MMA ( Mixed martial arts )

really? for self defense its best to avoid disciplines that teach you to fight fare in a ring type setting. Boxing is for sport, Karve Manga is for fighting every thing else falls between the two

As far as I am concerned everything self defense labelled is a bit ... intangible.
How many success stories do we have proven? How many people that do [insert martial art here] have you seen defending themselves in a real situation? Everything else might be urban legend. [...]

The "no eyegouges" argument doesn't float in my books. Who says a trained competition martial artist wouldn't be able to poke someone or kick em in the nuts or poke them in the eyes ever?

Yeah: I have always found the 'self defence' versus 'sport' something of a false dichotomy when it comes to 'sports' like BJJ, muay thai and boxing. Like I say in my FAQ, taking part in competition (a defining characteristic of a sport) does not automatically mean a style is no good for self-defence. It merely means that its possible to use the techniques of that style in a regulated environment, which conversely can result in people who are capable of defending themselves using those same techniques, presuming its trained with 'aliveness' (in short, progressive resistance: if you're not familiar with the term, read this).

If any martial art claims to be applicable to self defence but does not include heavy contact sparring, then there is no way of knowing the validity of that claim. All that normally happens is that anecdotal evidence will be offered up, like "my mate is a bouncer and he uses aikido all the time" or "I used wing chun to defend myself in a street fight and it worked fine."

Styles like BJJ, muay thai etc can instead point to the numerous taped competitions to demonstrate that what they're teaching can be applied against a fully resisting opponent. Naturally this isn't the same as a street fight, as all sorts of other factors come into play (not just physical, but mental, verbal, chemical, environmental etc), but it is a high-pressure setting in which the technique can be tested.

This is not the case for styles which refuse to compete or spar, often using excuses like "our techniques are too deadly", which therefore effectively translates as "our techniques have never been tested. Also, as pascalo said, a 'sport' stylist can use an eye gouge just as easily as a 'self-defence' practitioner. Indeed, they can use it MORE effectively, because their training is likely to put them in a far more dominant position (e.g., a judo or BJJ guy will know how to obtain the mount and control you from there, meaning that they are much better placed to eye gouge etc).

This ability to prove the efficacy of a technique is especially true of MMA. Neither BJJ or muay thai cover the whole picture, as they focus on grappling and striking respectively: in a mixed martial arts fight, both can be used. MMA forms the closest thing currently available to a street fight, while still enabling both fighters to stay safe and keep on training.

The alternative is to go and start fights in bars, which would certainly prove whether or not your style was effective, but it would also likely lead either to serious injury or prison. On top of that, street fighting is a poor methodology for improving your efficacy, because it is too dangerous to do on a regular basis.

A BJJ or muay thai class, on the other hand, can be done regularly and safely. Because you're able to practice for long periods consistently, you'll get better, and you'll become more effective. The training methodology makes it effective, and it is this methodology that is missing from so many other martial arts, which in turns means they are far less useful.