This question is very associated to one more famous question, If the clock rewound, would organisms evolve the same way they did before? But I don't want to ask for the last one, although similar, the answer to the second question not necessarily resolve the first one.
I'm interested in why the main focus of research in the first question is the empirical approximation, see for example the now classic study of the Grant's married couple (http://faculty.uca.edu/benw/biol4415/papers/GrantGrant2002b.pdf)
Clearly the answer to my question could be that I've not searched too well, whether this is the situation, when the question about the predictability of the evolution is assumed by empirical approximations, they turn it into another discussion, like, are there patterns of the macroevolutionary process, that could be repeated if the world's clock rewound? Or the reason of the avalanche of convergent evolution. And by the way they omit the discussion of the predictability at the microevolutionary scale.
I think that we can discuss this problem since an ontological and epistemological optic, We can say that the main reason for some people think that evolution is unpredictable is because, we are methodological and conceptually limited.Then we must defend the idea that the real nature of the evolutionary process is a chaotic deterministic process or something like that. The opposite situation is that we can say that the empirical studies are correct about the nature of the evolution, because this last, although has deterministic process like the migration or the natural selection, it resides in the random nature of the DNA or chromosome mutation
http://faculty.uca.edu/benw/biol4415/papers/GrantGrant2002b.pdf