Final answer:
The statement is false; Plato's philosophical dualism was an original system and not a combination of Thales and Antisthenes' ideas. Thales and Antisthenes influenced the early philosophical landscape, but Plato developed his theory of forms, emphasizing a realm of unchanging truths beyond the material world.
Step-by-step explanation:
The statement that Plato combined the systems of Thales and Antisthenes into his own philosophical dualism is false. Plato was indeed greatly influenced by many thinkers, including the Pythagoreans, and most significantly by Socrates, from whom he derived the dialectic method of investigation. However, Plato's philosophical system, which contrasts the material world with the transcendental world of forms, was original and not a mere combination of Thales' and Antisthenes' ideas.
Thales, known for his belief that the primary substance of the universe was water, represents monism rather than dualism. Antisthenes, on the other hand, was a follower of Socrates and is noted for his ascetic ethics, but he did not heavily influence Plato's dualism. Thus, while Plato was a synthesizer of his predecessors' philosophical concepts, his dualism is not a direct combination of the philosophies of Thales and Antisthenes.