Newton as Philosopher is a book that defends Newton against a number of criticisms or misinterpretations. The main misconception was the “causal agnosticism” interpretation of early eighteenth-century Newtonians. Newton’s interpretation avoided all causal assertions in relation to gravity, which stated that bodies move in precise patterns that follow the inverse square law, although to major mechanist philosophers, such as Leibniz, the cause was left unclear. Janiak defends this by proposing that Newton describes gravity as existing and as a cause, acting at a distance. Liebnizian mechanists held that natural change could not occur via ‘action at a distance’, so the author delves into Newton’s gravity and argues that his concept of force was instead mass, not force. “Mass was alone, salient for gravity, although Newtonian gravity was yet accused of being an occult quality, and a universal quality of all bodies that was not God.” Janiak proposed that Newton downplayed gravity as a primary universal quality, and established the concept of mass, which was a unique idea compared to the previous, mechanical philosophy.
Newton did not reject Descartes, Leibniz or Huygens’ mechanical philosophy. Instead, he avoided speculating on the physical basis of gravity, simply because he believed that gravity acted directly between bodies across empty space, and defended a non-mechanical position of causation solely through empirical observation and mathematics. Stated simply, this helped Newton to transform natural philosophy into what is now modern physics.
Janiak claims, “the key to treating Newton as a philosopher lies in discovering how the mathematical treatment of force and motion forms part of the same enterprise as an investigation of seemingly separate metaphysical issues, such as God’s relation to the world.” He argues that Newton took a drastically empirical position on force and motion, but was portrayed as an anti-metaphysician at the time. The author explains...