Justification by Imagination
Magdalena Balcerak Jackson
University of Cologne

The goal of this paper is to elucidate the epistemic role of imagination by reflecting on the similarities and differences between imagination, perception and memory. I will argue that imaginings have evidential value just as perceptions and memories do, but that they provide us with evidence of a different kind: with a priori justification for beliefs about the nature and structure of our perceptual experience.

I will focus on conscious mental states that represent objects and their visually accessible properties to us in a phenomenally salient way, whether or not there are objects with these properties in our actual environment. Let us call these mental states visual-type experiences, or V-experiences. V-experiences form a phenomenal kind in virtue of representing visual properties or appearance properties, but they come in three phenomenally distinctive flavors: perceptual experiences (perceptions, hallucinations and illusions), memory experiences (veridical and non-veridical recollections), and imaginings (visualizations).

The phenomenal differences between perceptions, memories and imaginings correspond to epistemic differences. On a traditional picture, perceptual experiences provide us with evidence about the visual properties of the world around us right now, memory experiences provide us with evidence about the visual properties of the world around us at an earlier time, and imaginings do not provide us with any evidence whatsoever. This is because what we imagine is independent of what is out there, and not causally dependent on an external stimulus. What we perceive is up to the world, what we imagine is up to us.

I will show that this traditional picture is mistaken. In a first step, I will distinguish two kinds of information that we get from perceptual experiences: empirical evidence and phenomenal evidence. Perceptual experiences tell us about the character of the external world. They help us to decide which of all the possible worlds is the actual world. And, perceptual experiences tell us about how things phenomenally seem to the subject of experience independently of whether the world is the way it seems to be. In a second step, I will then draw the consequences for the justificatory role of imagination. While imaginings do not provide empirical evidence, they do provide phenomenal evidence.

However, as I will argue it is wrong to assume that the evidential value of imagination is limited to justifying beliefs about the phenomenal properties of the current mental state. The fact that imagination is up to us, and that imagining is something we actively do rather than something that happens to us, has two kinds of consequences: It means that imaginings do not provide us with empirical evidence. But it also means that we can exploit our ability to create freely varied imaginings in order to systematically enquire into the phenomenal nature of our V-experiences. I will describe how we can come to be justified in believing general claims about the nature of V-experiences on the basis of a systematic use of imagination, and explain why this justification deserves to be called a priori.