Let $P = (\Omega, \mathcal{F}, \mathbb{P})$ be a D1159: Probability space such that

(i)	$E, F, G \in \mathcal{F}$ are each an D1716: Event in $P$
(ii)	$F, G$ is a D5143: Set partition of $\Omega$
(iii)	\begin{equation} \mathbb{P}(F), \mathbb{P}(G) > 0 \end{equation}

Then \begin{equation} \mathbb{P}(E) = \mathbb{P}(E \mid F) \mathbb{P}(F) + \mathbb{P}(E \mid G) \mathbb{P}(G) \end{equation}