Joe Friggieri's article Ethics Beyond Convention (November 21) hasn't changed my views that his examples of "how an 'ought' can follow from an 'is'" are unconvincing. My point in citing the so-called naturalistic fallacy to begin with was that an "is" does not imply an "ought". In simpler English, from the fact that something is the case, for instance, that the exact biological beginning of life is at point x (taken that it can be established), nothing follows about how we are morally obliged to treat it at that stage. My contention was, and still is, that moving from the statement that life begins at point x to the statement that taking it, or terminating it, at that stage is morally wrong requires additional assumptions that are non-factual; that are related to one's beliefs and moral outlook the origin of which may be religious or secular, depending. The demonstrable fact that people today disagree on most serious moral matters is a reflection of this fact.

I did not deny that "an 'ought' can follow from an 'is'" if that means that the facts of the case can be relevant to how we decide things morally. Indeed, I endorse the position that the facts of the case are always relevant. I would also endorse his view that in the ordinary intercourse of everyday life or "context of normal procedure", one should keep one's promises and that the integrity of our social relationships, nay their very possibility, depends on conventions like telling the truth, keeping promises, and so on. But the fact that, as Prof. Friggieri says, "it is impossible to give an exhaustive description of all the circumstances which theoretically could create a special context" substantially weakens the moral "ought" that follows from the convention rendering it conditional or contingent not absolute, in other words not an ought (in the strict Kantian sense) at all. If he admits to this then we have no disagreement. But he doesn't as the second part of his article shows.

In the first part of his article he answers my objections to his examples. I am not going to counter-respond here so as not to lose the reader by rendering the argument too technical. I shall comment briefly on one. "From the fact that animals feel pain, it follows that I am morally obliged not to do anything that would cause them avoidable suffering."

Prof. Friggieri is annoyed by my contention that he factors in a distinction between causing pain to human and to non-human animals, which opens him to the charge of speciesism. On my part I find no problem admitting to the charge, while I admit to the force of the objection. Being a human being myself I would privilege a human over a non-human animal if I were to choose, but I do not claim an objective viewpoint. Mine is a self-confessed human viewpoint, and a particular Western one at that. If he wants to sustain that his view is objective then he has philosophical problems with the charge of speciesism because that charge challenges precisely his claim to objectivity.

It is to that claim that I want to devote this article. He explains "objectivity" as the view "that there are certain facts about the way things are in the world that determine the truth or falsity of the statements brought against them". He proceeds to give examples: that "light travels faster than sound", "fish have fins", etc. All facts, it is to be noted, about our natural, phenomenal, world. So far so good! But then he continues to claim "their truth or falsity is independent of what anyone thinks about the matter" and this is untenable.

For one thing, if someone didn't think about them at some time how did they come to be established as facts to begin with? For another, the "theory-ladenness thesis", orthodox within both science and philosophy of science today (Popper, Kuhn, Lakatos, etc.), sustains that there is no judgement that we make of the world that is "independent of what anyone thinks of the matter". Facts are never objective in this way. They always proceed from a theory (what counts as a fish, for instance) because interpretation always comes between us and the world - there is no way, as we have known since Kant, that we can experience the world as it is, if this latter expression even makes sense. There is no objective reading of the world if this means stepping outside our skins, as Thomas Nagel puts it.

This does not render the claim to objectivity meaningless, we use it all the time in science and in daily life, in reporting events etc., but it means that the notion of an objectivity such as Prof. Friggieri postulates, "independent of what anyone thinks of the matter", is incoherent; theoretically that objectivity is only available to God. In science it corresponds with the demand for publicly verifiable evidence. And claims to truth made on the basis of evidence are not absolute but conditional; future evidence may turn them false. In short, scientific truths are fallible. As Imre Lakatos cryptically observes: "Before Einstein most scientists thought that Newton had deciphered God's ultimate law by proving them from the facts"; but they were wrong. So, if scientific truths are fallible what does that say about "moral truths"?

Prof. Friggieri defines objectivity in ethics as "the view that moral judgements can be true or false". This implies that moral judgements are factual judgements; like the ones he cites about light, metals, fishes, etc. So that "killing the innocent is always wrong" is true in the way that "light travels faster than sound" is true. But this is untenable because the conditions that make the latter statement true, scientific proof, are unavailable to the former.

One cannot prove the statement "killing the innocent is always wrong" scientifically. What evidence would justify it? Where would one begin to look for the evidence? There are no answers to these questions because the language of proof and evidence, though it may be that of science, is not the language of morality. Though facts help us make moral decisions, moral language itself is not factual; it is normative, a language of values, and there should be nothing controversial here.

So Prof. Friggieri must believe that moral truths are found elsewhere than in the phenomenal world and that we have some other "eye" beside our physical eye, a "mind's eye" to see them with. If he does believe this, then the discussion is closed because these beliefs are not demonstrable. The same is true if he believes them to be revealed in a divine way, which is not a matter of proof but of faith and also beyond argumentation.

Another option is that they can be read into human nature. But how? Intuition won't do because it is notoriously fallible. Perhaps they are self-evident truths and just "hit" our eye the way that the physical atural world around us hits our eye all the time. But then, perception implies judgement and, to paraphrase MacIntyre's remarks about "rights", though I may know what a fish or a piece of metal looks like, what does a moral truth look like? What is there that it is supposed objectively to correspond with the statement "killing the innocent is wrong" out there in the way that statements about light, fishes and iron are meant to correspond with physical phenomena? Perhaps they proceed from reason, but how? Which reason? Which reason is human reason?

Prof Friggieri supplements his definition of objectivity not with demonstration or argument but with rhetoric and with a long list of "intrinsically wrong" acts that nothing, he says, justifies. So what does he make of the fact that practically every one of these acts has been justified in some place and at some time in human history, and is still justified today? It should, at the very least, alert him to the fact that defining "innocence", for instance, is not like defining a fish or the speed of light. Indeed, innocence is a notoriously complicated concept, particularly in war scenarios - in the use of human shields, for example. If killing the innocent is wrong it's not because there is some fact that makes it so but because it revolts us, or some of us - we, 20th century people with our kind of moral sensitivity and our Western culture. It plainly does not revolt others and it wasn't a problem in Biblical or Classical times, nor for the numerous human cultures where the sacrifice of innocents was an accepted way of appeasing the gods.

The same can be said about torture which can take forms different from that carried out by the Holy Inquisition (which certainly didn't think it evil), more subtle perhaps, that are common today. Recently an argument was made in the United States that it should be used where the lives of innocents are at stake (in acquiring information about planned, indiscriminate suicide bombings, for instance). The argument, if one values innocent lives, is not so easily put aside. An online poll showed that the majority of Americans still find it objectionable. But another 9/11 might make them think differently.

I share his feelings about the objectionable acts he mentions but I do not know what the claim that they are "intrinsically wrong" means. For me, something is always wrong for a stateable reason, like harming people for instance. Saying that an action is "intrinsically wrong" is not giving up on reason, it is giving up on reasons, hence it is giving up on dialogue. Nor do I put our agreement down to the fact that we share some moral truth. I put it down rather to the fact that we share a moral culture. And I claim no intrinsic value for that culture or for my sentiments.

I recognise that those who perpetrate some of the acts he mentioned, suicide bombers for example, may feel as impassioned in their defence of them as he and I feel about ours. Indeed, they feel like Prof. Friggieri, and they show it by putting their lives on the line, that they have the moral truth and that people like he and I are wicked unbelievers.

My final point, and I shall end with it, is that what can help dialogue in this world of ours, if it is at all possible, is not the taking up of absolutist positions defended by a claim to "objectivity" or truth, but a Socratic understanding that we operate in ignorance and need to negotiate the truth together.