Blockchain is a technology that makes use of a set cryptographic primitives that allow it to store information by consensus of the nodes without using a trusted central party. Blockchain mechanisms also make the stored information unalterable, and allow it to be verified in a quick way. This technology allows us to relate intangibles like truth, consensus and security. This paper presents the development of a polygraph application that can work in social networks using the users of the social network previously registered in the application as the nodes of a blockchain. Using the Nash equilibrium and techniques of Artificial intelligence a mechanism of consensus is created that allows the nodes to register information in the ledger. Truth and accuracy is one of today's greatest problems in social media platforms and as such we develop and present an architecture to work in facebook as the first application of our blockchain. The architecture is ethical by design, inspired by the moral formalism of Immanuel Kant as truth, and lying, were central concerns to his philosophy. The principles of his ethics can be implemented into blockchain technology so we establish a technology which upholds truth as a formal duty between people, by detecting falsehoods spread on social media. This ethical coding would in principle enable society to protect the rationality and dignity of its citizens. This is a small step towards the possibility of greater ethics en-coded in the practices of our digital world, whilst we do discuss and recognise the many technical and conceptual complexities – such as the nature of ‘truth’ and ‘ethics’ in itself, especially given Kant’s hard-lined philosophy. However, Kant's universality of thinking aligns well with the logic of computing; therefore ethical formalism appears to be a suitable first step in the exploration of philosophically inspired truth judgements in blockchain technology.