Moral and ethical agreements require sufficiently shared values, or at least some common ground. We might think of this in terms of a shared ‘form of life’, ‘lebensform’, as Wittgenstein describes it in his Philosophical Investigations. Yet it is not clear what will be sufficient, nor how to bridge gaps when disagreement occurs, for instance on whether it is ever right to lie. Ethical and moral theories offer some guidance, but there is no guide for which theory one ought to follow. Whether you favour eudaimonist (flourishing, well-being), deontological (duty), or utilitarian (consequentialist) principles, the selection of a philosophy says much about who you are (preferences, judgements, beliefs) and your context (social, political, cultural). More than this it can indicate certain psychological and personal dispositions, whether defined as brain states, mental states, or personalities. In this article I outline some arguments for why ethics might need a philosophy of mind, and why this poses problems for ethical and moral theory building.