Cats can seem like very fickle creatures. One minute they are cuddly, rubbing you, and love being pet. The next minute, they have scratched you and you are now bleeding! Why would a cat do such a thing? Well, scratching is actually a natural instinct for a cat.
Even if you declaw your cat, they will continue to 'scratch' although they may not be destroying quite as much. However, when a cat is decalwed, they often resort to biting instead, which is not much better of a behavior. It is possible to train a cat to stop scratching, so, ultimately, declawing is not a good solution. In order to train a cat to stop scratching, you must first know why they scratch.
One of the many reasons why cats scratch is to leave behind a scent, marking the object as theirs. They have pheremone glands in their paws which release a scent when they scratch something, leaving the scent on the object or person. Scratching also helps them to relieve stress. It is also a great stretch for them. Cats who have been declawed often have trouble stretching which can cause stress on their joints.
One method to get cats to stop scratching is to provide them with an alternative thing to scratch which is made irresistable to them. This way they are still able to scratch, but are not harming anything or anyone.
Start out by purchasing a high quality scratching post. The best ones are made from sisal, wood, or carpeting. Do not buy a cheap one made from cardboard, this will not last long enought o be effective. Place it in an area where the cat spends a lot of time. You may be tempted to hide it, but it will be most effective if it is out in the open.
Make sure you purchase enough cat posts for all of your cats. You should follow the same rule as with litter boxes- one for each cat, plus one extra. Now, make them very enticing. Rub catnip on the cat posts to draw the cats in. Try to feed the cats and give them treats near the posts as well.
In the meantime, make the other places the cat likes to scratch less pleasant for the cat. A great way to do this is to put double sided tape where he likes to scratch. This doesn't harm the cat, but cats do not like how tape feels on their paws. Another option would be to cover your furniture in plastic.
Just make sure to not punish them for any scratching, cats do not understand punishment. Cats do understand reward though, so make sure to give them treats for scratching on the new posts.