This is a pretty interesting exchange between Russell Blackford and Sam Harris on the topic of Harris' new book 'The Moral Landscape'--in which Harris argues that science can determine human values. Harris recognizes that he is in an extreme minority on this issue. Almost all religious people would disagree, and the vast majority of secular scientific-minded types would also disagree, he acknowledges. But he claims that morality is essentially the 'science of human flourishing' or well-being, and since science can determine certain activities are worse for human flourishing than others (via sociology, economics, neurobiology etc.), it can therefore determine human values. That is the central argument of the book.
Harris wrote a piece responding to critics in general, but focused on Blackford since he felt he was the most thorough and insightful. Harris' response is thorough in that he doesn't really evade Blackford's points, but his responses either completely miss the point, or dismiss a point as insignificant, when it isn't.
For example, in response to the central critique of the argument of the book--that Harris presupposes, rather than demonstrates, that 'human flourishing' or 'well-being' is an ultimate good while human misery is evil--Harris essentially says "well, yeah, I did that, but I'm allowed to do that, and must do that. There's nothing wrong with that presupposition." Yes you're allowed to, but the point of Blackford, and all the critics of the argument, is that it's the philosophical presupposition that is determining the value NOT science. Science can only (in theory, anyway) let us know the best way to achieve our ends, once we have determined our values. Harris seems to completely miss the point, or not understand it. He even says "The fatal flaw that Blackford claims to have found in my view of morality could just as well be located in science as a whole -- or reason generally." -- Which is of course true, and science and reason are subject to the same critique. But science and reason, as abstract entities, didn't falsely claim that they could determine moral values, Sam Harris did. Harris seems oblivious to what his own argument even is, namely that science can determine human values, and the fact that his critic just demonstrated this to be false and Harris just conceded that it was false!
Also, his analogy to health does nothing to advance his case because, similarly, the objective knowledge about how best to be healthy is not the same as saying we must value health primarily, ultimately, or at all. The knowledge of how to be healthy doesn't demand ascent as to the value of our health. Some think it's very important, some think it's pretty important, some think it's mildly important, some don't think it's important. Science can not evaluate these opinions, it can only say "health is important if you want to live a long time" for example, but that isn't 'determining a value', it's evaluating a value that is already given. If I value 5 cheeseburgers a day, video games and a short lifespan over a healthy diet, exercise and a long lifespan, science can say nothing about this health value system of mine.
Anyways, Harris' response is ultimately pretty terrible and Blackford's review is overly positive, if anything, but good. One other interesting aspect of Harris' response to critics is his complaining that many hadn't read the book (either admittedly, or seemingly). Which is kind of silly when you're out giving hour long lectures at TED about the argument of the book, and doing a huge publicity tour where you lay out your argument thoroughly. People can, in good faith, engage your argument without reading the book. Though they shouldn't label their engagement a 'review' of the book as Deepak Chopra did. But when the foundation of your argument can be gleaned from reading the book jacket, or even just the subtitle, and it's blatantly fallacious, critics shouldn't really be expected to delve much further.