Déjà vu, the perceived memory of an event happening in the present moment, is one of the most peculiar human experiences there is. It can make us feel as if we have lived our lives before, exactly as they are now - echoing Nietzsche's eternal return perhaps. Here, philosopher Sam Woolfe, argues déjà vu is the merging of the virtual and actual worlds. The world of memory, imagination and so on, is the virtual. The actual is our shared reality. When the two meet, déjà vu occurs, and we have the strange feeling we have been here before.

In an intriguing essay titled ‘Memory of the Present and False Recognition’ (1908), the French philosopher Henri Bergson proposes that déjà vu is the result of memory and perception becoming intertwined in the present moment. This is based on his supposition that memory and perception – the past and the present – occur simultaneously. The British philosopher Keith Ansell-Pearson, who has translated Bergson’s work, writes:

Bergson’s claim is that at every moment of our lives we are presented with two aspects, even though the virtual aspect may be imperceptible owing to the very nature of the operations of perception. It is because the past does not simply follow the present but coexists with it that we can develop an explanation of paramnesia or the illusion of déjà-vu, in which there is a recollection of the present contemporaneous with the present itself. The illusion is generated from thinking that we are actually undergoing an experience we have already lived through when in fact what is taking place is the perception of the duplication we do not normally perceive, namely, of time into the two aspects of actual and virtual. There is a memory of the present in the actual moment itself. I cannot actually predict what is going to happen but I feel as if I can: what I foresee is that I am going to have known it – I experience a ‘recognition to come’. I gain insight into the formation of a memory of the present…

In Bergson’s own words:

As we witness an event or participate in a conversation, there suddenly arises the conviction that we have already seen what we are seeing, already heard what we are hearing, and already said what is being said … in sum, we are reliving down to the last detail an instant of our own past life. The illusion is sometimes so strong that in each moment, as long as this illusion lasts, we believe ourselves to be at the point of predicting what is about to happen: how could we not know already, if we feel that soon we will know that we knew it?

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Bergson was trying to dispel the illusion, which we do not commonly recognise as such, that a memory is formed after a perception has taken place.

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If we attend to the felt subjective quality of déjà vu, this does, indeed, ring true. When this experience lasts beyond a split second of uncanny familiarity, and a chain of thoughts is unfolding (usually for no longer than a matter of seconds), there is this sense that you know that the next detail will be familiar, and you are close to predicting it. This is like when you are trying to remember something that is on the tip of your tongue. During the déjà vu experience, you do not actually predict in the moment what the next detail will be, but when it does come, there is an immediate sense that you knew this would occur.