2. If a saying or event is found in more than one of the Gospel sources then it is from Jesus. This like the “more than one witness” element in law. If it is found in Mark and in Q and in “M” (stuff only in Matthew) and “L” (stuff only in Luke) and in John and in Gospel of Thomas etc it is more likely to have been said or done by Jesus. The less sources, the less provable. (Jesus practiced table fellowship with sinners.)I want to question this. My reading of the Jesus Seminar publications is that they in fact privilege only two alleged sources, Q and the Gospel of Thomas. A given feature can occur in Mark, Q, M and L and still not be red; indeed it will often not be pink. A good example of this is all apocalyptic Son of Man material, which is witnessed in all of those strands, Mark, Q, M and L, but which is never given a red/pink colouring by the Jesus Seminar. For material to get through their filter, it needs ideally to witnessed by Q1 (the earliest layer of Q) and the Gospel of Thomas. A good example is Q 6.20 // Thomas 54, "Blessed are the poor".
In practice, the criterion of multiple attestation is not especially important for the Jesus Seminar. The Parable of the Good Samaritan, for example, is red, in spite of the fact that it is only attested in one, late Gospel source (L).