𝙄𝘽 𝙏𝙊𝙆: 𝙒𝙝𝙮 𝙞𝙨 𝙀𝙖𝙧𝙩𝙝 𝙖 𝙥𝙡𝙖𝙣𝙚𝙩 𝙞𝙛 𝙋𝙡𝙪𝙩𝙤 𝙞𝙨𝙣’𝙩?

It is surprising what you discover when undertaking research for the Theory of Knowledge (TOK) component of the International Baccalaureate. TOK analyses the processes by which mankind develops knowledge.

𝙏𝙝𝙚 𝙨𝙩𝙤𝙧𝙮 𝙤𝙛 𝙋𝙡𝙪𝙩𝙤 Pluto’s chequered history as a “planet” illustrates some of the pitfalls of creating knowledge. Percival Lowell’s calculations led him to believe that there was a ninth planet beyond Neptune responsible for its orbital irregularities, prompting him to begin a search in 1906. Consequently, when a distant icy orbiting rock was discovered in 1930, after Lowell’s death, by a telescope at Arizona’s Flagstaff Observatory that Lowell had built, it seemed a triumph of rational, logical thinking - and not confirmation bias.

𝙎𝙪𝙧𝙚𝙡𝙮, 𝙋𝙡𝙪𝙩𝙤 𝙢𝙪𝙨𝙩 𝙗𝙚 𝙖 𝙥𝙡𝙖𝙣𝙚𝙩 Until late in the 20th century, Pluto’s status as a planet seemed a perfect example of logic, of deductive thinking: “Pluto orbits the sun, eight planets closer to the sun follow a similar pattern, therefore Pluto is a planet.” Indeed, it was also an example of inductive thinking too, working from the known to the unknown: “Those eight other orbiting bodies are planets, therefore Pluto is a planet too. However, as Dostoevsky had cautioned, “Man has such a predilection for systems and abstract deductions that he is ready to distort the truth intentionally.” 𝙏𝙝𝙚 𝙛𝙖𝙘𝙩𝙨 𝙘𝙝𝙖𝙣𝙜𝙚 In science facts are observations, perceived as regular and reliable. When the spacecraft Voyager passed Pluto in 1989 it became apparent that Pluto was nowhere near as large as initially thought. Then throughout the 1990s and beyond scientists discovered the Kuiper Belt of Objects. As one researcher later stated if Pluto, in the Kuiper Belt, was a planet then within a decade we might have around 110 planets. Suddenly, convenience and language were forming knowledge rather than reason. Remember that Niels Bohr had criticised Albert Einstein with the words, “You are not thinking. You are merely being logical.”

𝘾𝙤𝙣𝙛𝙪𝙨𝙞𝙣𝙜 𝙩𝙝𝙚 𝙞𝙨𝙨𝙪𝙚 The discovery of Pluto’s larger neighbour Eris, appropriately named after the Greek Goddess of strife and discord, further weakened Pluto’s cause.

𝙇𝙚𝙩 𝙪𝙨 𝙩𝙪𝙧𝙣 𝙩𝙤 𝙙𝙚𝙢𝙤𝙘𝙧𝙖𝙘𝙮 ... At the International Astronomical Union meeting of 2006 it was democracy in action which decided the issue. Delegates voted that Pluto should not be considered a planet because it did not meet the criteria of sweeping objects from its neighbourhood. Pluto was reclassified as a dwarf planet.

𝙎𝙤, 𝙞𝙨 𝙀𝙖𝙧𝙩𝙝 𝙖 𝙥𝙡𝙖𝙣𝙚𝙩? As Earth has around 12,000 asteroids in its neighbourhood, then it also fails the IAU’s criterion as applied to Pluto.

𝘾𝙤𝙪𝙡𝙙 𝙡𝙖𝙣𝙜𝙪𝙖𝙜𝙚 𝙙𝙚𝙛𝙞𝙣𝙚 𝙩𝙝𝙚 𝙠𝙣𝙤𝙬𝙡𝙚𝙙𝙜𝙚? A 2017 proposal suggested that a planet should be “a round object in space that's smaller than a star." Though on this vague criterion the Earth’s moon would be elevated to planet status. So far, it seems that our ways of knowing have failed to help, principally reason, frequently cited as the king of ways of knowing, has been of little help. Planetary scientist Alan Stern of NASA summed up the impasse, “My conclusion is that the IAU definition is not only unworkable and unteachable, but so scientifically flawed and internally contradictory that it cannot be strongly defended against claims of scientific sloppiness, "ir-rigor," and cogent classification.”