We lack the evidence to do more than shade the probabilities?

Does "we lack the evidence to do more than shade the probabilities" mean " we lack the evidence, so we cannot do more; we'd better shade (does the "shade" mean "put aside"?) the probabilities"?

Context:

Carl Sagan was proud to be agnostic when asked whether there was
life elsewhere in the universe. When he refused to commit himself,
his interlocutor pressed him for a 'gut feeling' and he immortally
replied: 'But I try not to think with my gut. Really, it's okay to
reserve judgment until the evidence is in.' The question of extra-
terrestrial life is open. Good arguments can be mounted both ways,
and we lack the evidence to do more than shade the probabilities
one way or the other. Agnosticism, of a kind, is an appropriate
stance on many scientific questions, such as what caused the end-
Permian extinction, the greatest mass extinction in fossil history. It
could have been a meteorite strike like the one that, with greater
likelihood on present evidence, caused the later extinction of the
dinosaurs. But it could have been any of various other possible
causes, or a combination. Agnosticism about the causes of both
these mass extinctions is reasonable. How about the question of
God? Should we be agnostic about him too? Many have said
definitely yes, often with an air of conviction that verges on protest-
ing too much. Are they right?