Reason is inherently expansionist. It seeks universal application.

— Peter Singer

Robots already perform many functions, from making cars to defusing bombs - or, more menacingly, firing missiles. Children and adults play with toy robots, while vacuum-cleaning robots are sucking up dirt in a growing number of homes and - as evidenced by YouTube videos - entertaining cats.

— Peter Singer

Some of the conclusions that I draw are very different from the ethical views most people hold today. That, however, is not a ground for dismissing them. If every proposal for reform in ethics that differed from accepted moral views had been rejected for that reason alone, we would still be torturing heretics, enslaving members of conquered races, and treating women as the property of their husbands.

— Peter Singer

Suppose that we believe that in 200 years, people would be prepared to pay a million dollars (that's in today's dollars, not inflated ones) to be able to have an unspoiled valley. Now imagine that today we can profit by cutting down the forest in the valley, which will never regrow. If we apply an annual discount rate of 5 percent, compounded exponentially, how big would that profit have to be to justify the loss of a million dollars in 2210? The answer, surprisingly, is just sixty dollars! That's all that a million dollars in 200 years is worth, at that rate of discount. Obviously, then, if we use a 5 percent discount rate, values gained one thousand years in the future scarcely count at all. This is not because of any uncertainty about whether there will be human beings or other sentient creatures inhabiting this planet at that time, but merely because of the compounding effect of the rate of return on money invested now.

— Peter Singer

The capacity for suffering – or more strictly, for suffering and/or enjoyment or happiness – is not just another characteristic like the capacity for language or for higher mathematics. Bentham is not saying that those who try to mark ‘the insuperable line’ that determines whether the interests of a being should be considered happen to have selected the wrong characteristic. The capacity for suffering and enjoying things is a prerequisite for having interests at all, a condition that must be satisfied before we can speak of interests in any meaningful way. It would be nonsense to say that it was not in the interests of a stone to be kicked along the road by a child. A stone does not have interests because it cannot suffer. Nothing that we can do to it could possibly make any difference to its welfare. A mouse, on the other hand, does have an interest in not being tormented, because mice will suffer if they are treated in this way.

— Peter Singer

Their reliance on biblical quotations does not augur well for their openness to moral reasoning....

— Peter Singer

The merely conscious being does not have a preference for continued life. Perhaps while having a pleasurable experience it has a preference for that experience to continue, or while having a painful experience it has a preference for that experience to end, but it will not have any preferences for the long-term future, and the desires it has do not survive periods of sleep or temporary unconsciousness, because unlike a self-aware being, it has no conception of its own future existence after a period of sleep. Thus, if we are concerned only about the thwarting of preferences, for a merely conscious being, painless killing and administering an anesthetic seem to be equivalent. Killing does not thwart any more desires than putting the being to sleep. The being will be able to continue to satisfy its preferences after it awakes, but from the being's subjective perspective it is as if a new being, with new preferences, came into existence.

— Peter Singer

The new freedom of expression brought by the Internet goes far beyond politics. People relate to each other in new ways, posing questions about how we should respond to people when all that we know about them is what we have learned through a medium that permits all kinds of anonymity and deception.

— Peter Singer

The prescription of the equality of human beings is not a description of an alleged actual equality among humans: it is a prescription of how we should treat human beings.

— Peter Singer

There are some things that, once lost, no amount of money can regain. Thus, to justify the destruction of an ancient forest on the grounds that it will earn us substantial export income is problematic, even if we could invest that income and increase its value from year to year; for no matter how much we increase its value, its could never buy back the link with the past represented by the forest.

— Peter Singer