Liberalism and Deep Ecology are usually regarded as mutually exclusive. However, the “evolutionary” tradition of liberal thought, rooted in David Hume and Adam Smith, and including Michael Polanyi and F. A. Hayek, provides a foundation for their reconciliation. Linkage is through Hume and Smith's conception of sympathy, which today means empathy. For Hume, sympathy extends into the animal realm. Sympathy is essential for certain scientific work, and provides an foundation for both liberal and ecological ethics. Deep ecologists such as Arne Naess use the same concept. Linkage is first to biocentric ethics, and then, through examining natural beauty and, via Michael Polanyi's tacit knowledge, ecocentric ethics. The work of Hayek suggests how modern society might be harmonized with the requirements of nature. This deepens J. Baird Callicott's pioneering approach, uniting it with Lewis Hinchman's recent analysis. Liberalism's and Deep Ecology's foundations both benefit from their mutual integration.