The following two conclusions (symmetrical time dilation) validly follow from Einstein's 1905 postulates:

Conclusion 1: Moving clocks are slow and stationary ones are fast, as judged from the stationary system.

Conclusion 2: Stationary clocks are slow and moving ones are fast, as judged from the moving system.

Conclusions 1 and 2, in their combination, give no prediction concerning clocks. That is, even though conclusions 1 and 2 are logically correct (do follow from Einstein's postulates), their combination amounts to nonsense. We have reductio ad absurdum par excellence: the postulates entail absurdity which means that at least one of them is false. If Einstein had been honest, he would have identified the false postulate (constancy of the speed of light) and abandoned his theory immediately.

In 1905 Einstein effectively deleted both Conclusion 2 and the phrase "as judged from the stationary system" in Conclusion 1. So he "deduced" a conclusion equivalent to this statement (asymmetrical time dilation):

Moving clocks are slow and stationary ones are fast.

Needless to say, asymmetrical time dilation is non sequitur - it doesn't follow from Einstein's 1905 postulates. Yet Einsteinians have been teaching it very successfully for more than a century:

Albert Einstein 1911: "The clock runs slower if it is in uniform motion..." http://einsteinpapers.press.princeto...vol3-trans/368

Richard Feynman: "Now if all moving clocks run slower, if no way of measuring time gives anything but a slower rate, we shall just have to say, in a certain sense, that time itself appears to be slower in a space ship." http://www.feynmanlectures.caltech.edu/I_15.html

Brian Greene: "If you're moving relative to somebody else, time for you slows down." https://m.youtube.com/watch?v=QnmnLmwBmfE

Brian Cox (2:25): "Moving clocks run slowly" https://www.youtube.com/watch?v=-O8lBIcHre0

John Gribbin: "Einstein's special theory of relativity tells us how the Universe looks to an observer moving at a steady speed. Because the speed of light is the same for all such observers, moving clocks run slow..." http://www.newscientist.com/article/...lativity..html

Neil deGrasse Tyson: "We have ways of moving into the future. That is to have time tick more slowly for you than others, who you return to later on. We've known that since 1905, Einstein's special theory of relativity, which gives the precise prescription for how time would slow down for you if you are set into motion." http://abcnews.go.com/Entertainment/...ry?id=32191481

Jim Al-Khalili: "And, the faster you move and the longer you move at that speed, the slower your clock ticks, including your own internal biological clock, and so the slower you age - by tiny, tiny fractions of a second of course." http://www.jimal-khalili.com/blogs/2...m-with-the-app

Pentcho Valev