Sir William Beveridge identified what he called five “Giant Evils” in society in his 1942 report on “Social Insurance and Allied Services”.

And to address these – squalor, ignorance, want, idleness and disease – he proposed ambitious reforms that came to be known as the “Welfare State”, chiefly an expansion of National Insurance and the creation of a National Health Service.

And while that Welfare State still exists intact more than seven decades after Beveridge’s conception, at some point every UK government has had to balance a belief in maintaining that safety net with the logistical reality that it involves spending an awful lot of money.

Attempts to alter that balance are inevitably controversial, with opponents depicting every reform as a “cut”, every attempt to recalibrate the Welfare State as its “destruction”. Mrs Thatcher, we’re often told, “destroyed” it in the 1980s, followed by Tony Blair in the 2000s and now David Cameron. It’s endured an awful lot of destruction.

Such hyperbole precludes rational debate, and the ongoing row about cuts to tax credits is no exception. Today the House of Lords will stretch constitutional propriety by defying the Lower House on a financial matter, while tomorrow the Commons will consider the Welfare Reform and Work Bill’s Report Stage. Yesterday Scottish Conservative leader Ruth Davidson added her voice to those urging a rethink.

And while it’s been interesting to watch the SNP defend a key policy of the Blair era, the party’s Westminster group have been consistent and often eloquent opponents of the UK Government’s plans, scrutinising the legislation and highlighted its iniquities; they have done what a good opposition party ought to do.

That, however, is the easy bit – opposing Tory cuts comes easily to the SNP – setting out an alternative, and not just when it comes to tax credits, is much harder. Now for a long time the Scottish Government has been able to get off that uncomfortable hook for it lacked any meaningful powers over welfare, but not for much longer.

As a result there’s been an interesting shift in Nationalist rhetoric. Asked recently if he would reverse £6 billion in benefit cuts, Finance Secretary John Swinney said it was “highly unlikely”, while last week Ian Blackford MP said it was “completely unrealistic” to expect Scotland to plug the “black-hole” created by the UK Government’s cuts to tax credits.

But why is it “completely unrealistic”, particularly given ministers have done precisely that in relation to the “bedroom tax” and changes to Council Tax benefit? Furthermore, Scottish Secretary David Mundell has made it clear the current Scotland Bill will not only enable ministers in Edinburgh to “top up” existing benefits, but also introduce payments for those in “short-term need” and even “design new benefits” alongside full control over income tax.

But, cry Nationalist MPs and MSPs, this is a Tory “trap”, for it’s attempting to force the Scottish Government to raise taxes in order to pay for more generous welfare, thus making itself less popular electorally. This, however, has long struck me as a curious argument: a party that desires full responsibility (i.e. independence) arguing greater responsibility over tax and welfare amounts to a “trap”.

Thus the SNP is generally giving the impression it’s powerless to do anything. In a Commons debate on tax credits last week Mr Blackford implored the UK Government to give the Scottish Government power over welfare so it could “protect people in Scotland” from Tory “damage”, while, asked by Conservative MP Chris Philp if she supported using the new Scottish rate of income tax to increase tax credits, Mhairi Black simply said tax credits would remain reserved and ducked the point about income tax.

The SNP’s defensiveness when challenged in this way reveals much about its views of wealth redistribution (generally against) and broader philosophy of welfare (generally half-baked). On the latter point, John Swinney merely says his party aims to put in place an “affordable” welfare system based on what it “inherits” when Scotland became an independent country.

Not only does that sound very convenient (it might “inherit” something quite modest if the Chancellor has his way), it’s vague to the point of being meaningless. Social Justice Secretary Alex Neil’s recent paper, “Creating a fairer Scotland”, isn’t much better. A prelude to another document in December on the SNP’s “vision” for a “Scottish approach to social security”, that “vision” doesn’t extend much beyond possessing a set of “principles and values”.

Basically the challenge boils down to this: does the Scottish Government see itself as a mitigating or genuinely reforming administration? As this column has previously argued in relation to local and national taxation, the SNP ought to view its new powers and Tory reform plans as an opportunity rather than a threat. George Osborne seems committed to redesigning the UK state as he prepares to become Prime Minister, so why can’t ministers in Edinburgh think in similarly bold terms?

Instead they often devote an inordinate amount of time to explaining why they can’t use their new powers and why they can’t put their fiscal levers where their mouths so often are.

Glasgow Shetteleston MSP John Mason was a lone voice at the SNP conference in actually urging his party to go into the next election on a tax-raising platform, though he’ll be acutely aware he’s in a minority.

Part of the trouble, I suspect, is public opinion. A recent opinion poll confirmed what most other surveys of Scottish public opinion have shown for quite some time, in other words a small “c” conservative approach to tax and spend. While 52 per cent of Scots would support tax increases if it meant better public services, 60 per cent didn’t believe Holyrood should use its new income tax powers to fund a more generous welfare state.

And given the SNP’s commitment to “standing up for the values, interests and aspirations of mainstream Scotland” (Nicola Sturgeon’s phrase, not mine), this puts the party in a self-evidently difficult position. If, in other words, the First Minister believed “mainstream Scotland” was up for a generous recasting of the Welfare State then she’d legislate tomorrow.

Instead the SNP leader included a trademark announcement in her conference speech, a modest but symbolic commitment to increase the Carers’ Allowance so it’s paid at the same level as Jobseekers’ Allowance when her government “gets the power to do so”. That the Scottish Conservatives had already announced such a policy illustrated just how cautious the First Minister was being.

But bold reform can pay off. If the recent Audit Scotland report on the health of the NHS demonstrates anything it’s that: populist opposition to politically difficult reforms (not to mention nostalgic attachment to “universal” provision) might work in the short term, but in the long term it generally brings trouble. Independent or not, the Scottish population is a demographic time bomb that requires urgent defusing.

It took Sir William Beveridge’s committee more than 18 months to outline the shape of government policy for the next seven decades; the Scottish Government has about six months.