http://www.fourmilab.ch/etexts/einstein/specrel/www/
ON THE ELECTRODYNAMICS OF MOVING BODIES, by A. Einstein, June 30, 1905: "From this there ensues the following peculiar consequence. If at the points A and B of K there are stationary clocks which, viewed in the stationary system, are synchronous; and if the clock at A is moved with the velocity v along the line AB to B, then on its arrival at B the two clocks no longer synchronize, but the clock moved from A to B lags behind the other which has remained at B by tv^2/2c^2 (up to magnitudes of fourth and higher order), t being the time occupied in the journey from A to B."

According to special relativity, time dilation is MUTUAL. Here Einstein deals with two clocks in relative motion, and either of them is running slow as judged from the system of the other (so special relativity says). Accordingly, Einstein should have said:

1. The clock moved from A to B lags behind the clock at B, as judged from the clock at B's system.

2. The clock at B lags behind the clock moved from A to B, as judged from the moving clock's system.

Then Einstein should have concluded: Since the consequent (either clock lags behind the other) is absurd, the antecedent ("light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body") is false.

Pentcho Valev