For Popper, then, ideological thinking should be opposed tocientific theorising which always produces falsifiable hypotheses. A
cientific approach to social matters consists in developing piecemeal
explanations about how things work and testing them out — not in
having a grand theory that explains everything. The validity of
Scientific propositions (which are falsifiable) can be agreed upon by
any two persons of good will in the light of the current evidence and
are subject to modification in the light of new evidence. To make
political judgements, however, people must also employ judgements
about values, which are specific to them and cannot be resolved by
looking at evidence. Political innovation therefore depends upon
building consensus about values between the people concerned as
well as correctly interpreting cause and effect. Consequently rather
than building some grand Utopia on the basis of first principles, social
change should proceed by means of ’piece-"meal social engineering’