  This appeal to explanation can naturally lead to (though it does not entail) another autonomy solution, the dual explanandum strategy. The Exclusion Problem presents a mental (functional) property M and its physical realizer P as competing to be causally relevant to the same effect, namely a bit of behavior. But M might not be threatened with exclusion if M and P are causally relevant to different properties of the effect. Return for a moment to the paperweight example from §3. The shape of the paperweight is relevant, not to the impression simpliciter, but to the impression’s shape. In general, a causally relevant property is relevant to some particular property of the effect (Horgan 1989). Perhaps, then, M and P do not causally compete because they are parts of separate, autonomous causal lines to different properties of the effect.