And for these putative artificially sentient agents there is the additional challenge that we might have no idea what kinds of consciousness they might be experiencing. Imagine a system subject to an entirely new form of suffering, for which we humans have no equivalent or conception, nor any instincts by which to recognise it. Imagine a system for which the distinction between positive and negative feelings does not even apply, for which there is no corresponding phenomenological dimension. The ethical challenge here is that we would not even know what the relevant ethical issues were.
