My major concern about leaving enhancement to the marketplace is that then the rich will be able to buy themselves genetically superior children and the poor will not - sharpening the class divisions we have now. That problem could be overcome if, genetic enhancement were available to all, subsidized by the state - and that would, over time, have benefits for society as well.

As for cages themselves, an ordinary citizen who kept dogs in similar conditions for their entire lives would risk prosecution for cruelty. A pig producer who keeps an animal of comparable intelligence in this manner, however, is more likely to be rewarded with a tax concession or, in some countries, a direct government subsidy.

I suppose what's happened recently has confirmed suspicions I voiced in the book, and I think made clearer some of those things that I point out. For instance I have a section of the book where I talk about the possibility of torture.

I think ethics is always there; it's not always a very thoughtful or reflective ethics.

That's a central part of philosophy, of ethics. What do I owe to strangers? What do I owe to my family? What is it to live a good life? Those are questions which we face as individuals.

Habits of thought lead us to brush aside descriptions of cruelty to animals as emotional, for "animal-lovers only"; or if not that, then anyway the problem is so trivial in comparison to the problems of human beings that no sensible person could give it time and attention. This too is a prejudice - for how can one know that a problem is trivial until one has taken the time to examine its extent?

Scholars have long dreamed of a universal library containing everything that has ever been written.