Final answer:
The philosopher known for writing a treatise on toleration, advocating for religious freedom, and believing in absolute freedom of speech is Voltaire.
Step-by-step explanation:
The philosopher who wrote the treatise on toleration, tried to understand the laws of economics using Newton's laws of motion, was a strong advocate of religious tolerance and freedom, and believed in absolute freedom of speech was Voltaire. While John Locke is well-known for his influential ideas on natural rights, government by the consent of the governed, and social contract theory, and Adam Smith is the father of modern economics with his work 'The Wealth of Nations', it is Voltaire who fits the description provided in the question best. Isaac Newton, although an influential figure in the history of science, is primarily celebrated for his work in physics and mathematics, not for writing on the social topics mentioned.