When do we lie?

You tell the first lie of the day when you put your clothes on.

--unknown source

When do we lie?

The ubiquity of lying prompts the question: Why should we ever tell the truth? But while this normative inquiry may be appropriate for moral philosophy, social science is more properly concerned with answering slightly different questions: not why should but why do we so often tell the truth, and when do we not do so? For we find empirically that , in societies and cultures of great diversity, with their distinctive codes of religion and ethics, the truth is told more often than not.

In warfare lies are taken for granted: in politics lying may be perceived as frequent, but occurs in the face of protests and is regretted; in bureaucracies protective lying is legitimate but other kinds of lies are not; academics usually assume that references, favourable and unfavourable alike, have been written in good faith even when doubting their validity. When people move from one domain to another, they may have to adjust their expectations of the truthfulness of others, as well as their own level of truthfulness.

--J. A. Barnes.