There is no greater impediment to the advancement of knowledge than the ambiguity of words.
Essays on the Intellectual Powers of Man, Essay 1, "Explication of Words" (1785).

Direct Realism (Naïve realism) Reid's philosophy was instigated by the works of David Hume, who in turn was motivated by Berkely.

David Berkley had in turn been motivated by John Locke.

I'll end the chain here, before I have to refer you back to Thales of Greece!

John Locke had argued that man could be understood as a machine. All that we really knew was matter and motion.

The problem that theists had with this is simple - if all there is, is matter and motion, then god would have to be a material object in time - in other words, the christian god couldn't exist!

Berkely replied by stating that first, man could never know matter directly. Second, that the existence of matter was something only to be found within our minds - things existed because we observed them. Furthermore, since man could not be everywhere, at all times, to observe everything, there had to be an omnipresent observer with a god's eye view of the universe to sustain reality.

Basically, some say that Berkley "destroyed" matter in order to save god. In reality, he never said that matter didn't exist so much as he said that we could be more certain of ideas than of matter - so, ipso facto, god is saved.

But things didn't end here.

David Hume came along, and tit for tat, pointed out that we can not be so certain of the mind either! The mind is, after all, only a name we give to ideas and sensations - in other words, there isn't really a "mind" in the first place, but the awareness of things and ideas.

Now, philosophy had basically said that there was no mind, but, as there was no matter either, I guess it didn't really... matter.

Except, that god was in trouble again.

So along comes Thomas Reid, the Scottish philosopher.

Reid went against Hume. He believed that sensations were reflected correctly and immediately. It was common sense that matter was reality. Reid used a legalistic argument to support this contention: He said that since many were incapable of possessing the intellect to realize the world in a philosophical manner, that the proof of matter had to be simple - it just was a bare fact of the world. This manner of claiming that a disputed fact can be simply accepted as a reality is known as Fideism. Reid went on to call theories that denied the reality of matter as mere "metaphysical lunacy". Many would probably agree with him and be happy to hear of the existence of a philosopher/theologian who thought this way.

The only problem is that nothing in modern science backs up this contention. We cannot assume that our sensations are reflected correctly. Reid was wrong and Hume was right, and that is that, in a fideistic nutshell. The fault that Reid comitted was the same mistake Descartes made - simply being "real sure" of something cannot verify its validity!

Reid on other Issues

Thomas Reid's Fundamental "Animal Action" Principles

Reid put forth the notion that certain cognitive abilities were simply instincts that all living things with advanced brains shared. Some of these instincts were:

"A Desire for Knowledge"

Knowledge was desired because it provided meaning for actions and events that occured to us. It was much easier to deal with a painful event if it had some meaning. Next, knowledge was useful in that it could help us both predict and control future events -it was a hedge against the anxiety that uncertainy caused. Knowledge could provide primary control, which allowed us to influence and affect the environment, and it granted us emotional secondary power, in that it allowed us to interpret events.

"A Need For Self Esteem"

All beings required a feeling of self efficacy for mental health. Without it, we could not attempt to act in the environment.

I concur with Reid's points here. In fact, I find them a useful precursor to modern psychology. In psychology, clients often come seeking meaning for events in their lives, and for a manner of increasing self esteem. For Reid to stress that these were necessary and instinctual to man makes him a forerunner to Maslow and his heirarchy of needs.