Three resources have been developed over the ages to deal with agency.
The first one is to attribute to them naturality, and to link them wi
th nature. The second one is to grant them sociality, and to tie them
to the social fabric. The third one is to consider them as a semiotic
construction, and to relate agency with building of meaning. The origi
nality of science studies comes from the impossibility of clearly diff
erentiating between these three resources. Microbes, neutrinos of DNA
are at the same time natural, social and discourse. They are real, hum
an and semiotic entities in the same breath. The article explores the
consequences of this peculiar situation which has not been underlined
before science studies forced us to retie the links between these thre
e resources. The actor-network theory as developed by Gallon and his c
olleagues is an attempt to invent a vocabulary to deal with this new s
ituation. The article reviews those difficulties and Fries to overcome
them by showing how they may be used to account for the construction
of entities, that is for the attribution of nature, society and meanin
g.