Scientific Method Limitations

The scientific method has a number of limitations including:

• Constrained by the extent of existing knowledge - Developing a hypothesis and designing an experiment is based on current human  knowledge. However, until viruses were discovered many diseases could not be explained e.g. smallpox.
   
• Design of experiment is limited to observation method and instrument -  e.g. discovery of viruses depended on the discovery of the electron microscope.
   
• Human error - e.g. mistakes can occur in recording observations or inaccurate use of measuring instrument.
   
• Deliberately falsifying results - i.e. scientific fraud.
   
• Bias - prior confidence in the hypothesis being true/false can affect accuracy of observation and interpretation of results.
   
• Data interpretation - research findings are limited by human ability to interpret the results. Wrong interpretations can lead to wrong conclusions e.g. thalidomide was used to treat morning sickness in human pregnancy in 1950s. It was safely tested on many animals and then wrongly interpreted as safe for humans. However, the drug was not tested on embryo in womb. This caused limb deformities in babies. The drug was later withdrawn in 1961.
   
• Is limited to the present - what is true now may not have been true in the past or in the future e.g. penicillin used to be effective against many bacteria but new strains have evolved that are resistant to penicillin.  As changes occur, scientific theories may require updating or revision.
   
• Ethical and legal responsibilities - Ethics refers to whether issues are right or wrong e.g. use of captive animals in experiments, origin of life, whether or not evolution took place, the way in which evolution may have taken place, contraception, abortion, assisted fertilisation, GMOs, cloning animals, freezing human sperm and embryos, the use of stem cells from embryos to form new tissues/organs, organ transplants e.g. from animals to humans.
   
• Accidental discoveries have contributed significantly to the development of scientific thinking - e.g. the discovery of antibiotic penicillin by Alexander Fleming in 1928. Fleming carelessly left a dish of bacteria uncovered and it became contaminated by a fungus. He noticed that the bacteria were killed in areas around the fungus. The fungus produced penicillin which killed the bacteria.