 Horgan and Tienson (2002) object to what they describe as “strong externalist theories” that maintain that causal connections are necessary for content. They argue, first, that mental life involves a lot of intentional content that is constituted by phenomenology alone. Perceptual states, such as seeing a red apple, are intentional. They are about apples. Believing that there are more than 10 Mersenne primes and hoping to discover a new Mersenne prime are also intentional states, in this case about Mersenne primes. But, all these intentional states have a phenomenology—something it is like to be in these states. There is something it is like to see a red apple, something different that it is like to believe there are more than 10 Mersenne primes, and something different still that it is like to hope to discover a new Mersenne prime. Horgan and Tienson propose that there can be phenomenological duplicates—two individuals with exactly the same phenomenology. Assume nothing about these duplicates other than that they are phenomenological duplicates. In such a situation, one can be neutral regarding how much of their phenomenological experience is veridical and how much illusory. So, one can be neutral on whether or not a duplicate sees a red apple or whether there really are more than 10 Mersenne primes. This suggests that there is a kind of intentionality—that shared by the duplicates—that is purely phenomenological. Second, Horgan and Tienson argue that phenomenology constitutively depends only on narrow factors. They observe that one’s experiences are often caused or triggered by events in the environment, but that these environmental causes are only parts of causal chains that lead to the phenomenology itself. They do not constitute that phenomenology. The states that constitute, or provide the supervenience base for, the phenomenology are not the elements of the causal chain leading back into the environment. If we combine the conclusions of these two arguments, we get Horgan and Tienson’s principal argument against any causal theory that would maintain that causal connections are necessary for content.