The metaphor itself is so striking that it leads to confusion, giving a sense of momentum and inexorability which are not necessarily there.
Contrast the issue with the metaphor of a swamp. It does not follow that if you enter a dirty smelly swamp and get dirty and smelly you are doomed to stagger on into the middle and sink without trace.
Second, I do think as a lawyer and a diplomat who has operated on the edges of some of the greatest moral issues of our time (Communism and Apartheid) that part of the drama of government is not so much a slippery slope as a continuum. Most issues are like that, one point shading into another and another and so on. Yet although it is impossible to say definitively at what point white turns into black along a colour spectrum, white and black are different.
So there is some sort of continuum between the force used in arresting people and threatening them with the stress and likely violence which comes from many years of prison, and at the far end outright torture. Both may have the same purpose – to extract information using violence or the threat of violence. Yet it does not seem right to say that we should not arrest people and confront them with the prospect of prison because that would put us on the Slippery Slope to torture.
So the operational policy point for decent policy makers and the people who have to implement the ensuing laws and policies – sometimes under ghastly circumstances – is indeed all about drawing distinctions somewhere along these many continuums (continua?) in a way which is morally defensible, all things considered.
This is a huge and unmanageable subject, since to add to the numerous implications (implicit and explicit) of the metaphor itself (simplified beyond recognition by John, to help him make his case?) must be the reasonable facts of each case – how might one slide down this particular SS, how steep is it, how great the crash at the bottom, and so on.
And it all depends too on what exactly you are suggesting by the metaphor and the similar ‘thin end of the wedge’ metaphor.
Is it that by accepting A you logically have to accept B and C and so on?
Or rather that if you accept A it is very likely (or quite likely, or more likely than not) that in practice you’ll end up getting B and C and so on, even if these results logically and in policy terms can be distinguished?
Liam is more right than wrong, and John more wrong than right.
This is not a Left/Right conservative/liberal point at all. Both tendencies use these arguments for their own ideas or against the ideas of others as and when it suits them.
In the case cited by John, the Obamacare reforms, opponents of these changes surely have a good SS-style point on their side when they point to the likelihood of costs escalating and savings being far less than advertised. That seems to happen with almost any government activity you can think of. In other words, they are concerned that if they accept A then as a matter of how things work they will get B and some C, with the costs of all of them soaring. Plenty of experts are saying just that.
A rather different SS-style argument is the one which says that as a matter of political and legal logic, the way the reforms are drafted opens the way to federal-funded abortions or eventual state-run rationing of drugs and treatments. That too is a non-trivial outcomes claim. See examples of state-run health systems everywhere else.
Supporters of the reforms have to take such arguments seriously, partly because the arguments are serious and partly because voters are impressed by them.
There are of course lots of different arguments against these positions:
the current system has to be fixed
in fact the new deal will work well and to budget for x/y/z reasons
we are alert to the risks you describe and have built in p/q/r to deal with them
Maybe those will be convincing, maybe not.
Basically, the whole point of metaphors is to convey complex ideas in folksy language.
Everyone does it. But let’s not get carried away and try to pretend that one political tendency is more prone to using alarmist metaphors than the other.
Above all, remember that a metaphor is a metaphor.
And that other metaphors may describe the issues and underlying assumptions much more clearly and helpfully.