Ideas matter; they shape the fate of individuals and the destiny of nations. Take John Howard’s alternative reason for the Iraq War – the ‘US alliance’; it invokes an idea underlying a long history of discretionary wars fought for imperial, colonial and ‘balance of powers’ aims. But it denies the central idea of international law that the use of violence to advance national interests is wrong; it ignores the difference between interests and values, which Kant saw as the basis of all moral reasoning.

What ideas prompted the Liberal party’s refusal to apologise and it’s about face when Howard was replaced by Brendan Nelson? To answer this we need to look at two assertions Howard relied on; first, those responsible did what they thought best by the standards of the time; secondly, a government is not responsible for the wrongs of its predecessors.

The first claim challenges an important distinction in general philosophy and in ordinary, everyday argument on social and political matters; this is the difference between an excuse and a justification. While the terminology is familiar, the difference is easily blurred. Acting in good faith is always an excuse; it negates or reduces blame for wrongful acts and, in a legal system, is a mitigating factor in punishment.

But an excuse which mitigates blame is not the same as a justification – it does not mean the conduct in question was not wrong. This is clear in a legal system where the rules are ‘objective’ – they exist independently of whether we are aware of, or support them. So it is easy to see how an act can be illegal even if most people, even lawyers, think otherwise; there is a difference between what we think is a legal duty and what, according to the law, is. In such a case we might agree someone committed a legal wrong even if they are not to blame.

Does this make sense in moral reasoning? It was ignored by Howard when he said no apology was needed because officials did what they thought best. But is this right? Is the fact that they acted in good faith according to prevailing practice proof that no wrong was done, or do we say an apology is called for because – whether through ignorance, prejudice, or failure of moral imagination – they committed a terrible wrong despite their intentions? And if we apologise does this mean we think morality, like law, is in some sense objective?

Clearly the claim that officials, government or the community were mistaken in their moral judgment must presuppose standards against which such a claim can be tested, but does it require the abstract values – values such as humanity, justice and human dignity – which describe these standards to be ‘objective’ and what, in any case, would this mean?

It is not hard to see what it means for a form of scepticism – often described as ‘positivism’ – which holds that for judgments about moral duties to be intelligible it must be possible to validate them. That test is satisfied when courts exercise authority to interpret laws defining legal duties. It is satisfied when religions settle doctrinal disputes by appeal to a sacred text or ‘book of rules’, interpreted by a leader or council of elders – it gives finality to disputes just as judges give clarity to the law. This satisfies philosophical sceptics because there is an objective test – contraception is a sin if the Pope has formally so ruled, or if a Vatican Council has so pronounced.

If, however, we are arguing about the requirement of values such as honesty, fairness, justice, liberty, compassion, humanity, benevolence, human dignity, and so forth – which is what most social and political debate is about – there is no procedure to validate judgments and no agreed person or body of persons with authority to settle disputes. This leads the hard-core moral sceptic – often a disappointed absolutist – to conclude that there is no such thing as truth in matters of social and political morality; there is only the shifting sands of opinions, likely to reflect a range of interests, preferences, religious beliefs, philosophical theories etc.

This brief detour poses a question: How could someone with Howard’s impressive political intelligence fail to see that just because past officials did what they thought best did not mean they committed no wrong and no abuse of basic rights? Is it possible that – at least in his political philosophy – there is no real commitment to those values of humanity and fairness which have led most people, including nearly all his colleagues, to support the apology? Is it possible for a devout Christian and decent family man to be a moral sceptic in the above, philosophical, sense?

However that may be, the most interesting challenge to the sceptic’s account is the idea that morality, like law, is an interpretive practice such that truth resides in the best interpretation and the arguments which support it, a thesis developed over the past half-century by the late Ronald Dworkin, first in a series of brilliant jurisprudential essays and books culminating in his Law’s Empire in 1986 and, two years before he died, in an acclaimed and original work on the nature of moral reasoning titled – after a famous essay by Isaiah Berlin – Justice for Hedgehogs.

At the heart of Dworkin’s theory is a simple yet profound idea: the morality of a community is found, not in its opinions on moral issues, but in the best interpretation of its values. The theory has critical power as well as explanatory force; it meshes with some famous insights on the nature of moral duty, including Kant’s ideas on autonomy and universalizability, as well as Burke’s view that politicians must, above all, act on conscience. There is no space here to expand on the thesis, other than to suggest its importance, if correct, for the philosophy of the social sciences.

Howard’s second assertion, that a government is not responsible for the wrongs of its predecessors, can be dealt with briefly because it is a denial of the idea – which underlies both international law and domestic constitutional law – that the nation, as a political entity, is responsible for what its governments do in their relations with other nations as well as their own citizens – governments are agents of and for their political communities.

Finally, one reason for the Liberal Party’s refusal to apologise may be a reluctance to accept that good people with bad ideas do terrible things; there is, in fact, a good case that the concept of evil, as generally understood, works to deny this truth. However that may be, the difference between an excuse and a justification is important because, if those perplexed by the Iraq War and refusal to apologise think such decisions cannot be immoral unless those responsible are evil persons, they will never understand the role of values as moral standards.