Why was Prof. Slughorn in Slytherin?

Question

It seems to me that Horace Slughorn would have belonged to Ravenclaw if anything.

He wasn't terribly ambitious himself (Slug club was about his vanity, not ambition).

He wasn't really evil (I mean, the man's main - if not only - vices are love of his creature comforts and being somewhat more cowardly than average Gryffindor).

He wasn't even anti-Muggle/mudblood, as evidenced by his likings of both Lily Evans and Hermione.

He was also clearly intelligent (otherwise he wouldn't have been a Potions teacher TWICE).

Why in the world did the Sorting hat put him in Slytherin?

Answer 1

First off, Slytherin isn't evil. The answer I linked does a more than sufficient job of debunking that.

Similarly, that same answer shows that the "pureblood" stance is not part of Slytherin, as "nowadays you’ll find plenty of people in Slytherin house who have at least one Muggle parent."

There's nothing that says intelligence is the sole domain of Ravenclaw. There are quite a few examples of highly intelligent members of other houses, the most obvious being Hermione (Gryffindor), Dumbledore (Gryffindor), and ... Snape (Slytherin!).

Regarding ambition... Slughorn's "Slug Club" really was a form of ambition. While vanity was certainly a part of it, the club was Slughorn's "cash cow" (or Wizarding equivalent). He selected people based upon their influence rather than fame. Luna Lovegood, for example, was the daughter of the publisher of a very well known newspaper, the Quibbler. However, that wasn't sufficient to interest Slughorn, as there is no evidence that Luna was ever invited to join the Slug Club.

Rather, he choose people who could either directly provide favors, or create opportunities for him. This is precisely the type of ambition that Slytherin House was known for.

This wiki entry summarizes Slughorn's benefits from his efforts fairly well:

When helping others become famous, which, if successful, gained him influence and/or benefits from them, such as being able to recommend the next junior member of the Goblin Liaison Office, free Quidditch tickets or a box of his favourite crystallised pineapple. Horace preferring to be a "back-seat driver", obtaining things he desires by using his contacts makes his life comfortable cosy.

Answer 2

We already know from Harry's choice of Gryffindor that the Sorting Hat considers the students preferences when it sorts them. Also when Hermione was sorted, she chose Gryffindor over Ravenclaw. Slughorn wanted power through connections more than anything. He wanted prestige and reputation. Slytherin, in his mind, would put him close to people that were going places, so to speak. He wouldn't choose Ravenclaw; Slughorn wasn't primarily interested in knowledge, but rather what knowledge would get him: power. He wasn't interested in courage or valor, so Gryffindor is unlikely. He would probably pick Hufflepuff least of all.

Slughorn was in Slytherin because Slughorn wanted to be.

Answer 3

I think that Slughorn was in Slytherin because He CHOSE to be in that house. After all, Slytherin is for not only the evil and the pureblood, but also for children who have Muggle parents but chose that house because they liked it. Example: Severus Snape wasn't pureblood. He chose the house because he wanted to be in it.

Answer 4

Albus Dumbledore described Slughorn as follows in Half-Blood Prince:

"Horace likes his comfort. He also likes the company of the famous, the successful, and the powerful. He enjoys the feeling that he influences these people. He has never wanted to occupy the throne himself. He prefers the back-seat; there is more room to spread out."

Quite simply, he is ambitious, but it's a different kind of ambition. He prefers exercising influence over people who wield power to actually wielding it himself. At one point, he even gave Harry an extensive description of various influential people he's friends with (major sports figures, Daily Prophet staff, etc.).

In fact, one of the main reasons he went back to Hogwarts in the first place is that he wanted to "collect" Harry. Dumbledore brought Harry to his meeting with Slughorn knowing full well that he'd want to do that in order to make it easier to convince Slughorn to come back.