I can see furious shaking of heads on both sides of the political spectrum - but please read on and let me explain.
Margaret Thatcher was an outsider. A woman in the man's world of politics. A person of relatively humble origins (her father was a greengrocer from Grantham) in a Conservative Party dominated by the Old School Tie (especially the Old Etonian one). Jeremy Corbyn belongs to a group increasingly marginalized in the modern, youth-obsessed world: he is 68. Until recently, he was very unpopular with large sections of his own party.
Both were/are radicals. Corbyn's radicalism is perhaps of a traditional kind: he has spent his political life on the far left of the party, and has the badges to prove it. Thatcher's radicalism was more novel. Her ideas were based on new thinking on economics and politics: her intellectual mentor Sir Keith Joseph only began outlining his 'neo-Liberal' programme in 1974, a year before she became party leader.
Both share a sense of extraordinary momentum, from being slightly risible figures at one moment to being taken very seriously indeed the next.
Above all, both are experiencing this against the collapse of an old political and intellectual paradigm. Please don't groan at the use of the much overused p-word. I mean it in the proper, original sense used by the philosopher Thomas Kuhn in his book The Structure of Scientific Revolutions. A paradigm is a set of ideas and a programme of experiments (in politics, a programme of policies). At its core is a small knot of unquestioned, unquestionable beliefs. Around these, a collection of practical interpretations is continuously developed. These interpretations usually work, making the paradigm look a progressive, useful one. However they don't always. When an attempt to put the core ideas into practice goes wrong, the core is not questioned: instead the interpretation is revisited - what do we make of this 'not working', in the light of what we passionately believe to be true?
Over time, of course, paradigms do decay, as attempts to put them into practice fail ever more grimly. But they don't get replaced until something better comes along. A favourite example for philosophers of science is earth-centred Ptolemaic astronomy, which was used for centuries, growing ever more complex, ad hoc and bizarre, until Copernicus came along with his totally new, heliocentric model.
Margaret Thatcher rose to power against the collapse of an old political paradigm: traditional Socialism (which, in case anyone thinks I am 'against' it in some absolute sense, was itself a massive and marvellous energy-liberator in its day). Old Socialism taught that the State was for the public good (contrasted with private self-interest), and that money could always be pumped into an economy to revive it. It gave power to the Trades Union movement, which as the 1970s drew on, got ever more control over national decision-making. It had its own views on where national energy lay - in its working class - and where the barriers to that energy lay (its old ruling class and the rules they had made).
But by the late 1970s, this model was falling apart. The continuing industrial unrest of the 1970s benefited nobody. This hit its high point in the 'Winter of Discontent' in 1978/9. Irresponsible 'wildcat' strikes led to rubbish filling the streets, bodies lying unburied, hospitals being picketed by ancillary workers...
Margaret Thatcher emerged from this mess with a simple message. No more tinkering. A new paradigm is needed. In my view, she was, for all her many many faults, right.
Fast forward the best part of four decades, and we seem to be in another mess. This time, it's not Socialism that has caused it, but neo-Liberalism.
Hang on; didn't I just say that neo-Liberalism rescued us in the early 1980s?
That's what happens to paradigms. The new one rides in to the rescue, pushing some of the unworthy mighty (like Trades Union bosses) off their seats and liberating the energies of many ordinary people (a new generation of entrepreneurs). But slowly it begins to clog up with its own shortcomings. All paradigms claim to have 'the answer'; none of them do, as reality is always more complex. As time goes on, the great new ideas harden into unquestioned 'certainties'. The market is always right. It's cool to be rich and beautiful. New unworthies (like billionaire hedge fund managers or media moguls) hoard resources and power. Ordinary people are hemmed in by new constraints (zero-hours contracts and unaffordable housing)...
The wheels effectively fell off the neo-Liberal paradigm in the late 'noughties', with the near collapse of the banking system under the weight of its myopia and greed. The paradigm has lumbered along ever since, not because it is inherently right, but because no valid alternative has been on offer.
But now, along comes an outsider with a new message, just as Margaret Thatcher did in the late 1970s...
Personally, I wonder if Jeremy Corbyn is offering enough novelty. Much of his manifesto did feel like a return to the 1970s. But his message that the market is not infallible, that excessive disparity of wealth is an evil and that the State has a central role in sorting these problems, has struck a deep chord. I am hoping that a more original thinker is waiting somewhere, to turn these into a genuinely new model - one that will keep the best of the old one (the energy and creativity of an entrepreneurial culture; the value of personal freedom) and add a new positive role for a State that looks after everyone's interest, not just the interests of those who know how to play the 'free market' game.
We live in interesting times!