Most people, I suspect, would instinctively incline to the former point of view, which is why the Liberals were not entirely displeased at Mr. Layton's ad hominems, insofar as they exposed the NDP leader as a hothead. Yet Mr. Layton's comments found some support, and from some surprising quarters, among them the editorial board of the Ottawa Citizen. "No credit without blame is the very definition of responsibility," it admonished Mr. Layton's critics. "If Mr. Martin had introduced a program to reduce homelessness and homelessness had subsequently declined, he would surely take credit for it... And if the decline in homelessness had produced a drop in deaths among homeless people, Mr. Martin would be quick to claim that victory, too."

Actually it is supremely unlikely that Mr. Martin would ever claim personal responsibility for saving homeless people's lives, and if he did he would be properly roasted, for much the same reason that Mr. Layton is being roasted now: The public's moral intuition that the links between policy and its alleged consequences are too remote to permit the attribution of personal blame or credit, especially on such an inflammatory subject, with the enormous raising of the emotional stakes this implies. The Citizen's reasoning has here got the better of its judgment, as earlier Mr. Layton's emotions did his.

Mr. Layton was not merely engaged in a dispassionate discussion of cause and effect. He was in fact attempting to short-circuit just such a discussion. Listen to his choice of words: "I hold him responsible... I will not forgive him." He is not asking his listeners to assess the policy in dispute, the cuts in federal funding for social housing Mr. Martin imposed in the 1990s. He is asking them to pass judgment on Mr. Martin's morals -- and, by implication, on his. ("I hold him responsible ... I will not forgive him.")

He is probably sincere in this. But that does not make it any more acceptable, morally or logically. To blame Mr. Martin personally for the deaths of homeless people -- to accuse him, in effect, of killing them -- is to gloss over any number of intermediate steps, whether of causality or intent. It is to suggest he is guilty, if not of deliberate callousness, then of reckless disregard for the probable consequences of his actions.

Some number of homeless people died in the 1990s, as they do every year. Yet it has not been established how many of these died because they were homeless, and it is even less clear they were homeless because of Mr. Martin's cuts. Any number of other factors might have been at work in either case; some, such as the deceased's mental state, may better explain both. Indeed, it is not even clear there was any increase in death rates among the homeless population, since there are no reliable figures in this field. Mr. Layton may fervently "believe" so, but that is simply his opinion. To convict someone of murder, or even criminal negligence, as he would have us convict Mr. Martin, you need better evidence than that.

But, you protest, isn't it obvious that public policy affects people's lives, that indeed it can cost lives? Isn't that the reality of being in government, whether the subject is traffic laws, safety regulations, or health care? Small differences in policy can greatly affect the incidence of death on the nation's highways, or its hospitals. Whole academic disciplines are devoted to the study of risks and mortality rates, and the unintended consequences that can arise from various policy choices. (Example: Recent airport security measures, introduced in the name of saving lives from terrorist attacks, raise the cost of an airline ticket by a certain amount, causing a certain number of people to take the car instead, where they face a vastly greater likelihood of being killed.) What's so unusual about applying the same analysis to homelessness?

But that rather makes my point. Take that extraordinary study the Post reported on the other day, suggesting as many as 24,000 people die every year in this country due to "adverse events" -- cockups, in plain language -- in the course of being treated by our beloved public health care system. Now, critics on the right may wish to argue this is the inevitable consequence of a bureaucratic state monopoly in which the patient is often treated more or less as an afterthought. And critics on the left are free to reply that it is only because the system has been starved of the funds it needs. But the one thing that is least likely to advance the debate is if both sides haul off and bellow, red-faced, that they hold each other personally responsible for the thousands of dead, and will never forgive them for it.