Tell me that somebody stopped the war

An interesting point of clash between Daniel "dsquared" Davies and Chris "Stumbling & Mumbling" Dillow lies in their attitude to Tony Blair and the Iraq War, Chris says:

Those protestors outside the Chilcot enquiry on Friday [...] accuse Blair of lying, as if this is a bad thing. Surely, what matters is the allegation that the war was a bad idea badly executed. This stands or falls independently of the question of Blair’s honesty.
Instead, there seems to be a huge premium upon sincerity; Blair himself exploited this when he famously claimed that he was “a pretty straight kind of guy.”

Daniel Davies, in his classic "One Minute MBA" argues that when a project needs to be lied about in order to get it implemented, that is a fairly strong indicator that the project is a bad one:

Good ideas do not need lots of lies told about them in order to gain public acceptance.

So I'm not sure Chris' point about the overvaluation of sincerity stands. Sincerity is generally valuable in political leaders (perhaps because it is so rare?). So those protesters were accusing Blair of lying, because lying by politicians is a bad thing, and (as Iraq shows) a potentially very destructive thing.

But this raises an interesting question: are there circumstances under which it is *necessary and advisable* for political leaders to tell lies?

I would be inclined to say that there never are. Things can justifiably be kept *secret* because the state is often privy to information that could, if broadcast, breach the individual privacy[1] of private citizens, or cause negative effects like mass panic, or even undermine the efficacy of policy (e.g. interest rate changes), but when it comes to actually broadcasting data that governments know to be false, I can't see any justification that isn't based around the interests of the individuals that make up states and governments, rather than the interests of society as a whole.

So pointing out that Blair lied[2] is in fact very relevant to the allegation that the war was a bad idea badly executed.

[1]: I would say the state as an entity should have no right to privacy, as it is not a person.

[2]: On which subject, Davies notes that:

"the difference between "making a definite single false claim with provable intent to deceive" and "creating a very false impression and allowing it to remain without correcting it" is not one that you should rely upon to keep you out of jail."