evidence and ideology

Evidence and Ideology

Nancy Cartwright

From drug laws to terror threats, we want political decisions to reflect the facts. But is objective evidence impossible and the facts ours to interpret? Philosopher Nancy Cartwright investigates.

  • Nancy Cartwright

    Former mathematician, now professor of philosophy at California and Durham universities. Author of Evidence Based Policy and How The Laws of Physics Lie.


About the Course

What does it mean to base policies on evidence rather than ideology? Can we ever truly discover what works? From natural experiments to randomised control trials, philosopher Nancy Cartwright explores the murky side of evidence-based policy.

Evidence-based policy is now big business. Everything from nutrition in the developing world to cutting-edge medical treatment is now the object of randomised control trials, the so-called gold standard of scientific decision-making.

In this two-part course, Nancy Cartwright explains the mechanics of evidence-based policy and argues that our current approach is hopelessly naïve. In our rush to create a science of decision-making, we’ve forgotten to ask important questions about who policy serves, how it translates to the real world and what our real aims are.

By the end of this course, you will have learned:

  • Why determining ‘what works’ isn’t as simple as it seems
  • How efficacious policies differ from effective policies
  • Why neglected questions in policy-making are so important
  • Why representative samples are never truly representative
  • Why context is so important in randomised control trials
  • Why the system-approach to error is superior to the person-centred approach


As part of the course there are in-video quiz questions to consolidate your learning, discussion boards to have your say and an end-of-course assessment set by Professor Cartwright.

About the Instructor

  • Nancy Cartwright

    A former mathematician turned philosopher of science, Cartwright’s book How The Laws of Physics Lie has provoked continuing and internationally-cited debate.


Course Syllabus

  • Part One: Fact and Fiction
    Is evidence-based policy an impossible dream? How should decisions be made in the face of uncertainty?
  • Part Two: Changing the World
    Current practice fails to turn lab findings into real world change. Cartwright outlines her alternative.

Suggested Further Readings

Bourdieu, Pierre. The Logic of Practice. Cambridge: Polity Press. 1990

Cartwright, Nancy. and Hardie, Jeremy. Evidence-Based Policy: A Practical Guide to Doing It Better. Oxford: Oxford University Press, 2012.

Cartwright, Nancy D. 'Knowing What We Are Talking About: Why Evidence Doesn't Always Travel'. Evidence & Policy: A Journal of Research, Debate and Practice, Volume 9, Number 1, January 2013, pp. 97-112 (16).

Cartwright, Nancy D. 'Will this Policy work for You? Predicting Effectiveness Better: How Philosophy Helps'. Philosophy of Science, 79 (5) pp. 973-989, 2012.

Cooper, Harris, Hedges, Larry V. and Valentine, Jeffrey. C., ed., The Handbook of Research Synthesis and Meta-Analysis, Second Edition. New York: Russell Sage Foundation, 2009.

Cravo,Túlio A. and Piza, Caio. ‘The Impacts of Business Support Services for Small and Medium Enterprises on Firm Performance in Low-and Middle-Income Countries: A Systematic Review’. International Development, 2016.

Giddens, Anthony. and Griffiths, Simon. Sociology, Eighth Edition. Cambridge: Polity. 2017.

Seckinelgin, Hackin. International Security, Conflict and Gender: ‘HIV is another war. London: Routledge, 2014.