There are various rationales for patent protection, below are some of the main ones:
Patents give incentives for economically effective Research and Development (R & D) by giving a monopoly on the patented invention. This encourages businesses to put millions of pounds into R & D which is ultimately of benefit society as a whole.
Patents encourage the disclosure of inventions to the public, without the protection of a patent many inventors would prefer to keep their inventions secret.
In some industries the cost of actually implementing an invention is higher than that of the R & D, if there was no way of protecting the invention then competitors would simply copy the invention and manufacture it for a fraction of the cost.
Due to the exclusive nature of patents competitors are encouraged to think up so called ‘work around’ ideas i.e. they know they cannot use the original invention due to the patent but how else could they come about with the same end result?. This brings about the creation of alternative technologies which but for the patent would not have been worked upon.