Final answer:
Philosophical realists liken perception to a mirror, reflecting the external world, while idealists liken it to a dream or an illusion, emphasizing the mind's role in shaping reality. Realism focuses on direct knowledge through senses despite the possibility of being deceived by illusions, whereas idealism rejects material existence in favor of a reality composed of mental constructs or spiritual essence.
Step-by-step explanation:
Philosophical realists believe perception is like a mirror, while philosophical idealists believe perception is more like a dream or illusion. Realists argue that there is a world outside of our perception and we can gain knowledge of this world directly through our senses. Philosophical realists contend that our sensory experiences reflect reality as it is. However, even in the realm of direct realism, there is an acknowledgment that this reflection isn't perfect due to the potential for illusions and hallucinations, which may at times misrepresent reality.
On the other hand, idealists maintain that what we perceive is not the external world itself, but rather a construction within our minds. According to idealism, the material world does not exist independently of our perceptions. Instead, the ideas and concepts within our minds constitute reality. The physical universe is seen as secondary or even an illusion when compared to the realm of ideas and the mind.
The question about multiple realities brings up the debate over whether different individuals can have their own versions of reality or if there can be multiple entire realities existing simultaneously. Idealists would posit that since reality consists of ideas within minds, there are as many different realities as there are perceiving subjects.