"I did not have sexual relations with that woman, Miss Lewinsky."
Bill Clinton, January 26, 2003.

If you think Bill Clinton’s statement at a White House conference about his
relationship with Monica Lewinsky was just a bare-faced lie, consider this.
In some circumstances, it is desirable for young people to maintain that they
are still virgins. In others, it would be a complete embarrassment.

Take a seventeen-year-old boy from a conservative family who has experience
of oral sex, mutual masturbation and so on, but not penetrative sex. "Are
you a virgin?" asks his parents. "Yes," the boy replies. "Are
you a virgin?" ask his friends, "Dur, no!" comes the reply. Wouldn’t
you say that in both cases the boy is being at the very least a little disingenuous?
Yet one of the answers must be true.

When Clinton looked straight into the camera and said he had not had sexual
relations with Monica Lewinsky, he was talking as the boy was to his parents.
He chose to interpret "sexual relations" as being a euphemism for
full sexual intercourse in a context where the people asking the questions want
to know about sexual behaviour more generally. He was playing on the ambiguity
of the term to state a half-truth, which I would define as a statement which
can be read as being literally true, but which occludes other important relevant
truths.

In that case, the half-truth was seen through pretty quickly. But what about
this statement from Tony Blair to the British parliament on 24 September 2002?

It [the UK intelligence dossier] concludes that Iraq has chemical and biological
weapons, that Saddam has continued to produce them, that he has existing and
active military plans for the use of chemical and biological weapons, which
could be activated within 45 minutes, including against his own Shia population;
and that he is actively trying to acquire nuclear weapons capability.

The British government and Tony Blair have vigorously defended the truth of
the notorious 45 minute claim, or at least that it was an accurate statement
about what British intelligence thought at the time. But as I define it, this
looks very much like a half-truth. The kinds of weapons which could be activated
in 45 minutes were relatively small battlefield ones and not the "weapons
of mass destruction" which had dominated debate. Indeed, this is what the
Intelligence and Security Committee, comprising members of parliament, concluded
in its report, which exonerated Blair of the charge of lying, but said:

As the 45 minutes claim was new to its readers, the context of the intelligence
and any assessment needed to be explained. The fact that it was assessed to
refer to battlefield chemical and biological munitions and their movement
on the battlefield, not to any other form of chemical or biological attack,
should have been highlighted in the dossier. The omission of the context and
assessment allowed speculation as to its exact meaning. This was unhelpful
to an understanding of this issue.

Half-truths exploit the difference between telling a lie and not telling the
truth. One can fail to tell the truth by not saying everything as well as by
saying things that are false. But the idea that lies are of necessity ethically
worse than half-truths is hard to defend. Indeed, given that it is not always
wrong to tell a lie (as in the hackneyed example of lying to protect an innocent
person from a potential killer) it seems what is crucial is intent and effect.
And the effect and intent of a half-truth can be as good or bad, malicious or
honourable, as a lie.

Rhetorically, however, half-truths can be more powerful than lies. Because
half-truths are nonetheless truths, credible evidence can be given to support
them. They can also be stated with total sincerity and conviction, just as long
as the utterer is able to convince herself that, not being lies, they are really
ok. But half-truths are designed to deceive, to deflect our attention from what
hasn’t been said but which is of crucial importance. They are no better than
lies and can sometimes be worse.