Modernism takes the view that (a) science investigates facts, and only facts; (b) factual knowledge is exhausted by what can be ascertained on the basis of observations and experiments.
Economics & Philosophy have drawn close to each other by economists having started to ask questions that were once considered philosophical in the pejorative sense of non-scientific, and by philosophers having started to address their questions in ways that resembles science more closely than traditional philosophy.
Philosophers of science think about questions concerning theory assessment and scientific methodology professionally. More generally speaking, philosophers of science are interested in metaphysical and epistemological issues raised by the sciences. Metaphysical issues are those pertaining to the most fundamental building blocks of nature and society such as objects, properties, individuals, laws of nature, social norms, causality and modality.
Epistemological issues concern the ways in which scientists find out about these in experiments, measurements and observations.
Philosophers of economics are philosophers whose work focuses on the theoretical, methodological and ethical foundations of economics.
The main theoretical framework in economics is given by theories of rational choice. To examine the foundations of rational choice theory means to examine the axioms and principles that underlie these theories, to assess whether they are justifiable as axioms and principles of rational choice and adequate as descriptive accounts of actual choice. To examine the foundations of economic theory also means to examine how to interpret economic models and laws and ask about the metaphysical underpinnings of economics: are there laws of nature on economics? What role do causal relations play? Are there only individuals or also social wholes?