A recent Wall Street Journal editorial sobbed as it put the old mare to sleep. ''The intellectual influence of monetarism has been waning,'' it noted, but if economic thought has evolved ''beyond the monetarism of recent years, it is an evolution in which the monetarists played an absolutely crucial role for which they will long be honored.''

The Economist weekly, as is its way, was more brisk. ''The year monetarism dies?'' it asked, ghoulishly, as 1986 began.

It is not so much monetarist objectives that have fallen into disrepute, as it is the particular means by which they are to be achieved: that is, of targeting particular measures of the money supply as a means of controlling economic activity. This certainly appears to be the thinking at the Bank of Canada. Whether the reports of monetarism's death prove greatly exaggerated will depend on whether this technical problem can be overcome.

The central core of monetarist thought, as mentioned, remains firmly lodged in the mainstream of economics, and can be summarized as follows:

The growth of total output in dollar terms (''nominal GNP'') is determined by the interaction of the supply and demand for money. Since the demand for money tends, over time, to follow a predictable path, governments may control the growth of nominal GNP by an appropriate regulation of the money supply.

Increases in the money supply cannot, however, alter the economy's real productive potential. While monetary stimulus may for a time push real growth above that potential, eventually it affects only prices.

The money supply should therefore increase only enough to accommodate growth in potential output, but since that is difficult to gauge, and since money increases take effect with unpredictable lags, monetary policy will do least harm by keeping money growth on some fixed rate.

More than that, recent theory stresses, it should be seen to be fixed: if economic players know what the central bank is up to, their actions and expectations of inflation will adjust more readily; inflation will come down more rapidly, and with less drop in output. Central banks should therefore set explicit, well- advertised monetary targets. The closer the authority hews to the monetary rule it sets for itself, the less will output deviate from trend.

This is where the difficulty starts. What Western countries attempting to apply monetarist prescriptions have discovered is that the accelerating pace of innovation in financial markets has given the public many new ways to hold money. This has blurred the distinction between different measures of the money supply, as individuals and businesses shift into and out of financial assets, and has made individual measures increasingly meaningless as indicators of overall monetary conditions.

The example of the Bank of Canada is instructive. Most people will recall that Bank of Canada Governor Gerald Bouey introduced monetary targeting to the Canadian scene in 1975, picking M1 - currency plus noninterest bearing chequing accounts - as the money supply that mattered.

In the early years of setting ranges for M1 growth, the money supply came in more or less on target, and its relationship with total spending in the economy remained more or less predictable.

In 1981-82, however, things began to go very wrong. The relationship between the money supply and output and prices became far less certain. While the growth rate of M1 dropped off alarmingly, nominal GNP did not trace a similar path (see chart).

What caused this decoupling was a substantial drop in the demand for M1. This was largely due to the introduction in 1982 of daily interest chequing accounts, which attracted a growing portion of funds away from ordinary chequing accounts, and increasingly from savings deposits.

Other banking innovations allowed corporations to pursue more aggressive cash management techniques, collecting all their excess transactions balances together at the end of the day, for instance, and lumping them in interest-bearing notice deposits.

The upshot was that a given amount of M1 supported a higher level of total spending, or in other words, its velocity increased - not, as had been the case during the years of accelerating inflation in the late 1970s, along a predictable trendline, but at a markedly greater pace.

At which point, the Bank of Canada threw up its hands. Rather than adjusting the target, or possibly using a different money measure, the Bank, in November, 1982, gave up targeting altogether. Despite assurances at the time, it has shown no signs of returning to the practice: Bouey's annual report, issued last month, makes no mention of targets.

The result has been the destruction of any semblance of a stable expectational climate. It is today very difficult to tell what the Bank's current monetary policy is. Rules are out; ad hocery is in. Says University of Western Ontario Professor David Laidler: ''They appear to be looking at everything from week to week and not telling anybody what they're doing.'' This uncertainty was surely a factor in the run on the C$ in 1985-86, since there was no guarantee that Canada's deficit burden would not be relieved by monetization.

What's a central bank to do? A recent issue of the Bank of Canada Review, surveying developments in monetary aggregates over the past few years, speaks glowingly of the performance of M2 as an indicator, which suggests the Bank is at least giving it increased prominence in its thinking.

There is good reason for this: since M2 encompasses currency, ordinary chequing accounts, and interest-bearing chequing and savings accounts, shifts between each component will not affect its overall level. A broader measure, M2+, which includes deposits at the increasingly important nonbank financial institutions, performs even better as an indicator.

Whether M2, M2+, or any of the 43 other measures the Bank's research department has devised are guiding Bank policy, however, without a more forthright public declaration of fealty to some monetary rule, the Bank's commitment to price stability lacks credibility. Further lasting progress against inflation, therefore, will come at a greater cost than necessary in forgone output and employment.

A return to an explicitly rule-based monetary policy need not involve rigid numerical targets. A monetary rule which has repeatedly to be broken causes more uncertainty than no rule at all. Rather, a ''velocity-adjusted'' monetary rule might be set, indicating not only how much the favored monetary aggregate would be permitted to grow over time, but exactly how the central bank would adjust the target in response to a given change in money demand.

This would not entail a return to ''fine-tuning.'' Monetary policy would still be attached to a nominal target, not, as was the great mistake of the 1960s and 1970s, to a real magnitude like output or employment. Nor indeed would transitory shifts in velocity require a change in policy, since velocity in the short run can jump about for reasons unrelated to any change in money demand. But permanent shifts in trend velocity for a chosen aggregate would have well- advertised, predictable policy implications.

The logical extension of this might be to look through the intermediate monetary targets and simply target nominal GNP directly, since, by the great monetarist equation MV=PT (Money times Velocity equals Price times Transactions) that is nothing more than Money times Velocity. This was a recommendation of the Macdonald commission, and has recently reached semi- official status in British monetary policy.

The difficulty with this is that accurate data on total spending are not available until considerably after the fact. Add to that the lag between a policy shift and its taking effect, and you have a delay of perhaps two years between whatever money demand ''shock'' the authorities wish to counteract and the economy's eventual policy-induced response. Nominal GNP is hence hardly less difficult to hit than a monetary aggregate target, nor is it any more likely to be credible with the public.

The case could therefore be made that central banks should stick with targets more directly amenable to their control. It is, in any case, ''an argument between friends,'' as Laidler says. For those who believe price stability is an essential precondition for full employment, the particular choice of strategy is less important than the continuation of the fight against inflation.