Where does vat collide?

In epistemology the brain-in-a-vat is a sceptical thought experiment: imagine a brain kept alive in a vat of nutrients and fed electrical signals that perfectly simulate ordinary experience, so that from the inside it could not tell the difference from real embodied life. Putnam's Reason, Truth and History uses the scenario to probe whether such a brain's words could even refer to real things, arguing on semantic grounds that the hypothesis is self-refuting. Here 'vat' is merely the container housing the brain; the construct is a challenge to knowledge of the external world, with nothing to do with dye chemistry or taxation.[1]

Unit

Whether beliefs formed from simulated input could count as knowledge

Recovery means

Not applicable

Measured by

Examined by argument, over whether the scenario is coherent and whether its terms can refer

In public finance VAT (value-added tax) is a broad consumption tax collected in stages along the production chain: each business charges tax on its sales but credits the tax it paid on inputs, so the net burden falls on the value it adds and ultimately on the final consumer. Ebrill and colleagues' The Modern VAT analyses how this credit-invoice mechanism makes the tax largely self-enforcing and why it spread worldwide. The shared string 'vat' is an acronym here, an entirely different referent from a dyer's vessel or a philosopher's thought experiment.[2]

Unit

Revenue raised on the value added at each stage of production

Recovery means

Not applicable

Measured by

Tracked by the standard rate, the credit-invoice chain, and collected revenue as a share of consumption