Skepticism usually involves telling someone that they may not be correct.
As such, skepticism can be sometimes regarded as negative, even aggressive or condescending.
This can certainly be the view of those whose dangerous certainties, from religious enthusiasts to promoters of alternative health remedies, are most at jeopardy from scrutiny and the demand for evidence.
The Amazing Meetings - or TAMs for short - show skepticism and critical thinking in their true and far more positive forms. And yesterday was the first day of TAM London 2009, the first TAM to be held outside the United States.
There were many highlights from a day when every single speaker and act was in very top form.
Professor Brian Cox described the importance of curiosity-based science.
For me, as a still-partly-cynical-ex-Tory, this curiosity-based science could mean a cunning way of diverting scarce money from taxpayers to inconsequential academic hobbyists. But Professor Cox took this argument face on.
And he did so in a most effective way.
He started with an actual example of woeful management-speak, a ghastly powerpoint presentation of some science funding body, where the "Wow factor" was listed on some depressing slide as an afterthought bulletpoint.
He then contrasted that slide with remarkable photographs of the Earth from Space, and - from Hubble - of Space from Earth: all of which prompt a Wow factor that a mere bulletpoint could never achieve.
Professor Cox then matched this wonder with a quote from (the indeed arch-conservative) TS Eliot:
We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time.
To understand as well as we can our place in the universe is a great and intellectually-liberating aim. As I watched, I could almost feel remnants of my naysaying Toryism falling away.
Of course there is the issue of how we organise our scarce resources, where other priorities can be more immediate, but the point that there should be publicly-funded curiosity-based science is compelling.
I may well have been a conference hall full of skeptics, but I don't think I have ever felt less cynical.
This emphasis on being constructive was shared, but in a markedly different way, by another speaker, the journalist and campaigner Ariane Sherine.
She is a heroine of mine, for converting a couple of newspaper columns in to the entire Atheist Bus Campaign.
This campaign was a moment when atheism ceased to be intellectual honesty that dare not speak its name, and in a breezy and cheerful way became part of the nation's general conversation.
Atheism, of course, is not exactly the same as skepticism. A skeptic must, one supposes, admit the possibility of any truth, however bizarre, even the possibility of a god.
The Atheist Bus Campaign sought to make people reconsider their views on this ultimate question, by showing there is another and life-enhancing side to the debate.
The greatest highlight for me was Simon Singh being presented with the James Randi Award for Outstanding Contribution to Skepticism, UK, mainly for his defence in the current libel case.
In someways, it was a strange award for skeptics to give: for so far Simon has lost a preliminary hearing in the High Court, and it really isn't very difficult to be the losing party in any litigation.
Anyone can do that.
However, Simon has used the misconceived libel case brought by the now discredited British Chiropractic Association to force major debates on two extremely important topics: the actual evidence bases for alternative medicine, and the repressive effect of English libel law on the public's access to critical information.
To take a difficult legal case and to use it to generate not one but two public debates is a simply astonishing achievement. And to do so by standing firm, and by not being intimidated by the costs and demands of fighting an English libel case, and to keep smiling, is to make this achievement also a moral example of the very first order.
And Simon used his acceptance speech to make the happy announcement that he was to become a father.
(If it is a boy, I have suggested David as a name, as it may just impress Sir David Eady, and so could well be Simon's best chance.)
Overall, TAM London demostrated that skepticism and critical thinking can be engaging, inspiring, and deeply practical.
In different ways, Brian Cox, Ariane Sherine, and Simon Singh, as well as all the other speakers and acts at TAM, were explaining and showing the value of pure inquiry and the search for evidence, and the value of contributing to and indeed creating debates where there can otherwise be easy and dangerous certainties.
It was indeed an amazing meeting.