It has been argued that the Duhem problem is renewed with computational models since model assumptions having a representational aim and computational assumptions cannot be tested in isolation. In particular, while the Verification and Validation methodology is supposed to prevent such holism, Winsberg (Philos Compass 4:835–845, 2009; Science in the age of computer simulation, University of Chicago Press, Chicago, 2010) argues that verification and validation cannot be separated in practice. Morrison (Reconstructing reality: models, mathematics, and simulations, Oxford University Press, Oxford, 2015) replies that Winsberg overstates the entanglement between the steps. The paper aims at arbitrating these two positions, by stressing their respective validity in relation to domains of application. It importantly argues for an increasing use of formal methods in verification, that makes disentanglement possible.