sense to accuse the theory of karman of lack of consistence on the strength of narratives such as that of Śakuntalā. The philosophical theory of karman and its upholders are not responsible of its use in epics and narratives… no more than Christian theologians are responsible of the use of heaven and hell in contemporary Holliwood films! That said, the essay is fascinating and thought-provoking.