What do you consider hard SF? That term doesn't have a real definition and everyone's conception is different. But I think it's unreasonable to say that Blindsight is not hard at all. On the spectrum of SF, it clearly leans way more towards the hard side.
Or, put another way, if Blindsight is not hard science fiction to you, then I think your criteria for hardness is far beyond almost everyone else's.
What do you consider hard SF? That term doesn't have a real definition and everyone's conception is different. But I think it's unreasonable to say that Blindsight is not hard at all. On the spectrum of SF, it clearly leans way more towards the hard side.
Or, put another way, if Blindsight is not hard science fiction to you, then I think your criteria for hardness is far beyond almost everyone else's.