A speech for the defence in a Paris murder trial, a road-safety slogan, Hobbes' political theory; each appeals to reason of a kind, but it remains an oblique and rhetoricalldnd. Each relies on comparisons rather than on direct statements, and none can override or supersede the conclusions of ethical reasoning proper. Nevertheless, just as slogans may do more for road safety than the mere recital of accident statistics, or of the evidence given at...