Although there is an ongoing controversy in philosophy of science about so called ceteris
paribus laws that is, roughly, about laws with exceptionsóa fundamental question
about those laws has been neglected (ß2). This is due to the fact that this question
becomes apparent only if two different readings of ceteris paribus clauses in laws have
been separated.
The first reading of ceteris paribus clauses, which I will call the epistemic reading,
covers applications of laws: predictions, for example, might go wrong because we do
not know all the relevant factors which are causally effective in relevant situation. The
second reading, which I will call the metaphysical reading, is concerned with the laws
themselves and their possible exceptions (ß3). It is this latter readingóand the funda-
mental question associated with itówhich has been neglected due to the confusion of
the two readings (ß4): if we leave epistemic issues aside is there at all conceptual space
left for a notion of laws of nature which allows the laws themselves to have exceptions?
I call a law with exceptions in this sense, if such there is, a real ceteris paribus law.
To tackle this question, I distinguish grounded laws from non-grounded laws (ß5). A
grounded law is, roughly, a law about structured entities where the properties of the
parts of that structure figure themselves in laws of nature (ß6). I will claim that, since
the substructure of such an entity can be damaged, grounded laws themselves can face
exceptions. Hence, they are candidates to be real (metaphysical) ceteris paribus laws in
the sense of my central question. I will discuss grounded laws and their exceptions in
detail (ß7, ß8, ß9).
For reasons of space, the further question whether we can even have a notion of fun-
damental (non-grounded) laws that allows for exceptions cannot be discussed here. I
will, however, give a positive answer and also outline how I have argued for that claim
elsewhere (ß10)
