2PartI Number and magnitude--On the nature of mathematical reasoning--Mathematical magnitude and experiment--PartII Space--Non-euclidean Geometries--Space and geometry--Experiment and geometry--PartIII Force--The classical mechanics--Relative and absolute motion--Energy and thermo-dynamics--Part IV Nature--Hypotheses in physics--The theories of modern physics--The calculus of probabilities--Optics and electricity--Electro-dynamics

1. Science -- Philosophy
2. Mathematics -- Philosophy
3. Probabilities