Quantitative analysts or “Quants” are a source of competitive advantage for financial institutions. They occupy the relatively powerful but often misunderstood role of modeling, structuring, and pricing complex financial instruments in the capital markets. But Quants often function in a discipline free from ethical burdens. Models used to price complex instruments are usually beyond the mathematical understanding of financial sector participants who rely heavily on the integrity of the Quant who built them. Although there has been some attempt to cover (...) the ethics of mathematics applied to the capital markets, designing a set of rules to guide the ethical behavior of Quants cannot be made explicit and remains inexpressible. Because Quants generally experience a sense of detachment from moral obligation, there is a growing need to convert moral detachment into engagement. Our framework is indebted to key elements of Wittgenstein’s practical ethics philosophy and Rawls’ justice principle. The burden of balancing justice as fairness as defined by Rawls with the inability to explicitly articulate ethical rules as defined by Wittgenstein must fall to the Quant. We propose that the threshold delineating the barrier between ethical detachment and engagement can only be defined by the Quants themselves. It is their moral duty to disclose their level of ethical engagement when their models are put into practice. (shrink)