'Shippers:
What about the kiss in the hallway?

NoRoMos:

1. Mulder was only trying to tell Scully how much he needs her, not how
much he loves her.

Mulder is a very intense person, and when he expresses his emotions he tends to be very impassioned about it. In this scene, Mulder is desperate to keep Scully with him. She's the best partner he's ever had, and he needs her support *as a partner* to continue with his search. His words - "You make me a whole person" - only mean that her skepticism balances his paranoia, thus making them a team. They are complementary, best friends, but they are not in love. The almost-kiss was a desperate attempt to convince her to stay.
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2. Mulder was deceiving himself

Well, we all know that Mulder's sex life is non-existent. He's also a very lonely person. Scully is an intelligent, beautiful, loyal woman and she's his partner and best friend. Mulder *wants* to love her because she's worthy of love and because he feels very close to her. He said what he said because he wanted to love her so much that he almost believed he *did* love her. Notice how he didn't actually say "I love you"?
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3. Mulder was stressed

Obviously, Mulder was under a lot of pressure there. He'd given up what he believed for years only to have it shoved in his face that maybe he'd been right the whole time. On top of that, he's about to lose his best friend. It's natural for him to reach out to his best friend for comfort. The fact that he reached out with a kiss, well, that's just because a kiss is a more intense way of communicating emotion. One step up from a hug, if you will.
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4. Mulder was being manipulative

I don't like this explanation because I like Mulder, but it is possible that Mulder said everything because he wanted to keep Scully working with him. Basically, he was pulling out everything he had that might make her stay, and didn't really mean what he said.

~ Arguments courtesy of Krychick

Visit Krychick's Page for more arguments against the whole shipper thingy.