How do we know Dodos existed? How do we know anything about them?
Subfossil remains show the dodo was about 1 metre (3 ft 3 in) tall and may have weighed 10.6–17.5 kg (23–39 lb) in the wild. The dodo's appearance in life is evidenced only by drawings, paintings, and written accounts from the 17th century. As these vary considerably, and only some of the illustrations are known to have been drawn from live specimens, its exact appearance in life remains unresolved, and little is known about its behaviour. Though the dodo has historically been considered fat and clumsy, it is now thought to have been well-adapted for its ecosystem. It has been depicted with brownish-grey plumage, yellow feet, a tuft of tail feathers, a grey, naked head, and a black, yellow, and green beak. It used gizzard stones to help digest its food, which is thought to have included fruits, and its main habitat is believed to have been the woods in the drier coastal areas of Mauritius. One account states its clutch consisted of a single egg. It is presumed that the dodo became flightless because of the ready availability of abundant food sources and a relative absence of predators on Mauritius.https://en.wikipedia.org/wiki/Dodo
Although we have some “subfossil evidence” of Dodos, because so little is known about them we are not sure of anything else about them besides the fact that they may have existed. In fact the disparity is so great that the claim can be made that whatever existing fossils we have may not be what was classicly known as a 'Dodo' because we have no knowledge or evidence that they were what would otherwise be known as a 'Dodo'.
The dodo was found interesting enough that living specimens were sent to Europe and the East. The number of transported dodos that reached their destinations alive is uncertain, and it is unknown how they relate to contemporary depictions and the few non-fossil remains in European museums. Based on a combination of contemporary accounts, paintings, and specimens, Julian Hume has inferred that at least eleven transported dodos reached their destinations alive.
Hamon L'Estrange's description of a dodo that he saw in London in 1638 is the only account that specifically mentions a live specimen in Europe. In 1626 Adriaen van de Venne drew a dodo that he claimed to have seen in Amsterdam, but he did not mention if it were alive, and his depiction is reminiscent of Savery's Edwards's Dodo. Two live specimens were seen by Peter Mundy in Surat, India, between 1628 and 1634, one of which may have been the individual painted by Ustad Mansur around 1625. In 1628, Emmanuel Altham visited Mauritius and sent a letter to his brother in England:
“Right wo and lovinge brother, we were ordered by ye said councell to go to an island called Mauritius, lying in 20d. of south latt., where we arrived ye 28th of May; this island having many goates, hogs and cowes upon it, and very strange fowles, called by ye portingalls Dodo, which for the rareness of the same, the like being not in ye world but here, I have sent you one by Mr. Perce, who did arrive with the ship William at this island ye 10th of June. [In the margin of the letter] Of Mr. Perce you shall receive a jarr of ginger for my sister, some beades for my cousins your daughters, and a bird called a Dodo, if it live.”
Whether the dodo survived the journey is unknown, and the letter was destroyed by fire in the 19th century. The earliest known picture of a dodo specimen in Europe is from a c. 1610 collection of paintings depicting animals in the royal menagerie of Emperor Rudolph II in Prague. This collection includes paintings of other Mauritian animals as well, including a red rail. The dodo, which may be a juvenile, seems to have been dried or embalmed, and had probably lived in the emperor's zoo for a while together with the other animals. That whole stuffed dodos were present in Europe indicates they had been brought alive and died there; it is unlikely that taxidermists were on board the visiting ships, and spirits were not yet used to preserve biological specimens. Most tropical specimens were preserved as dried heads and feet.
One dodo was reportedly sent as far as Nagasaki, Japan in 1647, but it was long unknown whether it arrived. Contemporary documents first published in 2014 proved the story, and showed that it had arrived alive. It was meant as a gift, and, despite its rarity, was considered of equal value to a white deer and a bezoar stone. It is the last recorded live dodo in captivity.https://en.wikipedia.org/wiki/Dodo
Up to eleven dodos apparently reached destinations abroad and were independantly studied. However, none of the accounts seems to agree, or show that it was an actual Dodo which arrived; i.e. none of the receivers had been experts on Dodos and were therefore unqualified to verify they had actually received a Dodo. Thus it is possible (and in fact plausable) that some other (similar) bird was transported, and that “Dodos” as a whole never existed.
This is supported by the fact that the extinction of dodos was not immediately noticed (above). Obviously even people at the time were unfamiliar with what a Dodo was, precisely, and thus did not notice when they “suddenly disappeared”.
Summary: It seems that the extinction of Dodos coincided with the close study of Dodos, and their “extinction” was mainly predicated on the fact that they were assumed to exist; yet as no one had any physical evidence or comporting account, it is more likely their “extinction” was merely the scientific discovery that they never existed.
The above is somewhat plausible, but extremely difficult to refute except by an expert or specialist. However, it is common for the layman to trust, or rely, on the tradition of oral knowledge that a) Dodos existed and b) this “fact” is confirmed by science. In reality we can raise considerable objection to both, and note that trust in modern science can at times be unfounded, and that what is really being trusted is a sort of modern scientific “oral law” which has been passed down from previous generations. Thus, if the existance of Dodos is plausable, the Kuzari Argument is plausable and in fact a stronger argument as the nation of Israel specifically set out to preserve their oral tradition.