Meisner, Adler, Strasberg: pioneers in the American theatre who each took the teachings of Konstantin Stanislavsky, expanded upon and extrapolated from them to create their own acting processes which became the training backbone for generations of actors across the world. These famous names were among the first wave of teachers to modernise the craft of acting as the movement toward naturalism in the advent of film and television swept across the theatrical landscape in the mid 20th century. Next generation contemporaries again who have taken their techniques and further evolved them include the likes of Eric Morris, Ivana Chubbuck, William H. Macy/David Mamet (Practical Aesthetics) and more.
There are many training schools specialising in particular techniques. Each touts their technique being 'the one', the most effective. The truth is, they are all members of the same family. They all stem back to the work of Stanislavsky to find their genesis. They relate to each other very closely in their core values. They generally all agree on the destination and the desired end result. What they differ on is the path/process via which to best get there.
Meisner technique emphasises focus on the other actor and utilises Stanislavky's magic "If" (or 'As If' in Meisner parlance) along with a range of other tools to arm the actor to live truthfully under imagined circumstances. Lee Strasbourg's approach, more commonly known as 'Method', has the same goal, living truthfully under imagined circumstances, only his process prefers Sense Memory and Emotion Memory as the launchpads to authenticity. Practical Aesthetics prefers a doing based process, a focus on action. Funny thing though, you know what Meisner technique calls the doing part of the craft? "Doings" (of course). And you know what Method calls them? "Actions". In other words they each have their own language for these concepts but it's an example of how the concepts are common across multiple techniques. Granted each concept will have a different level of emphasis in each process, but the fundamental moving parts are the same whichever process from this family you study.
There's plenty of rhetoric, (mainly perpetuated by teachers I have to say), about which is right and which is wrong. But let me blow your mind for a moment and tell you the truth, THEY ARE ALL RIGHT. Yes, they all work. All these famous techniques have produced some great actors. Each will work for some actors and not for others. It's different strokes for different folks. Most importantly, and this is the key point, they are not mutually exclusive. You don't have to learn and master just one of these processes. You can learn them all, understand how they work, how they are useful, how they relate to each other and how to integrate all of the tools into your toolbox.
Actions, Objectives, As Ifs, Substitutions, Personalisations, Element of Truth, Identity, Sense Memory, Emotion Memory, Imagination... the list of tools goes on and on and is far too long to print in full here.
An integrated approach provides options for the actor, multiple access points if you like, to learn to work truthfully, to work authentically, to give performances that are alive with real interaction and real emotion. An integrated training approach also promotes a broad and overarching understanding of the craft of acting and all of it's moving parts. The more clearly you understand your craft, the greater your chances of finding your own way to master it.
Don't get caught up in the hype or the sales pitch around one or other technique. Study them all. Find what works for you. Don't get caught up in inter-school politics or partisan beliefs. Our art form is the ultimate beneficiary of craft mastery. It is also the main casualty of arguments about which technique is right or wrong. We are all passionate lovers of this beautiful craft we call acting. Serve it well.