>i've heard this has always been a popular theory but after
>watching it i just don't see how.

Once the director's cut was released it was a 90% probability he was a replicant - and after The Final Cut it was more like 95%.

1)Deckard has a day-dream about a unicorn - a dream he tells no one about. At the end of the movie when he's getting Rachel to escape they find a piece of origami left by Gaff. It is a unicorn.

2)They changed the way Deckhard's eyes reflect light in The Final cut - giving him the same look as Rachel.

There are other points people go to such as 'How could Deckard survive the fight with Roy, how could he climb a building with broken fingers, why does Gaff say "You've done a man's job." to him after Roy dies.

So in this film I think it makes sense that Deckard is a replicant still - if two replicant can have a baby then Tyrell's/Walalce's dream can become true without depending on humans to reporduce.