I have been maintaining that the meaning of the word 'ought' and other moral words is such that a person who uses them commits him...self thereby to a universal rule. This is the thesis of universalizability.LESSATTRIBUTION DETAIL »
It is, most fundamentally because moral judgments are universalizable that we can speak of moral thought as rational (to universal...ize is to give the reason); and their prescriptivity is very intimately connected with our freedom to form our own moral opinions (only those free to think and act need a prescriptive language).LESSATTRIBUTION DETAIL »
Our argument ... will result, not upon logic by itself--though without logic we should never have got to this point--but upon the ...fortunate contingent fact that people who would take this logically possible view, after they had really imagined themselves in the other man's position, are extremely rare.LESSATTRIBUTION DETAIL »