Conclusion
The aim of earth science is to provide descriptions and explanations and, if possible, predictions of phenomena on the earth and earth-like planets. Earth science can be viewed as a reductionist enterprise.
However, earth- scientific theories do not contain laws in the traditional sense of universal, exceptionless regularities. In contrast to physics and chemistry but analogously to biology, an important part of theories of earth science consists in descriptions of contingent states of nature. Yet, earth-scientific theories can be reduced locally because they can be exhaustively translated in physical and/or chemical terms. Earth science provides many cases of emergence, but recent attempts at reductionistic modeling suggest that many emergent phenomena may be explainable by the laws of physics in the near future.Earth-scientific explanations are strongly hampered by weak underdetermination. Underdetermination entails the impossibility of constructing complete causal explanations, but narrative explanations remain possible because they do not require an exhaustively detailed set of observations and initial conditions. Rather, references to time and length scales of interest provide implicit limits for the amount of details needed and refer to relevant background theories.
In general, theories or narratives in earth science provide explanations by integrating robust-process explanations and actual-sequence explanations, observations, and background theories. The narratives carry most of the explanatory power in both actual-sequence and robust-process explanations. The causal-explanation parts are, for example, tests whether the hypotheses do not conflict with physical laws or scenarios and coun- terfactuals derived from computer modeling. A conclusive test of the causal parts is, however, impossible due to the weak underdetermination problems. Two strategies are therefore followed: the method of multiple working hypotheses and inference to the best explanation. If the narratives survive tests against an increasing body of evidence, the hypotheses are more generally accepted by consensus as the best explanations. When earth scientists reach such a well grounded consensus on a historical narrative, the best explanation is that they possess knowledge of the past.