Objectivity and Honesty in Science: The case of Light Interference Phenomena

In his book _La Valeur de la Science _published in 1905, French scholar Henri Poincaré (1854-1912) claimed: ‘Scientists have to deserve the truth; this is the unique goal Science is worthy of’.1 And he completed: ‘In order to achieve this goal, the scientist must get rid of his emotions and preconceptions; he must attest an unconditional sincerity’.2 But scientists are human beings animated by their own psychology and their own feelings. Power, pre-eminence, pride, ambition, career, revenge, rancour, jealousy, hypocrisy, disappointment, scandalmongering, friendship, cupidity, this list being non exhaustive, blur their judgments. Furthermore, most of the time they belong to a group and they have to follow their mentor’s ideas not to be rejected. Therefore, the very significance of Science, its aim and its method are often biased by their lack of objectivity and by their lack of intellectual honesty.  History of Science reveals several such circumstances in which Science and human behaviours are intricately linked. This is illustrated with a case study: beginning of the nineteenth century, the question of propagation of light raised once again by light interference experiments. After a short recall of the scientific and historical background, an analysis of the correspondences between the principal characters allow to portray them quite accurately. This leads to an interpretation of the situation that the sole reading of their published papers cannot provide. And it demonstrates that paradoxically but also obviously, Science is not only built up with Science