These couple of talks are part of a workshop and a panel at ASU on Can science tell us right from wrong. The panel had both scientists and philosophers, and yet I was surprised at the way philosophy was denigrated by some on the panel (you have to see the panel discussion for that or the opening talk by Sam Harris). Nevertheless, there is some fascinating discussion on this very tricky topic. Here are two talks that especially stood out for me. The first one is by Simon Blackburn, where he brings up places where it is hard for science to provide adequate answers, unless one defines science in a very broad term that incorporates reason and rationality more broadly - and be inclusive of philosophy. The talks here are relatively short (about 10-12 minutes in length). So here is Blackburn (tip from Laura Sizer):
And here is the talk by Steven Pinker:
The discussion that followed runs up for about 45 minutes, and you can watch it in three parts (part 1, part 2, part 3). If you are interested in some good discussion of whether an ought can be derived from an is, tune in to 10 minutes into part 2, and keep watching into the first 5 minutes of part 3 (Blackburn's takedown of Krauss here is entertaining).
In any case, these are fascinating talks and you can watch them all here.
One other note: When you go to the link above, you will also find a lecture by Sean Carroll at the bottom (I could not embed it here, nor could I find a separate link to it). The lecture is titled, Remarkable Creatures: Epic Adventures in the Search for the Origins of Species, and is about the voyages of Wallace, Bates, and Darwin in the nineteenth century. The lecture is very good and provides some fascinating details of Wallace's trips to the Amazon and southeast Asia. Perhaps, more importantly, it captures the spirit of wonder in these three important figures of biology. I highly recommend this lecture (it is about 50 minutes long, but is entertaining)! So scroll down to the bottom to find Sean Carroll's lecture.