Many philosophers of science think that most laws of nature (even those of fundamental
physics) are so called ceteris paribus laws, i.e., roughly speaking, laws with exceptions. Yet,
the ceteris paribus clause of these laws is problematic. Amongst the more infamous
difficulties is the danger that 'For all x: Fx ⊃ Gx, ceteris paribus' may state no more than a
tautology: 'For all x: Fx ⊃ Gx, unless not'.
One of the major attempts to avoid this problem (and others concerning ceteris
paribus laws) is to claim that the subject matter of laws are ascriptions of dispositions,
powers, capacities etc., and not the regular behaviour we find in nature. That we do not know
whether the cetera are paria in a specific situation does not matter to the dispositionalist
because the objects have the disposition regardless of the circumstances. The defence of the
latter claim is that dispositions can be instantiated without being manifested. Hence, the laws
that ascribe dispositions are strict and it looks as if they do not face the above mentioned
problems of ceteris paribus laws.
In this essay I attempt to show that these assumptions are wrong. I hope to illustrate
that not only does the ceteris paribus clause reoccur inside the dispositions, moreover, there
are laws—laws about non-fundamental entities with instable dispositions—which bear a
ceteris paribus clause that cannot be hidden in a disposition.