Woods missed the cut at the Quicken Loans National last month on his return from a three-month break due to a back injury, but McIlroy believes that the former world number one will always be a contender at Majors.
We have all witnessed what Tiger has been able to do over his career, whether that's come back from injury and win, come back from any sort of off-course stuff and win," the Northern Irishman told reporters ahead of the Scottish Open, which begins on Thursday.
"Is it foolish for people to write him off? I would say so. If he's playing and he's competing, he's got as good a chance as any. I wouldn't write him off completely. I still think he can do things that we have never seen from any other golfer.
"I read some of the comments from a couple weeks ago, he said that he felt great and he hit some good drives. So if he feels 100 per cent healthy and his doctors give him the go ahead, then why not."
Woods has not won a competition since last August's Bridgestone Invitational.