Yes but they are a monopoly. I believe in personal property but not government enforced monoplies especially on intangible ideas. Blockchain and open source will take over.
You're missing the point of patents.
In the absence of patents, someone who invents something novel must keep its design a closely guarded secret. Otherwise someone else (maybe quite a lot of others) will copy it and flood the market, making it impossible for the inventor to recoup his development costs.
By keeping the design secret, he's being just a monopolistic, but the rest of the world may never find out his secret.
With patents, the inventor is granted a legal monopoly for a fixed amount of time, in exchange for publishing his designs. So everybody knows the secrets, and once the time expires, everybody can benefit from that research.
I think it can be a meaningful discussion about whether the current duration (20 years from the first filing date) is too long, or if some thing (like software) should have shorter durations. I also believe that people who did not invent something and are not manufacturing it should not have the right to use patents to attack everybody else (e.g. patent trolls.)
But that having been said, I think it is very naive to assume, that the entire concept of patents should be eliminated. That would force inventors to go back to using trade secrets and would slow the rate of innovation in the marketplace.