 For the sciences, application of methodological reductionism attempts explanation of entire systems in terms of their individual, constituent parts and their interactions.For example, the temperature of a gas is reduced to nothing beyond the average kinetic energy of its molecules in motion.Thomas Nagel speaks of 'psychophysical reductionism' (the attempted reduction of psychological phenomena to physics and chemistry), as do others and 'physico-chemical reductionism' (the attempted reduction of biology to physics and chemistry), again as do others.